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Guo H, Tang W, Wang Z, Yuan L, Li Y, He D, Wang Q, Huang Y. Liquid crystal wavefront correction based on improved machine learning for free-space optical communication. APPLIED OPTICS 2023; 62:9470-9475. [PMID: 38108771 DOI: 10.1364/ao.505697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 11/15/2023] [Indexed: 12/19/2023]
Abstract
In order to suppress the impact of atmosphere turbulence on the space laser communication link, the wavefront correction technology of a liquid crystal spatial light modulator (LCSLM) is studied. Combining with the control mode of the LCSLM, we propose an improved deep learning approach that restores the input image features into the wavefront and then controls the LCSLM to compensate for the phase distortion. This method does not have Zernike coefficient truncation and does not require the calculation of coefficient matrices, thus improving the accuracy and efficiency of the algorithm. At the same time, as for its powerful phase fitting ability, the LCSLM can be used as a turbulence simulator to construct datasets. During the training process of the neural networks, a calibration between the LCSLM and deep learning is established. Finally, a spatial optical coupling experimental system is built. The results show that, under different atmospheric conditions, the liquid crystal wavefront correction method has a significant improvement in terminal coupling efficiency and has certain application prospects in the field of free-space optical communication.
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Correction of Distorted Wavefront Using Dual Liquid Crystal Spatial Light Modulators. PHOTONICS 2022. [DOI: 10.3390/photonics9060426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In space optical communication, owing to the influence of atmospheric turbulence, optical beams lose focus and become phase-distorted, which reduces the communication quality. Considering the polarization dependence of liquid crystal spatial light modulators and the dispersion effect of liquid crystal materials, the energy utilization rate of liquid crystal adaptive optics systems is low. In this study, a dual liquid crystal spatial light modulator adaptive optics system based on the GS algorithm is used to correct the wavefront distortion of a signal beam under different atmospheric turbulence intensities, and the Strehl ratio (SR) is used as the evaluation index. The simulation results show that the SR of the corrected system can be increased from 0.23, 0.41, and 0.72 to 0.77, 0.89, and 0.95, respectively. The corrected beam spot was more concentrated and the light intensity at the center of the beam spot was stronger. The experimental results show that, after the distortion wavefront is corrected by the dual liquid crystal spatial light modulator, the average gray value of the 10 × 10 pixels in the center of the spot increases from 159.3, 113.1, and 58.4 to 253.4, 247.7, and 198.3, respectively.
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Saha P, Ansari N, Kitchens CL, Ashurst WR, Davis VA. Microelectromechanical Systems from Aligned Cellulose Nanocrystal Films. ACS APPLIED MATERIALS & INTERFACES 2018; 10:24116-24123. [PMID: 29938487 DOI: 10.1021/acsami.8b04985] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Microelectromechanical systems (MEMS) have become a ubiquitous part of a multitude of industries including transportation, communication, medical, and consumer products. The majority of commercial MEMS devices are produced from silicon using energy-intensive and harsh chemical processing. We report that actuatable standard MEMS devices such as cantilever beam arrays, doubly clamped beams, residual strain testers, and mechanical strength testers can be produced via low-temperature fabrication of shear-aligned cellulose nanocrystal (CNC) films. The devices had feature sizes as small as 6 μm and anisotropic mechanical properties. For 4 μm thick doubly clamped beams with the CNC aligned parallel to the devices' long axes, the Young's moduli averaged 51 GPa and the fracture strength averaged 1.1 GPa. These mechanical properties are within one-third of typical values for polysilicon devices. This new paradigm of producing MEMS devices from CNC extracted from waste biomass provides the simplicity and tunability of fluid-phase processing while enabling anisotropic mechanical properties on the order of those obtained in standard silicon MEMS.
