Flexible contrast for low-coherence interference microscopy by Fourier-plane filtering with a spatial light modulator

Author(s): Stefan E. Schausberger, Bettina Heise, Christian Maurer, Stefan Bernet, Monika Ritsch-Marte, and David Stifter

Abstract:

“We propose a full-field low-coherence interference (LCI) microscope that can provide different contrast modes using Fourier-plane filtering by means of a spatial light modulator. By altering the phase and spatial frequencies of the backreflected wavefront from the sample arm of the interferometer, we are able to change the contrast in the depth-resolved LCI images. We demonstrate that different types of contrast modes, such as, e.g., spiral phase contrast, can successfully be emulated to provide specific enhancement of internal structures and edges and to reveal complementary details within the samples under investigation.”

Link to Publications Page

Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 35, Issue 24, pp. 4154-4156 (2010)
DOI: 10.1364/OL.35.004154

Dynamic space shaping of intense ultrashort laser light with blazed-type gratings

Author(s): I. Marienko, V. Denisenko, V Slusar, and M. Soskin

Abstract:

“A beam shaper for dynamic transversal shaping of broadband laser pulses that utilizes a blazed ruled grating and a blazed-type grating simulated on Spatial Light Modulator was demonstrated. The introduced shaper scheme is an extension of 2f-2f scheme [Mariyenko, et al., Opt. Express 13, 7599 (2005)] where the two thin holograms with matched grating constants performed light shaping. The new scheme utilizes the diffraction gratings with different grating constants. Dispersion-free light shaping is achieved by means of the intermediate transversal light beam magnification. The magnification balances the mismatch in the grating constants resulting in total residual angular dispersion compensation. In turn, the magnified beam covers a greater area on the modulator matrix thus reducing the incident light power density by a value equal to square of the magnification factor. It translates to the safe-operation threshold extension of the modulator allowing shaping pulses that are powerful enough to be used in the applications. With a proper components selection, the throughput efficiency of the shaper can be well above 40%. A proper shaper operation was demonstrated with the 140-fs Ti:Sapphire oscillator. Theoretical calculations support the conclusions.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 18, Issue 24, pp. 25143-25150 (2010)
DOI: 10.1364/OE.18.025143

Generation of a high depth of focus with constant transversal spot size using a phase-only pupil filter

Author(s): D. Iwaniuk, E. Hack, P. Rastogi.

Abstract:

“A novel approach is proposed to obtain an extended depth of focus (DoF) in white light with constant transversal spot size within the DoF. It combines a phase-only pupil filter based on multiplexed radial zones with alternating quartic phase functions. The design is first tested via numerical simulations of the point spread function (PSF) based on the scalar diffraction theory. The results for a fourfold gain of the depth of focus are experimentally verified with a phase-only spatial light modulator liquid crystal device combined with a 3D PSF measurement system. A close conformity between the experimental and simulation results proves the effectiveness of the proposed approach.”

Link to Publications Page

Publication: Journal of Modern Optics
Issue/Year: Journal of Modern Optics, Volume 57, Issue 21, (2010)
DOI: 10.1080/09500340.2010.529516

Isotropic Diffraction-Limited Focusing Using a Single Objective Lens

Author(s): Emeric Mudry, Eric Le Moal, Patrick Ferrand, Patrick C. Chaumet, and Anne Sentenac

Abstract:

“Focusing a light beam through a lens produces an anisotropic spot elongated along the optical axis, because the light comes from only one side of the focal point. Using the time-reversal concept, we show that isotropic focusing can be realized by placing a mirror after the focal point and shaping the incident beam. This idea is applied to confocal microscopy and brings about a dramatic improvement of the axial resolution.”

Link to Publications Page

Publication: Physical Review Letters
Issue/Year: Phys. Rev. Lett., Volume 105, 203903 (2010)
DOI: 10.1103/PhysRevLett.105.203903

Optimal noise suppression in Fresnel incoherent correlation holography (FINCH) configured for maximum imaging resolution

Author(s): Barak Katz, Dov Wulich, and Joseph Rosen

Abstract:

“An optimal setup in the sense of imaging resolution for the Fresnel incoherent correlation holography (FINCH) system is proposed and analyzed. Experimental results of the proposed setup in reflection mode suffer from low signal-to-noise ratio (SNR) due to a granular noise. SNR improvement is achieved by two methods that rely on increasing the initial amount of phase-shifted recorded holograms. In the first method, we average over several independent complex-valued digital holograms obtained by recording different sets of three digital phase-shifted holograms. In the second method, the least-squares solution for solving a system of an overdetermined set of linear equations is approximated by utilizing the Moore–Penrose pseudoinverse. These methods improve the resolution of the reconstructed image due to their ability to reveal fine and weak details of the observed object.”

