1. Setup Alignment
<ol>
	<li>Start by roughly aligning the laser, the beam expender, the lens, and the camera on the same axis; this would be the optic axis.</li>
	<li>Turn on the laser (without the USAT target), and make sure that the light passes through the center of the lens. Use an aperture iris to verify.</li>
	<li>Turn on the camera, and make sure that the light focuses on the center of the camera.</li>
	<li>Shift back the camera, using the linear z stage. Since the system is going out of focus, the spot of light will grow. Make sure that the center of the spot remains in the same lateral position. If not, carefully change the position of the imaging system and repeat this step until the spot remains at the same spatial position, up to a pixel level.</li>
</ol>
2. Imaging at Three Defocus Planes
<ol>
	<li>Insert the test target in front of the beam expender. Place the target so that the light that passes through it will pass through the center of the lens.</li>
	<li>Capture an image. This image will be an anchor point, and its location will be z0,x0 (all the other images will be in reference to its location). This image will be I1,b.</li>
	<li>Shift back the camera (using the linear z stage) a distance of dz = 5.08 mm (or 0.2 in) and capture an image. This image will be I2,b.</li>
	<li>Shift back the camera another distance of dz = 5.08 mm (10.16 mm relative to z0) and capture an image. This image will be I3,b.</li>
	<li>Go back to z0.</li>
</ol>
3. Scanning the Aperture
<ol>
	<li>Shift the entire imaging system laterally (using the linear x stage) a distance of dx = 2.5 mm and capture an image. This image will be I1,a.</li>
	<li>Repeat the process in&#160;Protocol 2. Shift back the camera (using the linear z stage) a distance of dz = 5.08 mm, and capture an image (I2,a). Shift back the camera another distance of dz = 5.08 mm, and capture an image (I3,a).</li>
	<li>Now, repeat the procedure for the other side. Shift the imaging system a distance of dx = -2.5 mm and capture a set of three images in three z positions (I1-3,c).</li>
	<li>Go back to z0,x0.</li>
</ol>
4. Phase Retrieval (Numerical Calculation)
<ol>
	<li>Using the three planes method14, and images I1-3,b, retrieve the optical phase of image I1,b.Using the phase that was retrieved, define q1,b.</li>
	<li>Monitor the correlation coefficient between I1,b and |q1,b|2, in order to verify that the iterative process does converge. To do so, use the &#39;corr2&#39; function in MATLAB.</li>
	<li>Repeat the phase retrieval process for I1-3,a, and I1-3,c.</li>
</ol>
5. Super Resolved Image (Numerical Calculation)
<ol>
	<li>Using Fresnel free space propagation (FSP) integral15, back propagate the fields q1,a-c to the lens plane. These fields will be &#202;lens,a-c+.</li>
	<li>Multiply the resulting fields &#202;lens,a-c+ by exp(+&#960;ix02)/&#955;f), in order to pass back through the lens. These fields will be &#202;lens,a-c-.</li>
	<li>In order to place the field &#202;lens,a in its original position, shift it laterally a distance of dx = 2.5 mm.</li>
	<li>In order to place the field &#202;lens,c in its original position, shift it laterally a distance of dx = -2.5 mm.</li>
	<li>Sum the three fields &#202;lens,a-c, in order to combine them, and synthetically increase the aperture size.</li>
	<li>Multiply the resulting field by exp(-&#960;ix02)/&#955;f), and free space propagate it to image plane.</li>
	<li>A resolution improvement by a factor of 3 in the scanning direction should be witnessed.</li>
</ol>