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Affiliation(s)
- Partha Saha
- Department of Chemical Engineering , Auburn University , Auburn , Alabama 36849 , United States
| | - Naveed Ansari
- Department of Chemical Engineering , Auburn University , Auburn , Alabama 36849 , United States
| | - Christopher L Kitchens
- Department of Chemical and Biomolecular Engineering , Clemson University , Clemson , South Carolina 29634 , United States
| | - W Robert Ashurst
- Department of Chemical Engineering , Auburn University , Auburn , Alabama 36849 , United States
| | - Virginia A Davis
- Department of Chemical Engineering , Auburn University , Auburn , Alabama 36849 , United States
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Xu Z, Yang C, Zhang P, Zhang X, Cao Z, Mu Q, Sun Q, Xuan L. Visible light high-resolution imaging system for large aperture telescope by liquid crystal adaptive optics with phase diversity technique. Sci Rep 2017; 7:10034. [PMID: 28855552 PMCID: PMC5577037 DOI: 10.1038/s41598-017-09595-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 07/26/2017] [Indexed: 11/10/2022] Open
Abstract
There are more than eight large aperture telescopes (larger than eight meters) equipped with adaptive optics system in the world until now. Due to the limitations such as the difficulties of increasing actuator number of deformable mirror, most of them work in the infrared waveband. A novel two-step high-resolution optical imaging approach is proposed by applying phase diversity (PD) technique to the open-loop liquid crystal adaptive optics system (LC AOS) for visible light high-resolution adaptive imaging. Considering the traditional PD is not suitable for LC AOS, the novel PD strategy is proposed which can reduce the wavefront estimating error caused by non-modulated light generated by liquid crystal spatial light modulator (LC SLM) and make the residual distortions after open-loop correction to be smaller. Moreover, the LC SLM can introduce any aberration which realizes the free selection of phase diversity. The estimating errors are greatly reduced in both simulations and experiments. The resolution of the reconstructed image is greatly improved on both subjective visual effect and the highest discernible space resolution. Such technique can be widely used in large aperture telescopes for astronomical observations such as terrestrial planets, quasars and also can be used in other applications related to wavefront correction.
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Affiliation(s)
- Zihao Xu
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese academy of Sciences, Changchun, Jilin, 130033, China.,Graduate School of the Chinese Academy of Sciences, Beijing, 100039, China
| | - Chengliang Yang
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese academy of Sciences, Changchun, Jilin, 130033, China
| | - Peiguang Zhang
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese academy of Sciences, Changchun, Jilin, 130033, China
| | - Xingyun Zhang
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese academy of Sciences, Changchun, Jilin, 130033, China
| | - Zhaoliang Cao
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese academy of Sciences, Changchun, Jilin, 130033, China
| | - Quanquan Mu
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese academy of Sciences, Changchun, Jilin, 130033, China.
| | - Qiang Sun
- Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin, 130033, China.
| | - Li Xuan
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese academy of Sciences, Changchun, Jilin, 130033, China
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Zhang X, Cao Z, Xu H, Wang Y, Li D, Wang S, Yang C, Mu Q, Xuan L. High precision system modeling of liquid crystal adaptive optics systems. OPTICS EXPRESS 2017; 25:9926-9937. [PMID: 28468372 DOI: 10.1364/oe.25.009926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this paper, we present a heuristic method to simplify the liquid crystal adaptive optics system (LCAOS) into a single-input-single-output (SISO) system, then build the dynamic model of LCAOS based on subspace identification. Results show that the identified model could accurately describe the dynamical behavior of LCAOS (97% match), with extremely low complexity. The wonderful features of low complexity and high precision, make the identified model highly beneficial for model based controller design, system analysis and dynamical behavior simulation of liquid crystal adaptive optics systems.
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Sun F, Cao Z, Wang Y, Zhang C, Zhang X, Liu Y, Mu Q, Xuan L. DM/LCWFC based adaptive optics system for large aperture telescopes imaging from visible to infrared waveband. OPTICS EXPRESS 2016; 24:27494-27508. [PMID: 27906321 DOI: 10.1364/oe.24.027494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Almost all the deformable mirror (DM) based adaptive optics systems (AOSs) used on large aperture telescopes work at the infrared waveband due to the limitation of the number of actuators. To extend the imaging waveband to the visible, we propose a DM and Liquid crystal wavefront corrector (DM/LCWFC) combination AOS. The LCWFC is used to correct the high frequency aberration corresponding to the visible waveband and the aberrations of the infrared are corrected by the DM. The calculated results show that, to a 10 m telescope, DM/LCWFC AOS which contains a 1538 actuators DM and a 404 × 404 pixels LCWFC is equivalent to a DM based AOS with 4057 actuators. It indicates that the DM/LCWFC AOS is possible to work from visible to infrared for larger aperture telescopes. The simulations and laboratory experiment are performed for a 2 m telescope. The experimental results show that, after correction, near diffraction limited resolution USAF target images are obtained at the wavebands of 0.7-0.9 μm, 0.9-1.5 μm and 1.5-1.7 μm respectively. Therefore, the DM/LCWFC AOS may be used to extend imaging waveband of larger aperture telescope to the visible. It is very appropriate for the observation of spatial objects and the scientific research in astronomy.
