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Akram M.N.,Buskerud and Vestfold University College | Tong Z.,Buskerud and Vestfold University College | Ouyang G.,Buskerud and Vestfold University College | Chen X.,Buskerud and Vestfold University College | Kartashov V.,Polight Inc.
Applied Optics | Year: 2010

We utilize spatial and angular diversityto achieve speckle reduction in laser illumination. Both free-space and imaging geometry configurations are considered. A fast two-dimensional scanning micromirror is employed to steer the laser beam. A simple experimental setup is built to demonstrate the application of our technique in a two-dimensional laser picture projection. Experimental results show that the speckle contrast factor can be reduced down to 5% within the integration time of the detector. © 2010 Optical Society of America. Source


Nadeem Akram M.,Buskerud and Vestfold University College | Kartashov V.,Polight Inc. | Tong Z.,Buskerud and Vestfold University College
Optics Letters | Year: 2010

A Barker binary phase code of maximum length 13 has previously been used for speckle reduction in linescan laser projectors, and a speckle contrast factor decrease down to 13% has been achieved. In this Letter, Barker-like binary phase codes of lengths longer than 13 are used at an intermediate image plane. It is shown by theoretical calculation that a much better speckle reduction with a speckle contrast factor up to 6% can be achieved by using longer binary phase codes other than the Barker code. © 2010 Optical Society of America. Source


Ouyang G.,Buskerud and Vestfold University College | Tong Z.,Buskerud and Vestfold University College | Nadeem Akram M.,Buskerud and Vestfold University College | Wang K.,Buskerud and Vestfold University College | And 3 more authors.
Optics Letters | Year: 2010

Speckle reduction by moving diffuser has been previously studied in display systems with coherent light sources, such as lasers. In this Letter, we propose a motionless diffractive optical element (DOE) for speckle reduction. The DOE was designed based on finite-element method simulations, fabricated using micromachining technology, and characterized for despeckle efficiency. Experiments using a DOE with two gratings have indicated that the speckle was suppressed to 50%, which shows fair agreement with theoretical analysis. With some modification of this DOE, the speckle noise can be reduced to 10% according to the theory. © 2010 Optical Society of America. Source


Ouyang G.,Buskerud and Vestfold University College | Wang K.,Buskerud and Vestfold University College | Akram M.N.,Buskerud and Vestfold University College | Henriksen L.,Polight Inc. | Chen X.Y.,Buskerud and Vestfold University College
Applied Physics A: Materials Science and Processing | Year: 2011

The cross-linked networks of linear vinyl-terminated poly(dimethylsiloxane) (PDMS) with trimethylsiloxy-terminated methyhydrosiloxane-dimethylsiloxane copolymer (cross-linker) were investigated by tuning the cross-linker concentration, the chain length of linear PDMS and the functionality of the cross-linker. Response time and elastic modulus of the cross-linked PDMS elastomer were characterized by home-made measurement systems and analyzed based on their network topologies. An optimized PDMS elastomer, which has response time of 9 μs and elastic modulus of 601 kPa, was utilized as the actuation material in a MEMS spatial light modulator (SLM). The fabrication processes were described. This polymer based SLM has shown fast response time (9 μs) and successfully diffracted light into higher orders with 84% first-order diffraction efficiency. © 2011 Springer-Verlag. Source


Ouyang G.,Buskerud and Vestfold University College | Wang K.,Buskerud and Vestfold University College | Henriksen L.,Polight Inc. | Akram M.N.,Buskerud and Vestfold University College | Chen X.Y.,Buskerud and Vestfold University College
Sensors and Actuators, A: Physical | Year: 2010

A tunable grating using viscoelastic PDMS (polydimethylsiloxane) and conductive polymer PEDOT (poly 3,4-ethylenedioxythiophene): PSS (polystyrenesulfonate) was designed and the fabrication process was developed. A sandwich structure (PEDOT: PSS/PDMS/Gold electrode) was utilized. By applying voltage between the PEDOT: PSS top film and the bottom interdigital gold electrode, the initial plane surface of polymers deforms into a sinusoidal grating. The PDMS material properties were tuned by modifying the network structure to obtain good actuation of the polymer, including large relief depth and fast response speed. The grating profile on the surface was observed with the maximum relief depth of 200 nm. The response time of the modulator can reach 250 μs. © 2010 Elsevier B.V. All rights reserved. Source

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