<ol>
	<li>De Loor, G. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Possibilities+and+uses+of+radar+and+thermal+infrared+systems.">Possibilities and uses of radar and thermal infrared systems.</a> Photogrammetria. 24, 43-58 (1969).</li><li>Simonett, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remote+sensing+with+imaging+radar:+A+review.">Remote sensing with imaging radar: A review.</a> Geoforum. , 61-74 (1970).</li><li>Born, M., Wolf, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Principles of optics: electromagnetic theory of propagation, interference and diffraction of light. , (1999).</li><li>Wiley, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+aperture+radars-a+paradigm+for+technology+evolution.">Synthetic aperture radars-a paradigm for technology evolution.</a> IEEE Trans. Aerospace Elec. Sys. 21, 440-443 (1985).</li><li>Brown, W., Porcello, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> An introduction to synthetic-aperture radar. , 52-62 (1969).</li><li>Cheney, M., Borden, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fundamentals of Radar Imaging. Siam. , (2008).</li><li>Otto, R., Fritz, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Die+lehre+von+der+bildentstehung+im+mikroskop+von+Ernst+Abbe.">Die lehre von der bildentstehung im mikroskop von Ernst Abbe.</a> Vieweg Braunschweig. , (1910).</li><li>Gerchberg, W. R., Saxton, W. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+practical+algorithm+for+the+determination+of+phase+from+image+and+diffraction+plane+pictures.">A practical algorithm for the determination of phase from image and diffraction plane pictures.</a> Optik. 35, 237-246 (1972).</li><li>Misell, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+for+the+solution+of+the+phase+problem+in+electron+microscopy.">A method for the solution of the phase problem in electron microscopy.</a> J. Phys. D Appl. Phys. 6, (1973).</li><li>Misell, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+examination+of+an+iterative+method+for+the+solution+of+the+phase+problem+in+optics+and+electron+optics:+I.+Test+calculations.">An examination of an iterative method for the solution of the phase problem in optics and electron optics: I. Test calculations.</a> J. Phys. D Appl. Phys. 6, 2200-2216 (1973).</li><li>Misell, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+examination+of+an+iterative+method+for+the+solution+of+the+phase+problem+in+optics+and+electron+optics.">An examination of an iterative method for the solution of the phase problem in optics and electron optics.</a> II. Sources of error. J. Phys. D Appl. Phys. 6, 2217-2225 (1973).</li><li>Fienup, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reconstruction+of+an+object+from+the+modulus+of+its+Fourier+transform.">Reconstruction of an object from the modulus of its Fourier transform.</a> Optics Lett. 3, 27-29 (1978).</li><li>Fienup, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phase+retrieval+algorithms:+a+comparison.">Phase retrieval algorithms: a comparison.</a> Appl. Optics. 21, 2758-2769 (1982).</li><li>Gur, E., Zalevsky, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Image+deblurring+through+static+or+time-varying+random+perturbation+medium.">Image deblurring through static or time-varying random perturbation medium.</a> J. Electron. Imaging. 18, 033016-03 (2009).</li><li>Goodman, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Introduction+to+Fourier+Optics.">Introduction to Fourier Optics.</a> Roberts &amp; Company. , (2005).</li><li>Tippie, A. E., Kumar, A., Fienup, J. 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There is nothing to disclose.

The optical synthetic aperture RADAR (OSAR) concept that is presented in this paper is a new super resolved approach that uses the G-S algorithm and scanning technique in order to improve the spatial resolution of an object in the direction of the scan. The movement of the imaging platform can be self-generated while using an airborne or satellite platform. Unlike many time multiplexing SR techniques, our method does not require any a priori information of the object, other than the fact that it is stationary du...

In radar imaging, a narrow angle beam of pulse Radio Frequency (RF) is transmitted using an antenna that is mounted on a platform. The radar signal transmits in a side-looking direction towards the surface1,2. The reflected signal is backscattered from the surface and is received by the same antenna2. The received signals are converted to a radar image. In Real Aperture Radar (RAR) the resolution in the azimuth direction is proportional to wavelength and inversely proportional to the aperture dimension3. Thus, a bigger antenna is required for higher azimuth resolution. However, it is difficult to attach large antenna to a moving platforms such as airplanes and satellites. In 1951 Wiley4 suggested a new radar technique called Synthetic Aperture Radar (SAR), which uses the Doppler effect created by the movement of the imaging platform. In SAR, the amplitude as well as the phase of the received signal are recorded5. This is possible since the SAR optical frequency is about 1-100 GHz6 and the phase is recorded using a reference local resonator installed on top of the platform. In optical imaging, shorter wavelengths are being used, such as the visible and the near infra-red (NIR), which is about 1 &#956;m, i.e. frequency of about 1014&#160;Hz. The field intensity, rather than the field itself, is being detected since the optic phase changes too fast for detection using standard silicon based detectors.
While imaging an object through an optical system, the aperture of the optics serves as a low-pass filter. Thus, the high-frequency spatial information of the object is lost7. In this paper we aim to solve each of the above mentioned issues separately, i.e. the phase lost and the diffraction limit effect.
Gerchberg and Saxton (G-S)8 suggested that the optical phase can be retrieved using an iterative process. Misell9-11 has extended the algorithm for any two input and output planes. These approaches are proven to converge to a phase distribution with a minimal mean square error (MSE)12,13. Gur and Zalevsky14 presented a three planes method which improves the Misell algorithm.
We propose and demonstrate experimentally that restoring the phase while shifting the imaging lens, as done with the antenna in SAR application allows us to synthetically increase the effective size of the aperture along the scanning axis and eventually improve the resulted imaging resolution.
The application of SAR in optical imaging using interferometry and holography is well-known16,17. However, the suggested method is aimed for mimicking a scanning imaging platform, making it suitable for noncoherent imaging (such as side-looking airborne platform). Thus, the concept of holography, which uses a reference beam, is not suitable for such an application. Instead, the revised Gerchberg-Saxton algorithm is used in order to retrieve the phase.

