This study was supported in part by a grant from the Deployed War-Fighter Protection (DWFP) Research Program, funded by the U.S. Department of Defense through the Armed Forces Pest Management Board (AFPMB). Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity employer.

1. Preliminary Setup and Alignment
<ol>
	<li>Prior to any testing, align the laser diffraction system components following the guidelines provided by the manufacturer to ensure proper system functionality and data quality.</li>
	<li>Follow proper safety precautions associated with the use of a Class IIIa laser avoiding direct eye exposure. Use proper Personal Protection Equipment if active ingredient chemical spray solutions are being used.</li>
</ol>
2. Ground Nozzle Droplet Sizing
<ol>
	<li>Prepare the &#34;active blank&#34; by adding 47.5 ml (reflects a mix rate of 0.25% v/v) of a 90% non-ionic surfactant to 19 L of water and mixing well using a stir rod in a cordless drill. Depending on the amount of testing to be done, larger volumes of active blank may be required.</li>
	<li>Pour the &#34;active blank&#34; spray mixture into the stainless steel pressure tanks, seal the tank and attach the input air pressure hose and the outgoing liquid hose feeding the spray nozzle.</li>
	<li>Confirm that the distance between the nozzle outlet and the measurement zone is 30.5 cm (12 in) using a tape measure. If it is, continue. If not, adjust by moving either the laser diffraction system or the nozzle.</li>
	<li>Install a standard 110 degree flat fan nozzle with a #05 orifice (noted as an XRC11005 nozzle) in the nozzle body attached to the traverse system. Adjust the nozzle orientation such that the long axis of the flat fan nozzle is oriented vertically in the tunnel but either rotating the nozzle within the mounting ring on the check valve or by changing the position of the check valve if the nozzle cannot be rotated to the correct position.</li>
	<li>Turn on the wind tunnel and set the airspeed to 6.7 m/sec by adjusting the fan speed and confirming the airspeed in the tunnel using a hot wire anemometer.</li>
	<li>Set the spray pressure to 276 kPa (40 psi) by adjusting the incoming air pressure using an inline pressure regulator. Confirm the pressure using an electronic pressure gauge installed immediately upstream of the spray nozzle.</li>
	<li>Position the nozzle at the top of the tunnel by activating and running the linear traverse to the top-most position prior to initiating the measurement process.</li>
	<li>Ensure that all experimental parameters (nozzle, pressure, solution, etc.) are properly recorded in the laser diffraction system data recording software by confirming that the parameters recorded on the User Parameters interface window match the testing conditions. 
	NOTE: This data parameter recording screen may vary by laser diffraction instrument.</li>
	<li>Initiate a reference measurement by selecting the Reference Measurement icon in the operating software to account for any dust or background particles.</li>
	<li>Initiate start of the measurement cycle. Depending on the laser diffraction system being used, a few seconds is typically required to focus the sensor prior to initiating the measurement process.</li>
	<li>Once the system indicates it is ready to start the measurement process, activate the spray by opening the liquid feed valve on the pressure tank. Once the spray is started, lower the nozzle through the laser beam using the traverse mechanism until the entire spray plume has passed through the measurement zone. Deactivate the spray by closing the liquid feed valve. 
	NOTE: On the laser diffraction system used by the authors, the actual measurement process does not initiate until the spray passing through the measurement zone achieves an optical concentration of 0.5%, and continues until an elapsed time of 10-12 sec has elapsed. These settings will vary by laser diffraction system and user settings.</li>
	<li>Repeat steps 2.7 - 2.11 for a minimum of 3 replicates. Determine if additional replicates are required by computing the mean and standard deviation for the DV0.1, DV0.5, and DV0.9 of the three replicates and ensuring that standard deviation is 10%, or less, of the mean. Perform additional replicates as needed to meet the criteria.</li>
	<li>Set the spray pressure to 414 kPa (60 psi) and repeat steps 2.7 - 2.12.</li>
	<li>Repeat steps 2.6 &#8211; 2.12 for each additional nozzle and pressure combination of interest.</li>
	<li>Export and save droplet size data using the method provided within the operating software.</li>
</ol>
3. Aerial Nozzle Droplet Sizing
<ol>
	<li>Prepare the &#34;active blank&#34; by adding 47.5 ml of a 90% non-ionic surfactant to 19 L of water and mixing well using a stir rod in a cordless drill. 
	NOTE: depending on the amount of testing to be done, larger volumes of active blank may be required.</li>
	<li>Pour the &#34;active blank&#34; spray mixture into the stainless steel pressure tanks, seal the tank and attach the input air pressure hose and the outgoing liquid hose feeding the spray nozzle.</li>
	<li>Confirm that the distance between the nozzle outlet and the measurement zone is 45.7 cm (18 in) using a tape measure. If it is, continue. If not, adjust by moving the laser diffraction system the required distance from the nozzle.</li>
	<li>Install a standard 20 degree flat fan nozzle with a #15 orifice (noted as a 2015 nozzle) in a check valve and nozzle body onto the boom traverse section at the wind tunnel outlet. Ensure that the nozzle is correctly positioned with the nozzle body oriented horizontally and parallel to the airstream.</li>
	<li>Turn on the wind tunnel blower and set the airspeed at the tunnel outlet to 53.6 m/sec (120 mph) and confirm speed using pitot tube attached to an airspeed indicator.</li>
	<li>Set the spray pressure to 207 kPa (30 psi) by adjusting the incoming air pressure using an inline pressure regulator.</li>
	<li>Position the nozzle at the top position of the traverse prior to initiating the measurement process.</li>
	<li>Ensure that all experimental parameters (nozzle, pressure, solution, etc.) are properly recorded in the laser diffraction system data recording software by confirming that the parameters recorded on the User Parameters interface window match the testing conditions. 
	NOTE: This data parameter recording screen may vary by laser diffraction instrument.</li>
	<li>Initiate a reference measurement by selecting the Reference Measurement icon in the operating software to account for any dust or background particles.</li>
	<li>Initiate start of the measurement cycle. Depending on the laser diffraction system being used, a few seconds is typically required to focus the sensor prior to initiating the measurement process.</li>
	<li>Once the system indicates it is ready to start the measurement process, activate the spray by opening the liquid feed valve on the pressure tank. Once the spray is started, lower the nozzle through the laser beam using the traverse mechanism until the entire spray plume has passed through the measurement zone. Deactivate the spray by closing the liquid feed valve. 
	NOTE: On the laser diffraction system used by the authors, the actual measurement process does not initiate until the spray passing through the measurement zone achieves an optical concentration of 0.5%, and continues until an elapsed time of 5-7 sec has elapsed. These settings will vary by laser diffraction system and user settings.</li>
	<li>Repeat steps 3.7 - 3.11 for a minimum of 3 replicates. Determine if additional replicates are required by computing the mean and standard deviation for the DV0.1, DV0.5, and DV0.9 of the three replicates and ensuring that standard deviation is 10%, or less, of the mean. Perform additional replicates as needed to meet the criteria.</li>
	<li>Repeat steps 3.4 &#8211; 3.12 for each additional nozzle, pressure, nozzle orientation and airspeed combination of interest.</li>
	<li>Export and save droplet size data using the method provided within the operating software.</li>
</ol>