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Zhang X, Hu L, Cao Z, Mu Q, Li D, Xuan L. Improve the accuracy of interaction matrix measurement for liquid-crystal adaptive optics systems. OPTICS EXPRESS 2014; 22:14221-14228. [PMID: 24977519 DOI: 10.1364/oe.22.014221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present a novel method to measure the interaction matrix of liquid-crystal adaptive optics systems, by applying least squares method to mitigate the impact of measurement noise. Experimental results showed a dramatic gain in the accuracy of interaction matrix, and a considerable improvement in image resolution with open loop adaptive optics correction.
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Liu C, Hu L, Mu Q, Cao Z, Xuan L. Open-loop control of liquid-crystal spatial light modulators for vertical atmospheric turbulence wavefront correction. APPLIED OPTICS 2011; 50:82-89. [PMID: 21221164 DOI: 10.1364/ao.50.000082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present an open-loop adaptive optics (AO) system based on two liquid-crystal spatial light modulators (LCSLMs) that profit from high precision wavefront generation and good repeatability. A wide optical bandwidth of 300 nm is designed for the system, and a new open-loop optical layout is invented to conveniently switch between the open and closed loop. The corresponding control algorithm is introduced with a loop frequency (the reciprocal of the total time delay of a correction loop) of 103 Hz. The system was mounted onto a 2.16 m telescope for vertical atmospheric turbulence correction. The full width at half-maximum of the image of the star α Boo reached 0.636 arc sec after the open-loop correction, while it was 2.12 arc sec before the correction. The result indicates that the open-loop AO system based on LCSLMs potentially has the ability to be used for general astronomical applications.
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Affiliation(s)
- Chao Liu
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin 130033, China
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Li C, Xia M, Li D, Mu Q, Xuan L. High-resolution retinal imaging through open-loop adaptive optics. JOURNAL OF BIOMEDICAL OPTICS 2010; 15:046009. [PMID: 20799811 DOI: 10.1117/1.3466581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Using the liquid crystal spatial light modulator (LC-SLM) as the wavefront corrector, an open-loop adaptive optics (AO) system for fundus imaging in vivo is constructed. Compared with the LC-SLM closed-loop AO system, the light energy efficiency is increased by a factor of 2, which is helpful for the safety of fundus illumination in vivo. In our experiment, the subjective accommodation method is used to precorrect the defocus aberration, and three subjects with different myopia 0, -3, and -5 D are tested. Although the residual wavefront error after correction cannot to detected, the fundus images adequately demonstrate that the imaging system reaches the resolution of a single photoreceptor cell through the open-loop correction. Without dilating and cyclopleging the eye, the continuous imaging for 8 s is recorded for one of the subjects.
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Affiliation(s)
- Chao Li
- State Key Lab of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Changchun, Jilin, China.
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Cao Z, Mu Q, Hu L, Lu X, Xuan L. A simple method for evaluating the wavefront compensation error of diffractive liquid-crystal wavefront correctors. OPTICS EXPRESS 2009; 17:17715-17722. [PMID: 19907557 DOI: 10.1364/oe.17.017715] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A simple method for evaluating the wavefront compensation error of diffractive liquid-crystal wavefront correctors (DLCWFCs) for atmospheric turbulence correction is reported. A simple formula which describes the relationship between pixel number, DLCWFC aperture, quantization level, and atmospheric coherence length was derived based on the calculated atmospheric turbulence wavefronts using Kolmogorov atmospheric turbulence theory. It was found that the pixel number across the DLCWFC aperture is a linear function of the telescope aperture and the quantization level, and it is an exponential function of the atmosphere coherence length. These results are useful for people using DLCWFCs in atmospheric turbulence correction for large-aperture telescopes.