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	<tbody>
		<tr height="22">
			<td align="left" height="22" style="height:22px;width:311px;">Red Laser Module</td>
			<td style="width:311px;">Thorlabs</td>
			<td style="width:259px;"><a href="http://thorlabs.com/thorProduct.cfm?partNumber=LDM635">LDM635</a></td>
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		</tr>
		<tr height="22">
			<td align="left" height="22" style="height:22px;width:311px;">10X Galilean Beam Expander</td>
			<td style="width:311px;">Thorlabs</td>
			<td style="width:259px;"><a href="http://thorlabs.com/thorProduct.cfm?partNumber=BE10M-A">BE10M-A</a></td>
			<td style="width:261px;"></td>
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			<td align="left" height="22" style="height:22px;width:311px;">Negative 1951 USAF Test Target</td>
			<td style="width:311px;">Thorlabs</td>
			<td style="width:259px;"><a href="http://thorlabs.com/thorProduct.cfm?partNumber=R3L3S1N">R3L3S1N</a></td>
			<td style="width:261px;"></td>
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			<td align="left" height="22" style="height:22px;width:311px;">Filter holder for 2&#34; Square Filters</td>
			<td style="width:311px;">Thorlabs</td>
			<td style="width:259px;"><a href="http://thorlabs.com/thorProduct.cfm?partNumber=FH2">FH2</a></td>
			<td style="width:261px;"></td>
		</tr>
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			<td align="left" height="22" style="height:22px;width:311px;">1&#34; Linear Translation Stage</td>
			<td style="width:311px;">Thorlabs</td>
			<td style="width:259px;"><a href="http://thorlabs.com/thorProduct.cfm?partNumber=PT1">PT1</a></td>
			<td style="width:261px;">X2</td>
		</tr>
		<tr height="22">
			<td align="left" height="22" style="height:22px;width:311px;">Lens Mount for &#216;1&#34; Optics</td>
			<td style="width:311px;">Thorlabs</td>
			<td style="width:259px;"><a href="http://thorlabs.com/thorProduct.cfm?partNumber=LMR1">LMR1</a></td>
			<td style="width:261px;"></td>
		</tr>
		<tr height="22">
			<td align="left" height="22" style="height:22px;width:311px;">Lens f = 100.0mm</td>
			<td style="width:311px;">Thorlabs</td>
			<td style="width:259px;"><a href="http://thorlabs.com/thorProduct.cfm?partNumber=AC254-100-A">AC254-100-A</a></td>
			<td style="width:261px;"></td>
		</tr>
		<tr height="22">
			<td align="left" height="22" style="height:22px;width:311px;">Graduated Ring-Activated Iris Diaphragm</td>
			<td style="width:311px;">Thorlabs</td>
			<td style="width:259px;"><a href="http://www.thorlabs.com/thorproduct.cfm?partnumber=SM1D12C">SM1D12C</a></td>
			<td style="width:261px;"></td>
		</tr>
		<tr height="22">
			<td align="left" height="22" style="height:22px;width:311px;">2.5x2.5mm Aperture &#216;1&#34;</td>
			<td style="width:311px;"></td>
			<td style="width:259px;"></td>
			<td style="width:261px;">Indoor production</td>
		</tr>
		<tr height="22">
			<td align="left" height="22" style="height:22px;width:311px;">High Resolution CMOS Camera</td>
			<td style="width:311px;">Thorlabs</td>
			<td style="width:259px;"><a href="http://thorlabs.com/thorProduct.cfm?partNumber=DCC1545M">DCC1545M</a></td>
			<td style="width:261px;"></td>
		</tr>
	</tbody>
</table>