<ol>
	<li>Bouse, L. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+nozzle+type+and+operation+on+spray+droplet+size.">Effect of nozzle type and operation on spray droplet size.</a> Trans. ASAE. 37 (5), 1389-1400 (1994).</li><li>Hewitt, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Droplet+size+and+agricultural+spraying,+Part+I:+Atomization,+spray+transport,+deposition,+drift+and+droplet+size+measurement+techniques.">Droplet size and agricultural spraying, Part I: Atomization, spray transport, deposition, drift and droplet size measurement techniques.</a> Atomization Spray. 7 (3), 235-244 (1997).</li><li>Black, D. L., McQuay, M. Q., Bonin, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser-based+techniques+for+particle-size+measurement:+A+review+of+sizing+methods+and+their+industrial+applications.">Laser-based techniques for particle-size measurement: A review of sizing methods and their industrial applications.</a> Prog. Energy Combust. Sci. 22 (3), 267-306 (1996).</li><li>SDTF (Spray Drift Task Force). <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+No+A95-010,+Miscellaneous+Nozzle+Study.">Study No A95-010, Miscellaneous Nozzle Study.</a> EPA MRID, No. 44310401. , (1997).</li><li>Dodge, L. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+performance+of+drop-sizing+instruments.">Comparison of performance of drop-sizing instruments.</a> Appl. Optics. 26 (7), 1328-1341 (1987).</li><li>Arnold, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comparative+study+of+drop+sizing+equipment+for+agricultural+fan-spray+atomizers.">A comparative study of drop sizing equipment for agricultural fan-spray atomizers.</a> Aeronaut. Sci. Tech. 12 (2), 431-445 (1990).</li><li>Teske, M. E., Thistle, H. W., Hewitt, A. J., Kirk, I. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conversion+of+droplet+size+distributions+from+PMS+optical+array+probe+to+Malvern+laser+diffraction.">Conversion of droplet size distributions from PMS optical array probe to Malvern laser diffraction.</a> Atomization Spray. 12 (1-3), 267-281 (2002).</li><li>Fritz, B. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+droplet+size+of+agricultural+spray+nozzles+-+Measurement+distance+and+airspeed+effects.">Measuring droplet size of agricultural spray nozzles - Measurement distance and airspeed effects.</a> Atomization Spray. 24 (9), 747-760 (2014).</li><li>ANSI. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> ASAE S572.1 Spray Nozzle Classification by Droplet Spectra. 4, 1-3 (2009).</li><li>Fritz, B. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+drop+size+data+from+ground+and+aerial+nozzles+at+three+testing+laboratories.">Comparison of drop size data from ground and aerial nozzles at three testing laboratories.</a> Atomization Spray. 24 (2), 181-192 (2014).</li><li>Fritz, B. K., Hoffmann, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Update+to+the+USDA-ARS+fixed-wing+spray+nozzle+models.">Update to the USDA-ARS fixed-wing spray nozzle models.</a> Trans ASABE. 58 (2), 281-295 (2015).</li><li>Sympatec Inc. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> HELOS Central Unit Operating Instructions. , (2002).</li><li>Elbanna, H., Rashed, M. I., Ghazi, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Droplets+from+liquid+sheets+in+an+airstream.">Droplets from liquid sheets in an airstream.</a> Trans ASAE. 27 (3), 677-679 (1984).</li><li>Box, G. E. P., Behnken, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Some+new+three-level+designs+for+the+study+of+quantitative+variables.">Some new three-level designs for the study of quantitative variables.</a> Technometrics. 2 (4), 455-475 (1960).</li><li>Myers, R. H., Montgomery, D. C., Anderson-Cook, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Response Surface Methodology: Process and Product Optimization Using Designed Experiments. , 704 (2009).</li><li>Fritz, B. K., Hoffmann, W. C., Anderson, J., Goss, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Response+surface+method+for+evaluation+of+the+performance+of+agricultural+application+spray+nozzles.">Response surface method for evaluation of the performance of agricultural application spray nozzles.</a> Pesticide Formulation and Delivery Systems: 35th Volume, ASTM STP1587. , 61-76 (2016).</li></ol>

The authors have nothing to disclose.