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Affiliation(s)
- Zhaoliang Cao
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin, 130033, China
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Fernández EJ, Prieto PM, Artal P. Wave-aberration control with a liquid crystal on silicon (LCOS) spatial phase modulator. OPTICS EXPRESS 2009; 17:11013-25. [PMID: 19550501 DOI: 10.1364/oe.17.011013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Liquid crystal on Silicon (LCOS) spatial phase modulators offer enhanced possibilities for adaptive optics applications in terms of response velocity and fidelity. Unlike deformable mirrors, they present a capability for reproducing discontinuous phase profiles. This ability also allows an increase in the effective stroke of the device by means of phase wrapping. The latter is only limited by the diffraction related effects that become noticeable as the number of phase cycles increase. In this work we estimated the ranges of generation of the Zernike polynomials as a means for characterizing the performance of the device. Sets of images systematically degraded with the different Zernike polynomials generated using a LCOS phase modulator have been recorded and compared with their theoretical digital counterparts. For each Zernike mode, we have found that image degradation reaches a limit for a certain coefficient value; further increase in the aberration amount has no additional effect in image quality. This behavior is attributed to the intensification of the 0-order diffraction. These results have allowed determining the usable limits of the phase modulator virtually free from diffraction artifacts. The results are particularly important for visual simulation and ophthalmic testing applications, although they are equally interesting for any adaptive optics application with liquid crystal based devices.
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Affiliation(s)
- Enrique J Fernández
- Centro de Investigación en Optica y Nanofísica, Universidad de Murcia, Campus de Espinardo, Murcia, Spain.
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12
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Li C, Xia M, Mu Q, Jiang B, Xuan L, Cao Z. High-precision open-loop adaptive optics system based on LC-SLM. OPTICS EXPRESS 2009; 17:10774-10781. [PMID: 19550476 DOI: 10.1364/oe.17.010774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Used as a wavefront corrector, a liquid crystal spatial modulator (LC-SLM) has good repeatability and linearity, which are essential for open-loop adaptive optics, and the open-loop optical system can increase the light energy efficiency by a factor of two for the LC-SLM and improve the system bandwidth. In order to test the performance of the LC-SLM in open-loop correction, an indoor closed-loop configuration optical system is constructed on the open-loop control method. With this method, it is demonstrated that the residual error after open-loop correction could be smaller than 0.08lambda (RMS: root mean square value) if the initial wavefront aberration is below 2.5lambda (RMS), and the repeatability error of open-loop correction is smaller than 0.01lambda (RMS).
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Affiliation(s)
- Chao Li
- State Key Lab of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin, China
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13
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Park JH, Garipov GK, Jeon JA, Khrenov BA, Kim JE, Kim M, Kim YK, Lee CH, Lee J, Na GW, Nam S, Park IH, Park YS. Obscura telescope with a MEMS micromirror array for space observation of transient luminous phenomena or fast-moving objects. OPTICS EXPRESS 2008; 16:20249-20257. [PMID: 19065163 DOI: 10.1364/oe.16.020249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We introduce a novel telescope consisting of a pinhole-like camera with rotatable MEMS micromirrors substituting for pinholes. The design is ideal for observations of transient luminous phenomena or fast-moving objects, such as upper atmospheric lightning and bright gamma ray bursts. The advantage of the MEMS "obscura telescope" over conventional cameras is that it is capable both of searching for events over a wide field of view, and fast zooming to allow detailed investigation of the structure of events. It is also able to track the triggering object to investigate its space-time development, and to center the interesting portion of the image on the photodetector array. We present the proposed system and the test results for the MEMS obscura telescope which has a field of view of 11.3 degrees, sixteen times zoom-in and tracking within 1 ms.
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Affiliation(s)
- J H Park
- Research Center of MEMS Space Telescope and Department of Physics, Ewha Womans University, 11-1 Daehyun-dong, Seoul 120-750, Korea
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14
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Cao Z, Mu Q, Hu L, Li D, Liu Y, Jin L, Xuan L. Correction of horizontal turbulence with nematic liquid crystal wavefront corrector. OPTICS EXPRESS 2008; 16:7006-7013. [PMID: 18545404 DOI: 10.1364/oe.16.007006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
To correct horizontal turbulences, a nematic liquid crystal wavefront corrector (NLC WFC) with a fast response is used. It can linearly modulate 2pi radian at a wavelength of 633 nm. The closed-loop frequency of the adaptive optics system was originally only 12 Hz. Hence, a control system using the NLC WFC was developed, graphic processing units (GPUs) were used to compute the compensated wavefront, and the driving software for the NLC WFC was optimized. With these improvements, the closed loop frequency increased up to 60 Hz. Finally, the correction of a 500-m horizontal turbulence was performed with this fast adaptive system. After the correction, the averaged peak-to-valley (PV) and root-mean-square (RMS) values of the wavefront were reduced to 0.2 lambda and 0.06 lambda, respectively. The core of a fiber bundle is also resolved with a field angle of 0.68". As the limit of the angular resolution of the telescope is 0.65", the quasi-diffraction limited image is acquired with the closed-loop correction. It is shown that the NLC WFC has the ability to correct weak turbulences.