time multiplexing super resolving technique for imaging from a moving platform

We propose a method for increasing the resolution of an object and overcoming the diffraction limit of an optical system installed on top of a moving imaging system, such as an airborne platform or satellite. The resolution improvement is obtained in a two-step process. First, three low resolution differently defocused images are being captured and the optical phase is retrieved using an improved iterative Gerchberg-Saxton based algorithm. The phase retrieval allows to numerically back propagate the field to the aperture plane. Second, the imaging system is shifted and the first step is repeated. The obtained optical fields at the aperture plane are combined and a synthetically increased lens aperture is generated along the direction of movement, yielding higher imaging resolution. The method resembles a well-known approach from the microwave regime called the Synthetic Aperture Radar (SAR) in which the antenna size is synthetically increased along the platform propagation direction. The proposed method is demonstrated through laboratory experiment.

An example for the nine captured images (three defocus images in three lateral positions) is shown in Figure 3.
An example for the G-S convergence is shown in Figure 4. The correlation coefficient for the central image I1,b is above 0.95, and the correlation coefficient for the side images I1,a, and I1,c is above 0.85 (in full numerical simulation they all passed 0.99).
A representative result for th...

Watch this Scientific Journal Video about Time Multiplexing Super Resolving Technique for Imaging from a Moving Platform at JoVE.com

Time Multiplexing Super Resolving Technique for Imaging from a Moving Platform

A method for overcoming the optical diffraction limit is presented. The method includes a two-step process: optical phase retrieval using iterative Gerchberg-Saxton algorithm, and imaging system shifting followed by repetition of the first step. A synthetically increased lens aperture is generated along the direction of movement, yielding higher imaging resolution.

We propose a method for increasing the resolution of an object and overcoming the diffraction limit of an optical system installed on top of a moving ...

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8.4K Views.  Bar-Ilan University. A method for overcoming the optical diffraction limit is presented. The method includes a two-step process: optical phase retrieval using iterative Gerchberg-Saxton algorithm, and imaging system shifting followed by repetition of the first step. A synthetically increased lens aperture is generated along the direction of movement, yielding higher imaging resolution.

Video: Time Multiplexing Super Resolving Technique for Imaging from a Moving Platform

Visualization of High Speed Liquid Jet Impaction on a Moving Surface

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds between 0 and 25 m/sec) and a spinning disk device (for examining surface speeds between 15 and 100 m/sec). The air cannon linear traverse is a pneumatic energy-powered system that is designed to accelerate a metal rail surface mounted on top of a wooden projectile. A pressurized cylinder fitted with a solenoid valve rapidly releases pressurized air into the barrel, forcing the projectile down the cannon barrel. The projectile travels beneath a spray nozzle, which impinges a liquid jet onto its metal upper surface, and the projectile then hits a stopping mechanism. A camera records the jet impingement, and a pressure transducer records the spray nozzle backpressure. The spinning disk set-up consists of a steel disk that reaches speeds of 500 to 3,000 rpm via a variable frequency drive (VFD) motor. A spray system similar to that of the air cannon generates a liquid jet that impinges onto the spinning disc, and cameras placed at several optical access points record the jet impingement. Video recordings of jet impingement processes are recorded and examined to determine whether the outcome of impingement is splash, splatter, or deposition. The apparatuses are the first that involve the high speed impingement of low-Reynolds-number liquid jets on high speed moving surfaces. In addition to its rail industry applications, the described technique may be used for technical and industrial purposes such as steelmaking and may be relevant to high-speed 3D printing.