There are a number of critical steps that should be followed when applying this method. With both aerial and ground nozzle evaluations, the distance from the exit of the nozzle to the line of measurement should be verified prior to any measurement. Any variance in this distance can have a significant impact on the results. Similarly, the concurrent airspeed used in ground nozzle testing should be verified and adjusted to the 6.7 m/sec recommended. Differences in airspeed from that recommended will significantly influence the results due to sampling bias issues at lower airspeeds, and potentially increase secondary breakup at higher airspeeds. Also, proper alignment of the laser diffraction system components is critical in order to ensure the system is operating at the accuracy and precision specification certified by the manufacturer. Proper setup and alignment of the nozzles relative to the concurrent airflow is critical to ensuring quality data, as even slight misalignments of a few degrees in the nozzles positioning can result in significant impacts on the resulting droplet size data.
The methods presented can be applied to any spray nozzle configuration or spray solution for both ground and aerial system. With ground sprayers, changes in spray droplet size are typically a function of nozzle type and size, spray pressure and spray solution type. With aerial sprayer the additional role of changes in airspeed and the orientation of the nozzle to surrounding airstream are critical to the resulting droplet size. This method can be used to evaluate the combined effect of these factors on the final droplet size. However there are rare instances when some modifications to the recommended methods are required. Specifically, spray solutions or nozzles that require further distances from the nozzle for complete breakup of spray into discrete particles will require adjusting the distance between nozzle and measurement point. To date, the only nozzle/spray solution treatments that have required this sort of adjustment have been straight stream nozzles at all operational settings and narrow angle flat fan nozzles with spray additives that increase the solutions viscosity, when measured under aerial application testing conditions. The laser diffraction system will still return droplet size data in the event of incomplete breakup of the spray cloud, but the resulting data will typically be biased toward much larger droplet sizes as a result of spray ligaments being measured by the system. While these ligaments are not readily apparent to the naked eye, their presence will typically show up visually in the distribution plot as a secondary peak at the larger end of the droplet size scale (Figure 3). Though caution is advised in assuming that this secondary peak is the result of the presence of ligaments, as external vibrations or other interference with the laser diffraction system may cause a similar response. As a user&#39;s experience level increases, making the distinction between the two based on errors becomes easier. In the case where spray atomization is incomplete, we have found that extending the sampling distance to 1.8 m (for aerial spray nozzles) resolves the issue and returns quality data. This 1.8 m distance is in fact the standard distance at which our group evaluates all straight stream nozzles under aerial application conditions. When working with ground sprayer nozzles, there are a class of nozzle designs that use a twin, flat fan orifice outlet the may require modification to the nozzle mounting setup to insure the entire spray plume passes through the sampling area without fouling the laser diffraction system&#39;s lenses.
While this method is designed to minimize the sampling bias due to spatial biases associated with laser diffraction systems, it does not completely eliminate them, meaning that the droplet size values return cannot be taken as &#34;absolute&#34;. Laser diffraction does not provide a means to measure, and adjust, the resulting droplet size data for the non-homogeneous droplet velocities amongst the different droplet sizes in the composite spray cloud. This becomes critical when inter-laboratory data sets are compared, particularly with respect to ground spray nozzles. The method currently accepted to standardize the results and allow comparisons between laboratories uses a series of highly calibrated reference spray nozzles, whose droplet size data are used to establish a set of classification categories. Evaluation of these nozzles should be conducted as part of every droplet sizing evaluation. Further details on the nozzles and classification definitions can be found in the American Society of Agricultural and Biological Engineers (ASABE) &#34;Spray Nozzle Classification by Droplet Spectra&#34; International Standard (ASAE/ANSI, 2009).
As discussed in the Introduction, there are other droplet sizing systems besides laser diffraction. Where laser diffraction provides a composite measure of droplet size across the entire spray plume, these other methods focus in on a small area with the spray cloud, sampling only a small portion of the overall spray cloud. Obtaining a representative sample of the entire plume with these others methods requires a much more rigorous, and time consuming, multi-chordal traverse of the spray plume&#39;s cross section area, resulting in a large number of sub-samples that must be combined to generate a composite result. This requires significantly more time than using laser diffraction.
Once this method has been successfully integrated into a research program and the techniques mastered by the users, the next challenge is conducting well-structured experiments aimed at understanding the role each of the influence factors play with respect to the formation of droplet size. This is a bigger challenge than it seems given the seemingly endless combination of nozzle type, nozzle setup and operational factors, airspeed and nozzle position (aerial spraying) and real-world tank mixes used by the agricultural application industry. Even more of a challenge is finding a way the makes this information available to the applicators in a format that is easily useable. One option our group has used with great success is a class of experimental designs called response surfaces that allow for the development of droplet size prediction models based on a limited number of experimental treatments allowing for an extremely efficient evaluation of multiple spray nozzles and solutions14, 15. This structured design method has been used to develop a series of droplet size models for the most commonly used aerial11 and ground nozzles16 used by agricultural applicators.