Link to Publications Page

Publication: Applied Optics
Issue/Year: Applied Optics, Vol. 49, Issue 30, pp. 5757-5763 (2010)
DOI: 10.1364/AO.49.005757

Combination of scene-based and stochastic measurement for wide-field aberration correction in microscopic imaging

Author(s):

Michael Warber, Selim Maier, Tobias Haist, and Wolfgang Osten

Abstract:

“We report on a novel aberration correction technique that uses the sequential combination of two different aberration measurement methods to correct for setup-induced and specimen-induced aberrations. The advantages of both methods are combined and, thus, the measurement time is strongly reduced without loss of accuracy. The technique is implemented using a spatial-light-modulator-based wide-field microscope without the need for additional components (e.g., a Shack–Hartmann sensor). The aberrations are measured without a reference object by directly using the specimen to be imaged. We demonstrate experimental results for technical as well as biological specimens.”

Link to Publications Page

Publication: Applied Optics
Issue/Year: Vol. 49, Issue 28, pp. 5474-5479 (2010)
DOI: 10.1364/AO.49.005474

Increasing multimode fiber transmission capacity by mode selective spatial light phase modulation

Author(s): Stepniak, G.; Maksymiuk, L.; Siuzdak, J.;

Abstract:

“We propose spatial light modulation with binary phase filters to increase the transmission bandwidth of multimode fibers. In the experiment more than 300 % of bandwidth enhancement is obtained.”

Link to Publications Page

Publication: ECOC Proceedings
Issue/Year: 36th European Conference and Exhibition on Optical Communication (ECOC), 2010
DOI: 10.1109/ECOC.2010.5621465

A SAR multilook optronic processor for operational Earth monitoring applications

Author(s): Linda Marchese, Pascal Bourqui, Sandra Turgeon, Michel Doucet, Carl Vachon, François Châteauneuf, Alain Bergeron, Bernd Harnisch and Martin Suess.

Abstract:

“Synthetic Aperture Radar (SAR) is the only remote sensing technology that can provide high resolution images in adverse weather conditions and in day or night times. It is thus is a powerful tool for Earth monitoring. Certain applications, such as disaster relief, military reconnaissance and ice-flow and ship monitoring require a continuous flow of high-resolution images covering large areas; however, given the large amount of complex data generated and system limitations of data bandwidth and processing speed, not all the requirements can be met at the same time. In addition, multiple user requests are often submitted to the SAR system platform, and not all can be addressed, again due to limitations of area coverage. Increasing the speed of SAR processors and processing on-board are two ways to improve the SAR data throughput and therefore to meet the operational needs of all users. This paper discusses an optronic SAR processor capable of rapidly processing full-scene multi-looked images. Details of the processor design and image results are discussed. Estimations for speed and image throughput are provided, all presented in the context of the requirements for operational service of the various applications.”

Link to Publications Page

Publication: SPIE Proceedings
Issue/Year:Proc. SPIE, Volume 7829, 782904 (2010)
DOI: 10.1117/12.866986

Imaging through turbid layers by scanning the phase conjugated second harmonic radiation from a nanoparticle

Author(s): Chia-Lung Hsieh, Ye Pu, Rachel Grange, Grégoire Laporte, Demetri Psaltis

Abstract:

“We demonstrate imaging through a turbid layer by using digital phase conjugation of the second harmonic field radiated from a beacon nanoparticle. We show that the phase-conjugated focus can be displaced from its initial position by illuminating the same region of the turbid layer with an angular offset. An image is obtained by scanning the phase-conjugated focus through the turbid layer in a region around the nanoparticle. We obtain a clear image of the target by measuring the light transmitted through it when scanning the focused beam.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 18, Issue 20, pp. 20723-20731 (2010)
DOI: 10.1364/OE.18.020723

Rapid calculation algorithm of Fresnel computer-generated-hologram using look-up table and wavefront-recording plane methods for three-dimensional display

Author(s): Tomoyoshi Shimobaba, Hirotaka Nakayama, Nobuyuki Masuda, and Tomoyoshi Ito

Abstract:

“A rapid calculation method of Fresnel computer-generatedhologram (CGH) using look-up table and wavefront-recording plane (WRP) methods toward three-dimensional (3D) display is presented. The method consists of two steps: the first step is the calculation of a WRP that is placed between a 3D object and a CGH. In the second step, we obtain an amplitude-type or phase-type CGH to execute diffraction calculation from the WRP to the CGH. The first step of the previous WRP method was difficult to calculate in real-time due to the calculation cost. In this paper, in order to obtain greater acceleration, we apply a look-up table method to the first step. In addition, we use a graphics processing unit in the second step. The total computational complexity is dramatically reduced in comparison with conventional CGH calculations. We show optical reconstructions from a 2,048×2,048 phase-type CGH generated by about 3×104 object points over 10 frames per second.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 18, Issue 19, pp. 19504-19509 (2010)
DOI: 10.1364/OE.18.019504
1 2 3 4