Two experimental devices for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device and a spinning disk device. The apparatuses are used to determine optimal approaches to the application of liquid friction modifier (LFM) onto rail tracks for top-of-rail friction control.

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds ...

Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus have potential applications in nonlinear optics, which requires extraordinary optical intensity. One of the most studied nonlinearities in plasmonics is nonlinear absorption, including saturation and reverse saturation behaviors. Although scattering and absorption in nanoparticles are closely correlated by the Mie theory, there has been no report of nonlinearities in plasmonic scattering until very recently. 
Last year, not only saturation, but also reverse saturation of scattering in an isolated plasmonic particle was demonstrated for the first time. The results showed that saturable scattering exhibits clear wavelength dependence, which seems to be directly linked to the localized surface plasmon resonance (LSPR). Combined with the intensity-dependent measurements, the results suggest the possibility of a common mechanism underlying the nonlinear behaviors of scattering and absorption. These nonlinearities of scattering from a single gold nanosphere (GNS) are widely applicable, including in super-resolution microscopy and optical switches. 
In this paper, it is described in detail how to measure nonlinearity of scattering in a single GNP and how to employ the super-resolution technique to enhance the optical imaging resolution based on saturable scattering. This discovery features the first super-resolution microscopy based on nonlinear scattering, which is a novel non-bleaching contrast method that can achieve a resolution as low as l/8 and will potentially be useful in biomedicine and material studies.

Saturable and reverse saturable scattering were discovered in isolated plasmonic particles and adopted as a novel non-bleaching contrast method in super-resolution microscopy. Here the experimental procedures of detecting and extracting nonlinear scattering are explained in detail, as well as how to enhance resolution with the aid of saturated excitation microscopy.

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus ...

Use of a Multi-compartment Dynamic Single Enzyme Phantom for Studies of Hyperpolarized Magnetic Resonance Agents

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due to fundamental constraints imposed by the hyperpolarized state, exotic imaging and reconstruction techniques are commonly used. A practical system for characterization of dynamic, multi-spectral imaging methods is critically needed. Such a system must reproducibly recapitulate the relevant chemical dynamics of normal and pathological tissues. The most widely utilized substrate to date is hyperpolarized [1-13C]-pyruvate for assessment of cancer metabolism. We describe an enzyme-based phantom system that mediates the conversion of pyruvate to lactate. The reaction is initiated by injection of the hyperpolarized agent into multiple chambers within the phantom, each of which contains varying concentrations of reagents that control the reaction rate. Multiple compartments are necessary to ensure that imaging sequences faithfully capture the spatial and metabolic heterogeneity of tissue. This system will aid the development and validation of advanced imaging strategies by providing chemical dynamics that are not available from conventional phantoms, as well as control and reproducibility that is not possible in vivo.

A multi-compartment dynamic phantom is used to simulate some biology of interest for metabolic studies using hyperpolarized magnet resonance agents.

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due ...

A High Performance Impedance-based Platform for Evaporation Rate Detection

This paper describes the method of a novel impedance-based platform for the detection of the evaporation rate. The model compound hyaluronic acid was employed here for demonstration purposes. Multiple evaporation tests on the model compound as a humectant with various concentrations in solutions were conducted for comparison purposes. A conventional weight loss approach is known as the most straightforward, but time-consuming, measurement technique for evaporation rate detection. Yet, a clear disadvantage is that a large volume of sample is required and multiple sample tests cannot be conducted at the same time. For the first time in literature, an electrical impedance sensing chip is successfully applied to a real-time evaporation investigation in a time sharing, continuous and automatic manner. Moreover, as little as 0.5 ml of test samples is required in this impedance-based apparatus, and a large impedance variation is demonstrated among various dilute solutions. The proposed high-sensitivity and fast-response impedance sensing system is found to outperform a conventional weight loss approach in terms of evaporation rate detection.

This paper presents an impedance-based apparatus for evaporation rate detection of solutions. It offers clear advantages over a conventional weight loss approach: a fast response, high-sensitivity detection, a small sample requirement, multiple sample measurements, and easy disassembly for cleaning and reuse purposes.

This paper describes the method of a novel impedance-based platform for the detection of the evaporation rate. The model compound hyaluronic acid was ...