When making any agrochemical spray application, the primary concerns are ensuring maximum biological efficacy while minimizing any off-target movement and associated adverse environmental impact or other non-target biological harm. One of the principal factors to consider when setting up any sprayer, prior to an application, is droplet size, which has long been recognized as one of the primary parameters influencing overall spray deposition, efficacy, and drift. While there are a number of other factors that potentially impact spray deposition and drift, droplet size is one of the easiest to change to fit the needs of a given application scenario. Droplet size from any agricultural spray nozzle is influenced by a number of factors including, but not limited to, nozzle type, nozzle orifice size, spray pressure and spray solution physical properties. With aerial applications, the additional influence of air shear resulting from the airspeed of the aircraft and the nozzle&#39;s orientation relative to that airshear, causes secondary breakup of the sprays leaving the nozzles1. With all of these factors, applicators are faced with the difficult task of making proper nozzle selection and operational setup decisions that insure that all pesticide products labels are met and that the resulting spray droplet size is such that on-target deposition and biological efficacy are maintained while minimizing off-target movement. The goal of this method is to provide clear, concise information on the droplet size resulting from the various combinations influencing factors to support an applicator&#39;s operational decisions.
While there are a number of instruments available for measuring droplet size from sprays, measurements from agrochemical spray nozzles are typically either laser diffraction, imagery, or phase doppler based2. The imagery and phase doppler based methods are single particle counter methods, meaning that smaller areas within the spray cloud are focused on, with individual particles being measured3. Whereas laser diffraction methods take an ensemble measurement, meaning the distribution of a group of particles is rapidly measured3. While these methods differ in principle, with proper setup and use, comparable results can be obtained4. Laser diffraction methods have been widely adopted by the agricultural application community due to the ease of use, ability to rapidly measurement high number density sprays and the large dynamic measurement range. As an ensemble measurement is made, a single traverse of a spray plume through the line of measurement is all that is required for a composite droplet size of the entire spray. This allows for efficient evaluations of droplet size from a large number of spray nozzles and operational parameter combinations. By comparison, the single particle counter methods necessarily focus on much smaller areas within a spray cloud in order to capture individual particles, meaning that multiple measurement locations must be evaluated and combined to return a composite result. This requires significantly more time, effort and spray solution to evaluate a single spray plume than laser diffraction based methods. The increased spray volume required can present a significant problem if actual pesticide products are being tested as a result of increased costs of the material used and the disposal costs. However, the single particle counter methods offer the advantage of providing a temporal sample, in that they measure the number of droplets per unit time passing through a sample volume, whereas laser diffraction provides a spatial sample as the measurement is proportional the number of droplets within a given volume5. Were all droplet velocities within a given spray the same, the methods would provide identical results. However, for most spray systems the droplet velocities are correlated to droplet size, resulting in a bias with spatial sampling methods6.
Overcoming this spatial bias from laser diffraction measurements through appropriate testing methodology is a critical part of evaluating spray droplet size from agricultural spray nozzles4. The spatial bias is reduced when testing nozzles in a concurrent airstream of 13 m/sec and with the measurement location located an appropriate distance from the nozzle, as the combination of these two parameters results in homogeneous droplet velocities throughout the spray cloud4. Further, the spatial bias is small (5% or less) for aerial nozzle testing due to the high concurrent airspeeds evaluated7,8. To determine the optimal test method to reduce the spatial bias with our current low and high speed wind tunnel facilities, the series of reference nozzles used to determine agricultural spray size classifications9 were evaluated for droplet size using both laser diffraction and imaging methods10. Sizing evaluations were conducted under multiple combinations of concurrent air velocity and measurement distance (distance from the nozzle exit to the point of measurement), representative of the operational range of the existing facilities. Laser diffraction measurements were compared to imagery results to determine the potential spatial bias and the optimal combination of measurement distance and concurrent airspeed was selected as the standard operational procedure. A measurement distance of 30.5 cm and a concurrent airspeed of 6.7 m/sec for evaluation of ground spray nozzles in the low speed wind tunnel reduced spatial bias to 5% or less10. Spatial biases of 3% or less were obtained for aerial nozzle evaluations in the high speed tunnel, for all airspeeds tested, with a measurement distance of 45.7 cm10. Using these standard methods, the authors were also able to demonstrate that lab to lab variability could be minimized, providing for consistent interlaboratory droplet size data11.
All droplet size testing demonstrated as part of this work was conducted at the USDA-ARS-Aerial Application Technology Research Unit&#39;s spray atomization research facility. A laser diffraction system was positioned downstream of the nozzle at the distances specified in the Protocol section. For ground nozzle testing, the laser diffraction system was configured, following the manufacturer&#39;s instructions, to have a dynamic size range of 18-3,500 &#181;m across 31 bins12. Likewise for the aerial nozzle testing the system was configured with a dynamic size range of 9 to 1,750 &#181;m, also across 31 bins12. Aerial based spray nozzle evaluations were conducted in high speed air to simulate aerial application conditions. Ground sprayer nozzles were tested in a larger wind tunnel section with a single concurrent airspeed to minimize the spatial bias from laser diffraction. Nozzles being tested were positioned upstream of the laser diffraction system at the distances given in the Protocol section. Nozzles were mounted on a linear traverse allowing for the spray plume to be traversed vertically through the measurement zone during a given measurement cycle. The Protocol for ground nozzle testing describes an experiment examining three typical nozzles at two spray pressures while the aerial nozzle testing describes an experiment examining two typical spray nozzles at two spray pressures and three airspeeds. Both testing scenarios use an &#34;active blank&#34; spray solution, rather than water only, to mimic the effects of real world spray solutions.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>90% Non-ionic surfactant</td>
			<td>Wilbur-Ellis</td>
			<td>R11</td>
			<td>R11 is the trade name of Wilbur-Ellis non-ionic surfactant.&#160;</td>
		</tr>
		<tr>
			<td>HELOS-VARIO/KR</td>
			<td>Sympatec GmbH System-Partikel-Technik</td>
			<td>HELOS-VARIO/KR</td>
			<td>This system is available with several different lens options that change the effective measurement size range.&#160;&#160;</td>
		</tr>
		<tr>
			<td>Wind Tunnel/Blower systems</td>
			<td>Custom built</td>
			<td>n/a</td>
			<td>Airspeed range of Low speed system is 0-7 m/s and high speed from 18-98 m/s</td>
		</tr>
		<tr>
			<td>Air Compressor</td>
			<td>n/a</td>
			<td>n/a</td>
			<td>There is no specific air compressor needed to feed the system.&#160; However, the larger the tank volume and the higher the working volumetric flow rating, the better it will keep up with the testing.</td>
		</tr>
		<tr>
			<td>2015 and 4015 Aerial Nozzles</td>
			<td>CP Products</td>
			<td>CP11TT and CP05 swivel with 2015 and 4015 tips</td>
			<td>These were the aerial nozzles detailed in the methods, however, any number of spray&#160; nozzles can be evaluated by this method.</td>
		</tr>
		<tr>
			<td>11005, AI11005 and TTI11005 Ground Nozzles</td>
			<td>Spraying Systems</td>
			<td>XR11005, AI11005 and TTI11005</td>
			<td>As with the aerial spray nozzles, these were the nozzles detailed in the Protocol, but this method is not limited to these nozzles.</td>
		</tr>
		<tr>
			<td>200 psi Stainless Steel pressure tank</td>
			<td>Alloy Products Corp.</td>
			<td>B501-0328-00-E-R</td>
			<td>There are a number of suppliers with similar pressure vessels that can be used.&#160; This suppliers had the highest pressure rated tanks on the market.</td>
		</tr>
		<tr>
			<td>Various plumbing and air fittings and hoses</td>
			<td>n/a</td>
			<td>n/a</td>
			<td>Liquid and air plumbing fittings and hoses as needed to plumb the entire system.</td>
		</tr>
		<tr>
			<td>200 psi Pressure regulator</td>
			<td>Coilhose Pneumatics</td>
			<td>8803GH</td>
			<td>Any pressure regulator will work, this one was size to meet the high pressure needs as well as the plumbing used.</td>
		</tr>
		<tr>
			<td>Pressure transducer</td>
			<td>Omega&#160;</td>
			<td>PX419-150GV</td>
			<td>This pressure transducer was selected to fit the higher pressure loads we use.&#160; There are other pressure ranges available from the manufacturer.</td>
		</tr>
		<tr>
			<td>Airspeed Indicator</td>
			<td>Aircraft Spruce</td>
			<td>Skysports dual dial airspeed indicator 30-250 mph.</td>
			<td>Any airspeed indicator can be used.&#160; This one was selected to fit the speed range of our high speed aerial nozzle testing tunnel.</td>
		</tr>
		<tr>
			<td>Hot Wire anemometer</td>
			<td>Extech</td>
			<td>407119</td>
			<td>There are also a variety of options for measureing the airspeed in the low speed wind tunnel used for testing ground nozzles.&#160;</td>
		</tr>
	</tbody>
</table>

measuring spray droplet size from agricultural nozzles using laser diffraction

When making an application of any crop protection material such as an herbicide or pesticide, the applicator uses a variety of skills and information to make an application so that the material reaches the target site (i.e., plant). Information critical in this process is the droplet size that a particular spray nozzle, spray pressure, and spray solution combination generates, as droplet size greatly influences product efficacy and how the spray moves through the environment. Researchers and product manufacturers commonly use laser diffraction equipment to measure the spray droplet size in laboratory wind tunnels. The work presented here describes methods used in making spray droplet size measurements with laser diffraction equipment for both ground and aerial application scenarios that can be used to ensure inter- and intra-laboratory precision while minimizing sampling bias associated with laser diffraction systems. Maintaining critical measurement distances and concurrent airflow throughout the testing process is key to this precision. Real time data quality analysis is also critical to preventing excess variation in the data or extraneous inclusion of erroneous data. Some limitations of this method include atypical spray nozzles, spray solutions or application conditions that result in spray streams that do not fully atomize within the measurement distances discussed. Successful adaption of this method can provide a highly efficient method for evaluation of the performance of agrochemical spray application nozzles under a variety of operational settings. Also discussed are potential experimental design considerations that can be included to enhance functionality of the data collected.

