Application of cooled spatial light modulator for high power nanosecond laser micromachining

Author(s): Rainer J. Beck, Jonathan P. Parry, William N. MacPherson, Andrew Waddie, Nick J. Weston, Jonathan D. Shephard, and Duncan P. Hand

Abstract:

“The application of a commercially available spatial light modulator (SLM) to control the spatial intensity distribution of a nanosecond pulsed laser for micromachining is described for the first time. Heat sinking is introduced to increase the average power handling capabilities of the SLM beyond recommended limits by the manufacturer. Complex intensity patterns are generated, using the Inverse Fourier Transform Algorithm, and example laser machining is demonstrated. The SLM enables both complex beam shaping and also beam steering.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 18, Issue 16, pp. 17059-17065 (2010)
DOI: 10.1364/OE.18.017059

Optical encryption based on computational ghost imaging

Author(s): Pere Clemente, Vicente Durán, Víctor Torres-Company, Enrique Tajahuerce, Jesús Lancis

Abstract:

“Ghost imaging is an optical technique in which the information of an object is encoded in the correlation of the intensity fluctuations of light. The computational version of this fascinating phenomenon emulates, offline, the optical propagation through the reference arm, enabling 3D visualization of a complex object whose transmitted light is measured by a bucket detector. In this Letter, we show how computational ghost imaging can be used to encrypt and transmit object information to a remote party. Important features, such as key compressibility and vulnerability to eavesdropping, are experimentally analyzed.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 35, Issue 14, pp. 2391-2393 (2010)
DOI: 10.1364/OL.35.002391

Image Transmission Through an Opaque Material

Author(s): S. M. Popoff, G. Lerosey, M. Fink, A.C. Boccara, S. Gigan

Abstract:

“Optical imaging relies on the ability to illuminate an object and to collect and make sense of the light it scatters or transmit. Propagation through complex media such as biological tissues was so far believed to degrade the attainable depth as well as the resolution for imaging cite{sebbah2001introduction} because of multiple scattering. This is why such media are usually considered opaque. Recent experiments have demonstrated that multiply scattered light can in fact be harnessed thanks to wavefront control, and even put to profit to surpass what one can achieve within a homogenous medium in terms of focusing. Very recently, we have proven that it is possible to measure the complex mesoscopic optical transmission channels that allow light to traverse through an opaque medium. Here we show that we can optimally exploit those channels to coherently transmit and recover with a high fidelity an arbitrary image, independently of the complexity of the propagation. Our approach gives a general framework for coherent imaging in complex media, going well beyond focusing. It is valid for any linear complex media, and could be extended to several novel photonic materials, whatever the amount of scattering or disorder (from complete disorder to weakly disordered photonic crystals, and from superdiffusive to Anderson localization). ”

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Publication:arXiv.org / physics
Issue/Year:arXiv:1005.0532 (May 2010)

Measuring the Transmission Matrix in Optics: An Approach to the Study and Control of Light Propagation in Disordered Media

Author(s): S. M. Popoff, G. Lerosey, R. Carminati, M. Fink, A. C. Boccara, S. Gigan

Abstract:

“We introduce a method to experimentally measure the monochromatic transmission matrix of a complex medium in optics. This method is based on a spatial phase modulator together with a full-field interferometric measurement on a camera. We determine the transmission matrix of a thick random scattering sample. We show that this matrix exhibits statistical properties in good agreement with random matrix theory and allows light focusing and imaging through the random medium. This method might give important insight into the mesoscopic properties of a complex medium.”

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Publication: Physical Review Letters
Issue/Year: Phys. Rev. Lett., Volume 104, Issue 10, 100601 (2010)
DOI: 10.1103/PhysRevLett.104.100601

Self-reference quantitative phase microscopy for microfluidic devices

Author(s): Jaeduck Jang, Chae Yun Bae, Je-Kyun Park, Jong Chul Ye

Abstract:

“This Letter describes a quantitative phase microscopy for microfluidic devices using a simple self-referencing interferometry. Compared with the gross dimensions of the microfluidic device, the microchannel occupies only a small area of the device. Hence, the reference field can be generated by inverting the relative position of the specimen and background. Our system is realized using an extended depth-of-field optics in the form of Michelson interferometry, which allows quantitative phase measurement for an increased depth-of-field without moving objective lens or specimen. Furthermore, the system can be readily converted to a higher signal-to-noise ratio Hilbert phase microscopy thanks to the simultaneous acquisition of double interferograms. The performance of our system is verified using polymer beads, micropatterning poly(dimethylsiloxane) (PDMS), and embryo cells in the microchannels.”