A Robotic Platform to Study the Foreflipper of the California Sea Lion

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most of their thrust with their large foreflippers. This protocol describes a robotic platform designed to study the hydrodynamic performance of the swimming California sea lion (Zalophus californianus). The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;). The kinematics of the sea lion&#39;s propulsive stroke are extracted from video data of unmarked, non-research sea lions at the Smithsonian Zoological Park (SNZ). Those data form the basis of the actuation motion of the robotic flipper presented here. The geometry of the robotic flipper is based a on high-resolution laser scan of a foreflipper of an adult female sea lion, scaled to about 60% of the full-scale flipper. The articulated model has three joints, mimicking the elbow, wrist and knuckle joint of the sea lion foreflipper. The robotic platform matches dynamics properties&#8212;Reynolds number and tip speed&#8212;of the animal when accelerating from rest. The robotic flipper can be used to determine the performance (forces and torques) and resulting flowfields.

A robotic platform is described that will be used to study the hydrodynamic performance&#8212;forces and flowfields&#8212;of the swimming California sea lion. The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;).

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most ...

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy (ATOM)

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the main trend in the advanced development of flow cytometry. Notably, adding high-resolution imaging capabilities allows for the complex morphological analysis of cellular/sub-cellular structures. This is not possible with standard flow cytometers. However, it is valuable for advancing our knowledge of cellular functions and can benefit life science research, clinical diagnostics, and environmental monitoring. Incorporating imaging capabilities into flow cytometry compromises the assay throughput, primarily due to the limitations on speed and sensitivity in the camera technologies. To overcome this speed or throughput challenge facing imaging flow cytometry while preserving the image quality, asymmetric-detection time-stretch optical microscopy (ATOM) has been demonstrated to enable high-contrast, single-cell imaging with sub-cellular resolution, at an imaging throughput as high as 100,000 cells/s. Based on the imaging concept of conventional time-stretch imaging, which relies on all-optical image encoding and retrieval through the use of ultrafast broadband laser pulses, ATOM further advances imaging performance by enhancing the image contrast of unlabeled/unstained cells. This is achieved by accessing the phase-gradient information of the cells, which is spectrally encoded into single-shot broadband pulses. Hence, ATOM is particularly advantageous in high-throughput measurements of single-cell morphology and texture &#8211; information indicative of cell types, states, and even functions. Ultimately, this could become a powerful imaging flow cytometry platform for the biophysical phenotyping of cells, complementing the current state-of-the-art biochemical-marker-based cellular assay. This work describes a protocol to establish the key modules of an ATOM system (from optical frontend to data processing and visualization backend), as well as the workflow of imaging flow cytometry based on ATOM, using human cells and micro-algae as the examples.

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy ATOM

This protocol describes the implementation of an asymmetric-detection time-stretch optical microscopy system for single-cell imaging in ultrafast microfluidic flow and its applications in imaging flow cytometry.

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the ...

Demonstration of a Hyperlens-integrated Microscope and Super-resolution Imaging

The use of super-resolution imaging to overcome the diffraction limit of conventional microscopy has attracted the interest of researchers in biology and nanotechnology. Although near-field scanning microscopy and superlenses have improved the resolution in the near-field region, far-field imaging in real-time remains a significant challenge. Recently, the hyperlens, which magnifies and converts evanescent waves into propagating waves, has emerged as a novel approach to far-field imaging. Here, we report the fabrication of a spherical hyperlens composed of alternating silver (Ag) and titanium oxide (TiO2) thin layers. Unlike a conventional cylindrical hyperlens, the spherical hyperlens allows for two-dimensional magnification. Thus, incorporation into conventional microscopy is straightforward. A new optical system integrated with the hyperlens is proposed, allowing for a sub-wavelength image to be obtained in the far-field region in real time. In this study, the fabrication and imaging setup methods are explained in detail. This work also describes the accessibility and possibility of the hyperlens, as well as practical applications of real-time imaging in living cells, which can lead to a revolution in biology and nanotechnology.

The use of a hyperlens has been regarded as a novel super-resolution imaging technique due to its advantages in real-time imaging and its simple implementation with conventional optics. Here, we present a protocol describing the fabrication and imaging applications of a spherical hyperlens.