The resulting data from this method can be expressed in a variety of formats, depending on the user&#39;s preference and the operational capabilities of the laser diffraction system. Typically this data is presented as a plot of the volume weighted droplet size distribution (Figures 1 and 2) or as descriptive droplet size metrics (Tables 1 and 2). These results can then be used to examine the impact that changes in nozzle or operational parameters have on the resulting spray droplet size.
We examined two different aerial spray nozzles, both with the same orifice size but with different spray fan angles. With these two aerial nozzles, we also examined the effects of spray pressure and airspeed on droplet size. Examining the 2015 nozzle operated at a spray pressure of 207 kPa and comparing the volume weighted distributions resulting from the same nozzle being operated in 53.6 m/sec versus 71.5 m/sec airspeed, it is immediately obvious that the higher airspeeds results in a dramatic shift in the incremental and cumulative distributions toward smaller droplet diameters (Figures 1 and 2) which is the result of increased breakup of spray droplets at the higher airspeed. While the graphical representation of the results provide a very visual representation of the results, quantitative values derived from these distributions are more practical for larger data sets. Typical droplet size metrics used in agricultural spray research include the DV0.1, DV0.5 and DV0.9 values, which correspond to the droplet diameters such that 10, 50 and 90% (respectively) of the spray volume is contained in droplets of equal or lesser diameter. These data are the same as those shown in the graphical distributions, but provide a more convenient format of expressing the data. Comparing the data for both the 2015 and 4015 spray nozzles at both pressures and all three airspeeds, general trends can be observed (Table 1). The 4015 flat fan nozzle results in smaller droplet sizes than the 2015 at the same pressure and airspeed, as indicated by the smaller volume weighted diameters (DV0.1, DV0.5, and DV0.9) and the increase in the total volume of the spray comprised of droplet of 100 &#956;m or less. DV0.1, DV0.5, and DV0.9 are the droplet diameters such that 10, 50 and 90%, respectively, of the total spray volume is comprised of droplets of equal or lesser diameter. This is the result of the increase spray fan angle seeing greater breakup at the outer edges of the liquid fan angle. Within the same nozzle type and spray pressure, all droplet size metrics decrease with increasing airspeeds, again as a result of increasing breakup of droplets at the higher airspeeds. An interesting phenomenon with the aerial spray nozzles is seen when looking at the effects of spray pressure within each nozzle and airspeed combination. All else remaining equal, as pressure increases, so does droplet size11. This is caused by a decrease in the relative velocity difference between the liquid exiting the nozzle and the surrounding airstream, as the liquid exit velocity increases as pressure increases (Table 1)13.
Looking at the results from the ground nozzles and spray pressures tested, the effect of nozzle type on droplet size is significant with the TTI11003 resulting in droplet sizes that are more than double that the XRC11003 and the AI11003 droplet sizes falling in the middle of the other two (Table 2). Within each nozzle type, the effects of pressure can be observed with droplet sizes decreasing with increased spray pressure.
<img alt="Figure 1" src="/files/ftp_upload/54533/54533fig1.jpg" /> 
Figure 1. Incremental droplet size distribution for a 20 degree flat fan aerial spray nozzle with a #15 orifice operated at 207 kPa and in an airspeed of 53.6 m/sec. The blue curve represents the incremental volume weighted distribution which provides the percentage of the total spray volume contained in droplets falling with the range of each measurement bin as measured by the laser diffraction system. The red curve is the same data, but represented as cumulative data. The cumulative data allows for the volume-weighted diameters specific to a certain percentage of total spray volume to be determined. As illustrated in the figure, to obtained the DV0.5 volume diameter, locating the 50% point on the cumulative curve and the associated droplet diameter shows that 50% of the total spray volume is contained in spray droplets of diameter 551 &#956;m or smaller. <a href="http://cloudflare.jove.com/files/ftp_upload/54533/54533fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/54533/54533fig2.jpg" /> 
Figure 2. Incremental droplet size distribution for a 40 degree flat fan aerial spray nozzle with a #15 orifice operated at 207 kPa and in an airspeed of 71.5 m/sec. As in Figure 1, the blue curve represents the incremental volume weighted distribution and the red curve is the cumulative distribution. Compared to the results shown in Figure 1, the incremental distribution shows a significant shift toward smaller droplet diameters as a result of the increased airspeed and therefore secondary droplet breakup. Determining the DV0.5 volume diameter shows that 50% of this spray volume is contained in droplets of diameter 350 &#956;m or smaller. <a href="http://cloudflare.jove.com/files/ftp_upload/54533/54533fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/54533/54533fig3.jpg" /> 
Figure 3. Incremental droplet size distribution with false peak example plot. The secondary, smaller peak on the right, toward the larger end of the droplet size scale is typically the result of either vibrations or other noise in the system or the presence of ligaments associated with incomplete atomization within the spray cloud. As droplet size distributions for typical agricultural spray nozzles and solutions are typically log-normally distributed, the presence of a secondary peak in the distribution may be a valid result from an atypical spray solution and/or nozzle combination, but is more likely an indicator of some confounding issue in the measurement process. <a href="http://cloudflare.jove.com/files/ftp_upload/54533/54533fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td rowspan="2">Nozzle</td>
			<td rowspan="2">Pressure (kPa)</td>
			<td rowspan="2">Airspeed (m/sec)</td>
			<td colspan="3">Volume Weighted Diameters (&#181;m) [Mean &#177; St. Dev.]</td>
			<td rowspan="2">Percent Spray Volume Less than 100 &#956;m</td>
		</tr>
		<tr>
			<td>DV0.1</td>
			<td>DV0.5</td>
			<td>DV0.9</td>
		</tr>
		<tr>
			<td rowspan="6">2015</td>
			<td rowspan="3">207</td>
			<td>53.6</td>
			<td>243.5&#177;2.5</td>
			<td>551.8&#177;4.6</td>
			<td>903.0&#177;25.4</td>
			<td>1.4&#177;0.05</td>
		</tr>
		<tr>
			<td>62.6</td>
			<td>192.1&#177;0.5</td>
			<td>444.5&#177;1.5</td>
			<td>781.7&#177;7.0</td>
			<td>2.4&#177;0.04</td>
		</tr>
		<tr>
			<td>71.5</td>
			<td>147.0&#177;2.8</td>
			<td>350.6&#177;6.1</td>
			<td>673.3&#177;14.6</td>
			<td>4.5&#177;0.18</td>
		</tr>
		<tr>
			<td rowspan="3">414</td>
			<td>53.6</td>
			<td>289.1&#177;3.1</td>
			<td>655.6&#177;2.1</td>
			<td>1208.7&#177;11.6</td>
			<td>0.8&#177;0.03</td>
		</tr>
		<tr>
			<td>62.6</td>
			<td>237.6&#177;0.1</td>
			<td>542.7&#177;1.7</td>
			<td>1072.5&#177;13.7</td>
			<td>1.3&#177;0.01</td>
		</tr>
		<tr>
			<td>71.5</td>
			<td>170.8&#177;1.1</td>
			<td>400.6&#177;3.3</td>
			<td>732.1&#177;6.4</td>
			<td>3.2&#177;0.05</td>
		</tr>
		<tr>
			<td rowspan="6">4015</td>
			<td rowspan="3">207</td>
			<td>53.6</td>
			<td>230.2&#177;1.3</td>
			<td>514.9&#177;1.9</td>
			<td>863.3&#177;1.2</td>
			<td>1.5&#177;0.03</td>
		</tr>
		<tr>
			<td>62.6</td>
			<td>175.1&#177;2.0</td>
			<td>404.5&#177;2.6</td>
			<td>714.2&#177;3.0</td>
			<td>3.1&#177;0.10</td>
		</tr>
		<tr>
			<td>71.5</td>
			<td>146.6&#177;0.8</td>
			<td>344.5&#177;2.4</td>
			<td>656.4&#177;9.5</td>
			<td>4.6&#177;0.05</td>
		</tr>
		<tr>
			<td rowspan="3">414</td>
			<td>53.6</td>
			<td>255.2&#177;2.4</td>
			<td>557.3&#177;2.3</td>
			<td>994.9&#177;8.1</td>
			<td>1&#177;0.04</td>
		</tr>
		<tr>
			<td>62.6</td>
			<td>200.1&#177;2.6</td>
			<td>449.4&#177;7.0</td>
			<td>774.9&#177;10.7</td>
			<td>2.1&#177;0.06</td>
		</tr>
		<tr>
			<td>71.5</td>
			<td>165.5&#177;1.4</td>
			<td>383.5&#177;2.6</td>
			<td>696.8&#177;4.9</td>
			<td>3.4&#177;0.08</td>
		</tr>
	</tbody>
</table>
Table 1. Volume weighted diameters (averages&#160;&#177; standard deviations across three replicate measurements) for 2015 and 4015 flat fan aerial spray nozzles operated at spray pressures of 207 and 414 kPa and in airspeeds of 53.6, 62.6 and 71.5 m/sec.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td rowspan="2">Nozzle</td>
			<td rowspan="2">Pressure (kPa)</td>
			<td colspan="3">Volume Weighted Diameters (&#181;m) [Mean &#177; St. Dev.]</td>
			<td rowspan="2">Percent Spray Volume Less than 100 &#956;m</td>
		</tr>
		<tr>
			<td>DV0.1</td>
			<td>DV0.5</td>
			<td>DV0.9</td>
		</tr>
		<tr>
			<td rowspan="2">XRC11005</td>
			<td>276</td>
			<td>115.1&#177;2.1</td>
			<td>268.2&#177;5.6</td>
			<td>451.0&#177;18.0</td>
			<td>7.2&#177;0.28</td>
		</tr>
		<tr>
			<td>414</td>
			<td>101.0&#177;0.0</td>
			<td>244.2&#177;0.7</td>
			<td>424.3&#177;4.3</td>
			<td>9.8&#177;0.01</td>
		</tr>
		<tr>
			<td rowspan="2">AI11005</td>
			<td>276</td>
			<td>227.6&#177;1.9</td>
			<td>468.9&#177;4.1</td>
			<td>763.0&#177;22.0</td>
			<td>1.1&#177;0.03</td>
		</tr>
		<tr>
			<td>414</td>
			<td>183.4&#177;0.6</td>
			<td>399.6&#177;0.9</td>
			<td>668.6&#177;2.5</td>
			<td>2.2&#177;0.05</td>
		</tr>
		<tr>
			<td rowspan="2">TTI11005</td>
			<td>276</td>
			<td>365.3&#177;5.3</td>
			<td>711.9&#177;16.9</td>
			<td>1013.8&#177;26.1</td>
			<td>0.1&#177;0.00</td>
		</tr>
		<tr>
			<td>414</td>
			<td>311.5&#177;4.0</td>
			<td>645.7&#177;12.3</td>
			<td>992.7&#177;24.7</td>
			<td>0.2&#177;0.01</td>
		</tr>
	</tbody>
</table>
Table 2. Volume weighted diameters (averages&#160;&#177; standard deviations across three replicate measurements) for three ground sprayer nozzles (XRC11005, AI11005 and TTI11005) operated at spray pressures of 276 and 414 kPa.