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Affiliation(s)
- Zhaoliang Cao
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin, China
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Cao Z, Mu Q, Hu L, Liu Y, Peng Z, Xuan L. Reflective liquid crystal wavefront corrector used with tilt incidence. APPLIED OPTICS 2008; 47:1785-1789. [PMID: 18404176 DOI: 10.1364/ao.47.001785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
To allow angular separation of the beam reflected off a liquid crystal wavefront corrector from the incident beam, it is convenient to introduce a small incident angle. This avoids using a beam splitter and the associated energy losses. The effect of the tilt incidence on the liquid crystal wavefront corrector was investigated in this paper. For a parallel aligned liquid crystal wavefront corrector, a simplified model was established and used to analyze the change of the phase modulation under the tilt incidence. The simulated results showed that the effect of the tilt incidence on the phase modulation can be ignored when the angle of tilt incidence is less than 6 degrees. The phase modulation related to the incident angle was measured and the changing trend was similar to the calculated results. The effect of the tilt incidence on the diffraction efficiency of the liquid crystal wavefront corrector was also discussed. The simulated results indicated that the reduction of the diffraction efficiency is less than 1% for incidence angles under 3 degrees. Last, a closed loop correction experiment was done with an incident angle of 1 degrees. After correction, the averaged peak to valley (PV) and root mean square (RMS) of the wavefront were down to 0.15 lambda and 0.03 lambda, respectively, and a resolvable image was acquired.
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Affiliation(s)
- Zhaoliang Cao
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin, 130033, China
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Kam Z, Kner P, Agard D, Sedat JW. Modelling the application of adaptive optics to wide-field microscope live imaging. J Microsc 2007; 226:33-42. [PMID: 17381707 DOI: 10.1111/j.1365-2818.2007.01751.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Wide-field fluorescence microscopy is an essential tool in modern cell biology. Unfortunately the image quality of fluorescence microscopes is often significantly degraded due to aberrations that occur under normal imaging conditions. In this article, we examine the use of adaptive optics technology to dynamically correct these problems to achieve close to ideal diffraction limited performance. Simultaneously, this technology also allows ultra-rapid focusing without having to move either the stage or the objective lens. We perform optical simulations to demonstrate the degree of correction that can be achieved.
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Affiliation(s)
- Zvi Kam
- Weizmann Institute of Science, Rehovot 76100, Israel.
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Mu Q, Cao Z, Hu L, Li D, Xuan L. An adaptive optics imaging system based on a high-resolution liquid crystal on silicon device. OPTICS EXPRESS 2006; 14:8013-8018. [PMID: 19529171 DOI: 10.1364/oe.14.008013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
An adaptive optics imaging system is introduced in this paper. A high resolution liquid crystal on silicon (LCOS) device was used as a phase only wave front corrector instead of a conversional deformable mirror. The wave front aberration was detected by a Shack-Hartmann (SH) wave front sensor, which has lambda/100 rms wave front measurement accuracy. Under this construction 0.09lambda (lambda=0.6328microm) Peak to Valley correction precision was reached. Further more, some low frequency hot convection turbulence induced by an electric iron was compensated in real time at the same precision. The Modulation Transfer Function (MTF) of this system was also measured before and after wave front correction. Under the active correction of LCOS, the system reached the diffraction limited resolution approximately 65l p/mm on the horizontal direction. All of this showed the ability of using this device in high resolution, low temporal turbulence imaging system, such as retinal imaging, to improve the resolution performance.
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Booth M, Wilson T, Sun HB, Ota T, Kawata S. Methods for the characterization of deformable membrane mirrors. APPLIED OPTICS 2005; 44:5131-9. [PMID: 16121800 DOI: 10.1364/ao.44.005131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We demonstrate two methods for the characterization of deformable membrane mirrors and the training of adaptive optics systems that employ these mirrors. Neither method employs a wave-front sensor. In one case, aberrations produced by a wave-front generator are corrected by the deformable mirror by use of a rapidly converging iterative algorithm based on orthogonal deformation modes of the mirror. In the other case, a simple interferometer is used with fringe analysis and phase-unwrapping algorithms. We discuss how the choice of singular values can be used to control the pseudoinversion of the control matrix.
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Affiliation(s)
- Martin Booth
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK.
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