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Publication:Optics Letters
Issue/Year: Optics Letters, Vol. 35, Issue 4, pp. 514-516 (2010)
DOI: 10.1364/OL.35.000514

Implementation of a digital optical phase conjugation system and its application to study the robustness of turbidity suppression by phase conjugation

Author(s): Meng Cui, Changhuei Yang

Abstract:

“In this work, we report a novel high capacity (number of degrees of freedom) open loop adaptive optics method, termed digital optical phase conjugation (DOPC), which provides a robust optoelectronic optical phase conjugation (OPC) solution. We showed that our prototype can phase conjugate light fields with ~3.9 x 10−3 degree accuracy over a range of ~3 degrees and can phase conjugate an input field through a relatively thick turbid medium (μsl ~13). Furthermore, we employed this system to show that the reversing of random scattering in turbid media by phase conjugation is surprisingly robust and accommodating of phase errors. An OPC wavefront with significant spatial phase errors (error uniformly distributed from – π/2 to π/2) can nevertheless allow OPC reconstruction through a scattering medium with ~40% of the efficiency achieved with phase error free OPC.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 18, Issue 4, pp. 3444-3455 (2010)
DOI: 10.1364/OE.18.003444

Self-reference extended depth-of-field quantitative phase microscopy

Author(s): Jaeduck Jang, Chae Yun Bae, Je-Kyun Park, and Jong Chul Ye

Abstract:

“This paper describes a novel quantitative phase microscopy based on a simple self-referencing scheme using Michelson interferometry. In order to achieve the homogeneous reference field for accurate phase measurement, the imaging field-of-view (FOV) is split onto the sample and homogenous background areas. The reference field can be generated by rotating the relative position of the sample and homogenous background in the object arm. Furthermore, our system is realized using an extended depth-of-field (eDOF) optics, which allows quantitative phase measurement for an increase of the depth-of-field without moving objective lens or specimen. The proposed method is confirmed by experimental results using various samples such as polystyrene beads and red blood cells (RBCs).”

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Publication: SPIE Proceedings
Issue/Year: Proc. SPIE 7570, 757018 (2010)
DOI: 10.1117/12.843082

Individually controlled multi-focus laser processing for two-photon polymerization

Author(s): Kotaro Obata, Jürgen Koch, and Boris N. Chichkov

Abstract:

“A parallel processing of two-photon polymerization structuring is demonstrated with spatial light modulator. Spatial light modulator generates multi-focus spots on the sample surface via phase modulation technique controlled by computer generated hologram pattern. Each focus spot can be individually controlled in position and laser intensity with computer generated hologram pattern displayed on spatial light modulator. The multi-focus spots two-photon polymerization achieves the fabrication of asymmetric structure. Moreover, smooth sine curved polymerized line with amplitude of 5 μm and a period of 200 μm was obtained by fast switching of CGH pattern.”

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Publication: SPIE Proceedings / Volume 7584 / Nonlinear Processing
Issue/Year: Proc. SPIE 7584, 75840L (2010)
DOI: 10.1117/12.842117

Nonspherical laser-induced cavitation bubbles

Author(s): Kang Yuan Lim, Pedro A. Quinto-Su, Evert Klaseboer, Boo Cheong Khoo, Vasan Venugopalan, Claus-Dieter Ohl

Abstract:

“The generation of arbitrarily shaped nonspherical laser-induced cavitation bubbles is demonstrated with a optical technique. The nonspherical bubbles are formed using laser intensity patterns shaped by a spatial light modulator using linear absorption inside a liquid gap with a thickness of 40 μm. In particular we demonstrate the dynamics of elliptic, toroidal, square, and V-shaped bubbles. The bubble dynamics is recorded with a high-speed camera at framing rates of up to 300 000 frames per second. The observed bubble evolution is compared to predictions from an axisymmetric boundary element simulation which provides good qualitative agreement. Interesting dynamic features that are observed in both the experiment and simulation include the inversion of the major and minor axis for elliptical bubbles, the rotation of the shape for square bubbles, and the formation of a unidirectional jet for V-shaped bubbles. Further we demonstrate that specific bubble shapes can either be formed directly through the intensity distribution of a single laser focus, or indirectly using secondary bubbles that either confine the central bubble or coalesce with the main bubble. The former approach provides the ability to generate in principle any complex bubble geometry.”

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Publication: Physical Review E
Issue/Year: Phys. Rev. E, Volume 81, Issue 1, 016308 (2010)
DOI: 10.1103/PhysRevE.81.016308

Diffractive performance of square Fresnel zone plates

Author(s): Javier Alda, José María Rico-García, Francisco Javier Salgado-Remacha, Luis Miguel Sanchez-Brea

Abstract:

“We analyze the optical behavior of square Fresnel zones plates. A theoretical analysis and numerical simulations based on the Rayleigh–Sommerfeld approach have been developed analyzing properties such as the depth of focus and the intensity of the focus in terms of the number of zones. In addition, an experimental verification has been performed using a Spatial Light Modulator to implement the designed square Fresnel zones plates.”

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Publication: Optics Communications
Issue/Year: Optics Communications, Volume 282, Issue 17, 1 September 2009, Pages 3402-3407
DOI: 10.1016/j.optcom.2009.05.053
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