Watch this Scientific Journal Video about Measuring Spray Droplet Size from Agricultural Nozzles Using Laser Diffraction at JoVE.com

Measuring Spray Droplet Size from Agricultural Nozzles Using Laser Diffraction

We present protocols to be used in the measurement of spray droplet size from agricultural nozzles used in both aerial and ground based agrochemical applications. These methods presented were developed to provide consistent and repeatable droplet size data both inter- and intra-laboratory, when using laser diffraction systems.

When making an application of any crop protection material such as an herbicide or pesticide, the applicator uses a variety of skills and information to ...

measuring-spray-droplet-size-from-agricultural-nozzles-using-laser

Research

JoVE Journal

Engineering

16.9K Views.  USDA ARS. We present protocols to be used in the measurement of spray droplet size from agricultural nozzles used in both aerial and ground based agrochemical applications. These methods presented were developed to provide consistent and repeatable droplet size data both inter- and intra-laboratory, when using laser diffraction systems.

Video: Measuring Spray Droplet Size from Agricultural Nozzles Using Laser Diffraction

Synthesis of Phase-shift Nanoemulsions with Narrow Size Distributions for Acoustic Droplet Vaporization and Bubble-enhanced Ultrasound-mediated Ablation

High-intensity focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To enhance localized heating and improve thermal ablation in tumors, lipid-coated perfluorocarbon droplets have been developed which can be vaporized by HIFU. The vasculature in many tumors is abnormally leaky due to their rapid growth, and nanoparticles are able to penetrate the fenestrations and passively accumulate within tumors. Thus, controlling the size of the droplets can result in better accumulation within tumors. In this report, the preparation of stable droplets in a phase-shift nanoemulsion (PSNE) with a narrow size distribution is described. PSNE were synthesized by sonicating a lipid solution in the presence of liquid perfluorocarbon. A narrow size distribution was obtained by extruding the PSNE multiple times using filters with pore sizes of 100 or 200 nm. The size distribution was measured over a 7-day period using dynamic light scattering. Polyacrylamide hydrogels containing PSNE were prepared for in vitro experiments. PSNE droplets in the hydrogels were vaporized with ultrasound and the resulting bubbles enhanced localized heating. Vaporized PSNE enables more rapid heating and also reduces the ultrasound intensity needed for thermal ablation. Thus, PSNE is expected to enhance thermal ablation in tumors, potentially improving therapeutic outcomes of HIFU-mediated thermal ablation treatments.

