An integrated method based on optical and digital image processing is presented to suppress speckle in digital holography. A spatial light modulator is adopted to introduce random phases to the illuminating beam. Mult...An integrated method based on optical and digital image processing is presented to suppress speckle in digital holography. A spatial light modulator is adopted to introduce random phases to the illuminating beam. Multiple holograms are reconstructed and superimposed, and the intensity is averaged to smooth the noise. The adaptive algorithm based on the nonlocal means is designed to further suppress the speckle. The presented method is compared with other methods reduction is improved, and the proposed method is effective The experimental results show that speckle and feasible.展开更多
A lensless Vanderlugt optical correlator using two phase-only spatial light modulators （SLMs） is proposed. The SLMs are used for displaying input and filter patterns respectively. The SLMs are also used as programma...A lensless Vanderlugt optical correlator using two phase-only spatial light modulators （SLMs） is proposed. The SLMs are used for displaying input and filter patterns respectively. The SLMs are also used as programmable lenses in order to realize the lensless construction. This lensless system is simple and its alignment adjustment is easy. The performance of the SLMs as programmable lenses is also described.展开更多
Multi-beam ultra-fast laser parallel microprocessing using spatial light modulation is demonstrated in this paper.Diffractive multi-beam patterns are generated with a spatial light modulator(SLM),which is driven by co...Multi-beam ultra-fast laser parallel microprocessing using spatial light modulation is demonstrated in this paper.Diffractive multi-beam patterns are generated with a spatial light modulator(SLM),which is driven by computer generated holograms(CGHs).The CGHs calculated by appropriate algorithms are displayed on the SLM to split an input laser beam to a number of beamlets and digitally manipulate their positions and intensity.The undesired damage by the energetic zero order beam can be avoided by either installing a 4f optical system to block the zero order at the Fourier plane or adding a Fresnel zone lens on the CGH to defocus the zero order at the processing plane.The surface ablation of materials using multi-beam patterns synchronised with a scanning galvanometer system shows flexible and high throughput parallel processing.By tightly focusing the diffractive beams with an objective into transparent materials,high speed dynamic femto-second laser two-dimensional(2D) and three-dimensional(3D) internal structuring is also presented.The results demonstrate the high precision micro-processing with higher efficiency,showing the potential for ultra-fast laser parallel processing in real industrial applications.展开更多
Multiple quantum well spatial light modulators with 128×128 array in 38μm pitch are fabricated using two pproaches, one with an attachment of an optical substrate and another one without. These two fabrication p...Multiple quantum well spatial light modulators with 128×128 array in 38μm pitch are fabricated using two pproaches, one with an attachment of an optical substrate and another one without. These two fabrication processes are described and compared.展开更多
The phase modulation characteristics of a reflective liquid crystal （LC） spatial light modulator （SLM） under oblique incidence are studied by using our proposed self-interference method. The experimental setup of ...The phase modulation characteristics of a reflective liquid crystal （LC） spatial light modulator （SLM） under oblique incidence are studied by using our proposed self-interference method. The experimental setup of the method is very simple and has good robustness to mechanical vibrations. By changing the gray value of the combined grayscale loaded on the LC-SLM, different sheared fringe patterns, generated by the interference between the constant phase-modulated beam and the ＋1-order diffracted beam of the blazed grating, can be obtained. The amount of phase modulation of the LC-SLM is obtained by subtracting the phase of the two side lobes in the frequency domain. By turning the turntable where the SLM is mounted, the phase modulation characteristics at different incident angles can be measured. The experimental results show that the phase modulation curves do not change significantly with the small angle. When the angle is large （i.e. larger than 10°）, the phase modulation curves become different, especially for the high gray levels. With the increase of the incident angle, the phase modulation depth is reduced. The results indicate that the incident angle plays an important role in the performance of the phase modulation of an LC-SLM.展开更多
基金supported by the National Natural Science Foundation of China(No.61177018)the Program for New Century Excellent Talents in University(No.NECT-11-0596)+1 种基金the Key Program of Beijing Sci-ence and Technology Plan(No.D121100004812001)Beijing Nova Program(No.2011066)
文摘An integrated method based on optical and digital image processing is presented to suppress speckle in digital holography. A spatial light modulator is adopted to introduce random phases to the illuminating beam. Multiple holograms are reconstructed and superimposed, and the intensity is averaged to smooth the noise. The adaptive algorithm based on the nonlocal means is designed to further suppress the speckle. The presented method is compared with other methods reduction is improved, and the proposed method is effective The experimental results show that speckle and feasible.
文摘A lensless Vanderlugt optical correlator using two phase-only spatial light modulators （SLMs） is proposed. The SLMs are used for displaying input and filter patterns respectively. The SLMs are also used as programmable lenses in order to realize the lensless construction. This lensless system is simple and its alignment adjustment is easy. The performance of the SLMs as programmable lenses is also described.
文摘Multi-beam ultra-fast laser parallel microprocessing using spatial light modulation is demonstrated in this paper.Diffractive multi-beam patterns are generated with a spatial light modulator(SLM),which is driven by computer generated holograms(CGHs).The CGHs calculated by appropriate algorithms are displayed on the SLM to split an input laser beam to a number of beamlets and digitally manipulate their positions and intensity.The undesired damage by the energetic zero order beam can be avoided by either installing a 4f optical system to block the zero order at the Fourier plane or adding a Fresnel zone lens on the CGH to defocus the zero order at the processing plane.The surface ablation of materials using multi-beam patterns synchronised with a scanning galvanometer system shows flexible and high throughput parallel processing.By tightly focusing the diffractive beams with an objective into transparent materials,high speed dynamic femto-second laser two-dimensional(2D) and three-dimensional(3D) internal structuring is also presented.The results demonstrate the high precision micro-processing with higher efficiency,showing the potential for ultra-fast laser parallel processing in real industrial applications.
文摘Multiple quantum well spatial light modulators with 128×128 array in 38μm pitch are fabricated using two pproaches, one with an attachment of an optical substrate and another one without. These two fabrication processes are described and compared.
基金financially supported by the National Natural Science Foundation of China(No.51705404)the China Postdoctoral Science Foundation(No.2016M602806)the Fundamental Research Funds for the Central Universities(No.xjj2017093)
文摘The phase modulation characteristics of a reflective liquid crystal （LC） spatial light modulator （SLM） under oblique incidence are studied by using our proposed self-interference method. The experimental setup of the method is very simple and has good robustness to mechanical vibrations. By changing the gray value of the combined grayscale loaded on the LC-SLM, different sheared fringe patterns, generated by the interference between the constant phase-modulated beam and the ＋1-order diffracted beam of the blazed grating, can be obtained. The amount of phase modulation of the LC-SLM is obtained by subtracting the phase of the two side lobes in the frequency domain. By turning the turntable where the SLM is mounted, the phase modulation characteristics at different incident angles can be measured. The experimental results show that the phase modulation curves do not change significantly with the small angle. When the angle is large （i.e. larger than 10°）, the phase modulation curves become different, especially for the high gray levels. With the increase of the incident angle, the phase modulation depth is reduced. The results indicate that the incident angle plays an important role in the performance of the phase modulation of an LC-SLM.