The use of super-resolution imaging to overcome the diffraction limit of conventional microscopy has attracted the interest of researchers in biology and ...

Multiplexing Focused Ultrasound Stimulation with Fluorescence Microscopy

By focusing low-intensity ultrasound pulses that penetrate soft tissues, LIPUS represents a promising biomedical technology to remotely and safely manipulate neural firing, hormonal secretion and genetically-reprogrammed cells. However, the translation of this technology for medical applications is currently hampered by a lack of biophysical mechanisms by which targeted tissues sense and respond to LIPUS. A suitable approach to identify these mechanisms would be to use optical biosensors in combination with LIPUS to determine underlying signaling pathways. However, implementing LIPUS to a fluorescence microscope may introduce undesired mechanical artefacts due to the presence of physical interfaces that reflect, absorb and refract acoustic waves. This article presents a step-by-step procedure to incorporate LIPUS to commercially-available upright epi-fluorescence microscopes while minimizing the influence of physical interfaces along the acoustic path. A simple procedure is described to operate a single-element ultrasound transducer and to bring the focal zone of the transducer into the objective focal point. The use of LIPUS is illustrated with an example of LIPUS-induced calcium transients in cultured human glioblastoma cells measured using calcium imaging.

Low-Intensity Pulsed Ultrasound Stimulation (LIPUS) is a modality for non-invasive mechanical stimulation of endogenous or engineered cells with high spatial and temporal resolution. This article describes how to implement LIPUS to an epi-fluorescence microscope and how to minimize acoustic impedance mismatch along the ultrasound path to prevent unwanted mechanical artefacts.

By focusing low-intensity ultrasound pulses that penetrate soft tissues, LIPUS represents a promising biomedical technology to remotely and safely ...

Measuring the Interaction Force Between a Droplet and a Super-hydrophobic Substrate by the Optical Lever Method

The goal of this paper is to investigate the interaction force between droplets and super-hydrophobic substrates in the air. A measurement system based on an optical lever method is designed. A millimetric cantilever is used as a force sensitive component in the measurement system. Firstly, the force sensitivity of the optical lever is calibrated using electrostatic force, which is the critical step in measuring interaction force. Secondly, three super-hydrophobic substrates with different grid fractions are prepared with nanoparticles and copper grids. Finally, the interaction forces between droplets and super-hydrophobic substrates with different grid fractions are measured by the system. This method can be used to measure the force on the scale of sub-micronewton with a resolution on the scale of nanonewton. The in-depth study of the contact process of droplets and super-hydrophobic structures can help to improve the production efficiency in coating, film and printing. The force measurement system designed in this paper can also be used in other fields of microforce measurement.

The protocol aims to investigate the interaction between droplets and super-hydrophobic substrates in the air. This includes calibrating the measurement system and measuring the interaction force at super-hydrophobic substrates with different grid fractions.

The goal of this paper is to investigate the interaction force between droplets and super-hydrophobic substrates in the air. A measurement system based on ...

Recording Ultra-Realistic Full-Color Analog Holograms for Use in a Moving Hologram Display

This paper demonstrates a method to record a set of twelve ultra-realistic full-color analog holograms presenting the same brightness, transparency and homogeneous colors for the fabrication of a Fantatrope, a dynamic holographic 3D display, without the need for special viewing aids. The method involves the use of 3D printer technology, a single-beam full-color Denisyuk optical setup with three low-power lasers (red, green, and blue) and an iso-panchromatic high-sensitive silver-halide holographic emulsion specially designed for recording analog holograms without any diffusion. A cyclic animation is created with a 3D computer graphics program and different elements are 3D printed to form models for the holograms. Holograms are recorded with a full-color holographic setup and developed using two simple chemical baths. To prevent any emulsion thickness variations, the holograms are sealed with optical glue. Results confirm that all holograms recorded with this protocol present the same characteristics, which allow them to be used in the Fantatrope.

We present a protocol to record a set of ultra-realistic full-color analog holograms, showing the same brightness, transparency, and homogeneous colors, on ultra-fine-grain silver-halide holographic emulsions for the fabrication of a dynamic holographic 3D display.

This paper demonstrates a method to record a set of twelve ultra-realistic full-color analog holograms presenting the same brightness, transparency and ...