Phase-shift nanoemulsions (PSNE) can be vaporized using high intensity focused ultrasound to enhance localized heating and improve thermal ablation in tumors. In this report, the preparation of stable PSNE with a narrow size distribution is described. Furthermore, the impact of vaporized PSNE on ultrasound-mediated ablation is demonstrated in tissue-mimicking phantoms.

High-intensity  focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To  enhance localized heating and improve thermal ablation in ...

Measuring Spatially- and Directionally-varying Light Scattering from Biological Material

Light interacts with an organism's integument on a variety of spatial scales. For example in an iridescent bird: nano-scale structures produce color; the milli-scale structure of barbs and barbules largely determines the directional pattern of reflected light; and through the macro-scale spatial structure of overlapping, curved feathers, these directional effects create the visual texture. Milli-scale and macro-scale effects determine where on the organism's body, and from what viewpoints and under what illumination, the iridescent colors are seen. Thus, the highly directional flash of brilliant color from the iridescent throat of a hummingbird is inadequately explained by its nano-scale structure alone and questions remain. From a given observation point, which milli-scale elements of the feather are oriented to reflect strongly? Do some species produce broader "windows" for observation of iridescence than others? These and similar questions may be asked about any organisms that have evolved a particular surface appearance for signaling, camouflage, or other reasons.
In order to study the directional patterns of light scattering from feathers, and their relationship to the bird's milli-scale morphology, we developed a protocol for measuring light scattered from biological materials using many high-resolution photographs taken with varying illumination and viewing directions. Since we measure scattered light as a function of direction, we can observe the characteristic features in the directional distribution of light scattered from that particular feather, and because barbs and barbules are resolved in our images, we can clearly attribute the directional features to these different milli-scale structures. Keeping the specimen intact preserves the gross-scale scattering behavior seen in nature. The method described here presents a generalized protocol for analyzing spatially- and directionally-varying light scattering from complex biological materials at multiple structural scales.

We present a non-destructive method for sampling spatial variation in the direction of light scattered from structurally complex materials. By keeping the material intact, we preserve gross-scale scattering behavior, while concurrently capturing fine-scale directional contributions with high-resolution imaging. Results are visualized in software at biologically-relevant positions and scales.

Light interacts with an organism's integument on a variety of spatial scales. For example in an iridescent bird: nano-scale structures produce color; the ...

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric vehicles.1,2 However, many challenges, such as energy density and battery lifetimes, need to be overcome before this particular battery technology can be widely implemented in such applications.3 This research is challenging, and we outline a method to address these challenges using in situ NPD to probe the crystal structure of electrodes undergoing electrochemical cycling (charge/discharge) in a battery. NPD data help determine the underlying structural mechanism responsible for a range of electrode properties, and this information can direct the development of better electrodes and batteries.
We briefly review six types of battery designs custom-made for NPD experiments and detail the method to construct the &#8216;roll-over&#8217; cell that we have successfully used on the high-intensity NPD instrument, WOMBAT, at the Australian Nuclear Science and Technology Organisation (ANSTO). The design considerations and materials used for cell construction are discussed in conjunction with aspects of the actual in situ NPD experiment and initial directions are presented on how to analyze such complex in situ data.

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

We describe the design and construction of an electrochemical cell for the examination of electrode materials using in situ neutron powder diffraction (NPD). We briefly comment on alternate in situ NPD cell designs and discuss methods for the analysis of the corresponding in situ NPD data produced using this cell.

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric ...

Characterization of Nanocrystal Size Distribution using Raman Spectroscopy with a Multi-particle Phonon Confinement Model

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The common techniques used for the size analysis are transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). These techniques, however, are not suitable for analyzing the nanocrystal size distribution in a fast, non-destructive and a reliable manner at the same time. Our aim in this work is to demonstrate that size distribution of semiconductor nanocrystals that are subject to size-dependent phonon confinement effects, can be quantitatively estimated in a non-destructive, fast and reliable manner using Raman spectroscopy. Moreover, mixed size distributions can be separately probed, and their respective volumetric ratios can be estimated using this technique. In order to analyze the size distribution, we have formulized an analytical expression of one-particle PCM and projected it onto a generic distribution function that will represent the size distribution of analyzed nanocrystal. As a model experiment, we have analyzed the size distribution of free-standing silicon nanocrystals (Si-NCs) with multi-modal size distributions. The estimated size distributions are in excellent agreement with TEM and PL results, revealing the reliability of our model.

We demonstrate how to determine the size distribution of semiconductor nanocrystals in a quantitative manner using Raman spectroscopy employing an analytically defined multi-particle phonon confinement model. Results obtained are in excellent agreement with the other size analysis techniques like transmission electron microscopy and photoluminescence spectroscopy.

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The ...

Compact Lens-less Digital Holographic Microscope for MEMS Inspection and Characterization

A micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and automotive. However, effective inspection and characterization metrology systems are needed to ensure the functional reliability of MEMS. This study presents a system based on digital holography as a tool for MEMS metrology. Digital holography has gained increasing attention in the past 20 years. With the fast development and decreasing cost of sensor arrays, resolution of such systems has increased broadening potential applications. Thus, it has attracted attention from both research and industry sides as a potential reliable tool for industrial metrology. Indeed, by recording the interference pattern between an object beam (which contains sample height information) and a reference beam on a CCD camera, one can retrieve the quantitative phase information of an object. However, most of digital holographic systems are bulky and thus not easy to implement on industry production lines. The novelty of the system presented is that it is lens-less and thus very compact. In this study, it is shown that the Compact Digital Holographic Microscope (CDHM) can be used to evaluate several characteristics typically consider as criteria in MEMS inspections. The surface profiles of MEMS in both static and dynamic conditions are presented. Comparison with AFM is investigated to validate the accuracy of the CDHM.

We present a compact reflection digital holographic system (CDHM) for inspection and characterization of MEMS devices. A lens-less design using a diverging input wave providing natural geometrical magnification is demonstrated. Both static and dynamic studies are presented.

A micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and ...

Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques.

A protocol to detect and automate mode locking in a pre-adjusted nonlinear polarization rotation fiber laser is presented. The detection of a sudden change in the output polarization state when mode locking occurs is used to command the alignment of an intra-cavity polarization controller in order to find mode-locking conditions.

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a ...

Characterization of Ultra-fine Grained and Nanocrystalline Materials Using Transmission Kikuchi Diffraction

One of the challenges in microstructure analysis nowadays resides in the reliable and accurate characterization of ultra-fine grained (UFG) and nanocrystalline materials. The traditional techniques associated with scanning electron microscopy (SEM), such as electron backscatter diffraction (EBSD), do not possess the required spatial resolution due to the large interaction volume between the electrons from the beam and the atoms of the material. Transmission electron microscopy (TEM) has the required spatial resolution. However, due to a lack of automation in the analysis system, the rate of data acquisition is slow which limits the area of the specimen that can be characterized. This paper presents a new characterization technique, Transmission Kikuchi Diffraction (TKD), which enables the analysis of the microstructure of UFG and nanocrystalline materials using an SEM equipped with a standard EBSD system. The spatial resolution of this technique can reach 2 nm. This technique can be applied to a large range of materials that would be difficult to analyze using traditional EBSD. After presenting the experimental set up and describing the different steps necessary to realize a TKD analysis, examples of its use on metal alloys and minerals are shown to illustrate the resolution of the technique and its flexibility in term of material to be characterized.

This paper provides a detailed method to characterize the microstructure of ultra-fine grained and nanocrystalline materials using a scanning electron microscope equipped with a standard electron backscatter diffraction system. Metal alloys and minerals presenting refined microstructures are analyzed using this technique, showing the diversity of its possible applications.

One of the challenges in microstructure analysis nowadays resides in the reliable and accurate characterization of ultra-fine grained (UFG) and ...

Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering thermal wave fields that are disturbed by the defect. This effect is measured and used to locate the defect. We form the destructively interfering wave fields by using a modified projector. The original light engine of the projector is replaced with a fiber-coupled high-power diode laser. Its beam is shaped and aligned to the projector&#39;s spatial light modulator and optimized for optimal optical throughput and homogeneous projection by first characterizing the beam profile, and, second, correcting it mechanically and numerically. A high-performance infrared (IR) camera is set up according to the tight geometrical situation (including corrections of the geometrical image distortions) and the requirement to detect weak temperature oscillations at the sample surface. Data acquisition can be performed once a synchronization between the individual thermal wave field sources, the scanning stage, and the IR camera is established by using a dedicated experimental setup which needs to be tuned to the specific material being investigated. During data post-processing, the relevant information on the presence of a defect below the surface of the sample is extracted. It is retrieved from the oscillating part of the acquired thermal radiation coming from the so-called depletion line of the sample surface. The exact location of the defect is deduced from the analysis of the spatial-temporal shape of these oscillations in a final step. The method is reference-free and very sensitive to changes within the thermal wave field. So far, the method has been tested with steel samples but is applicable to different materials as well, in particular to temperature sensitive materials.

This method aims at locating vertical subsurface defects. Here, we couple a laser with a spatial light modulator and trigger its video input to heat a sample surface deterministically with two anti-phased modulated lines while acquiring highly resolved thermal images. The defect position is retrieved from evaluating thermal wave interference minima.

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering ...

Fourier-Based Diffraction Analysis of Live Caenorhabditis elegans

This manuscript describes how to classify nematodes using temporal far-field diffraction signatures. A single C. elegans is suspended in a water column inside an optical cuvette. A 632 nm continuous wave HeNe laser is directed through the cuvette using front surface mirrors. A significant distance of at least 20-30 cm traveled after the light passes through the cuvette ensures a useful far-field (Fraunhofer) diffraction pattern. The diffraction pattern changes in real time as the nematode swims within the laser beam. The photodiode is placed off-center in the diffraction pattern. The voltage signal from the photodiode is observed in real time and recorded using a digital oscilloscope. This process is repeated for 139 wild type and 108 &#34;roller&#34; C. elegans. Wild type worms exhibit a rapid oscillation pattern in solution. The &#34;roller&#34; worms have a mutation in a key component of the cuticle that interferes with smooth locomotion. Time intervals that are not free of saturation and inactivity are discarded. It is practical to divide each average by its maximum to compare relative intensities. The signal for each worm is Fourier transformed so that the frequency pattern for each worm emerges. The signal for each type of worm is averaged. The averaged Fourier spectra for the wild type and the &#34;roller&#34; C. elegans are distinctly different and reveal that the dynamic worm shapes of the two different worm strains can be distinguished using Fourier analysis. The Fourier spectra of each worm strain match an approximate model using two different binary worm shapes that correspond to locomotory moments. The envelope of the averaged frequency distribution for actual and modeled worms confirms the model matches the data. This method can serve as a baseline for Fourier analysis for many microscopic species, as every microorganism will have its unique Fourier spectrum.

Fourier-Based Diffraction Analysis of Live Caenorhabditis elegans

This manuscript describes how to distinguish different nematodes using far-field diffraction signatures. We compare the locomotion of 139 wild type and 108 &#34;Roller&#34; C. elegans by averaging frequencies associated with the temporal Fraunhofer diffraction signature at a single location using a continuous wave laser.

This manuscript describes how to classify nematodes using temporal far-field diffraction signatures. A single C. elegans is suspended in a water column ...

Femtosecond Laser Filaments for Use in Sub-Diffraction-Limited Imaging and Remote Sensing

Probing remote matter with laser light is a ubiquitous technique used in circumstances as diverse as laser-induced breakdown spectroscopy and barcode scanners. In classical optics, the intensity that can be brought to bear on a remote target is limited by the spot size of the laser at the distance of the target. This spot size has a lower bound determined by the diffraction limit of classical optics. However, amplified femtosecond laser pulses generate intensity sufficient to modify the refractive index of the ambient air and undergo self-focusing. This self-focusing effect leads to the generation of highly intense laser filaments which maintain their intensity and small sub-millimeter diameter size at distances well beyond the classical Rayleigh length. Such intensity provides the capability of remote scanning, imaging, sensing, and spectroscopy with enhanced spatial resolution. We describe a technique for generating filaments with a femtosecond regenerative chirped-pulse amplifier, and for using the resulting filament to conduct imaging and spectroscopic measurements at remote distances of at least several meters.

High-intensity femtosecond pulses of laser light can undergo cycles of Kerr self-focusing and plasma defocusing, propagating an intense sub-millimeter-diameter beam over long distances. We describe a technique for generating and using these filaments to perform remote imaging and sensing beyond the classical diffraction limits of linear optics.

Probing remote matter with laser light is a ubiquitous technique used in circumstances as diverse as laser-induced breakdown spectroscopy and barcode ...

Measuring Spray Droplet Size from Agricultural Nozzles Using Laser Diffraction

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Fourier-Based Diffraction Analysis of Live Caenorhabditis elegans

Femtosecond Laser Filaments for Use in Sub-Diffraction-Limited Imaging and Remote Sensing