Artificial compound-eye optics have been used for three-dimensional information acquisition and display. It also enables us to realize a diversity of coded imaging process in each elemental optics. In this talk, we in...
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ISBN:
(纸本)9781628413526
Artificial compound-eye optics have been used for three-dimensional information acquisition and display. It also enables us to realize a diversity of coded imaging process in each elemental optics. In this talk, we introduce our single-shot compound-eye imaging system to observe multi-dimensional information including depth, spectrum, and polarization based on compressive sensing. Furthermore it is applicable to increase the dynamic range and field-of-view. We also demonstrate an extended depth-of-field (DOF) cameras based on compound-eye optics. These extended DOF cameras physically or computationally implement phase modulations to increase the focusing range.
In modern high-NA optical scanning instruments, like scanning microscopes, the refractive-index mismatch between the sample and the immersion medium introduces a significant amount of spherical aberration when imaging...
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In modern high-NA optical scanning instruments, like scanning microscopes, the refractive-index mismatch between the sample and the immersion medium introduces a significant amount of spherical aberration when imaging deep inside the specimen, spreading out the impulse response. Since such aberration depends on the focalization depth, it is not possible to achieve a static global compensation for the whole 3D sample in scanning microscopy. Therefore a depth-variant impulse response is generated. Consequently, the design of pupil elements that increase the tolerance to this aberration is of great interest. In this paper we report a hybrid technique that provides a focal spot that remains almost invariant in the depth-scanning processing of thick samples. This invariance allows the application of 3D deconvolution techniques to that provide an improved recovery of the specimen structure when imaging thick samples. (C) 2009 Optical Society of America
The phase mask plays a key role in wavefront coding systems. In order to find the phase coding device with better performance, a new kind of phase mask--five times phase mask is proposed, based on cubic phase mask in ...
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ISBN:
(纸本)9780819474001
The phase mask plays a key role in wavefront coding systems. In order to find the phase coding device with better performance, a new kind of phase mask--five times phase mask is proposed, based on cubic phase mask in common use, and its coding properties are studied in the paper. First of all, the reason of depressing spherical aberration is analyzed by deriving the asymptotic solution to OTF of the wavefront coding systems with five times phase mask. And then we compare the effects of inhibition of spherical aberration when place the cubic and five times phase mask respectively. Finally, the experimental simulation is done. The results show that on the specific threshold (MTF=0.1) the normalized bandwidth of the system with five times phase mask can be reached 3 times of that with the cubic one;at the same characteristic frequency (u = 0.5), the MTF value is 2 times of that in system with cubic one. Both the MTF consistency in the low frequency region and the PTF consistency in the high frequency region of the system with a five times phase mask are better than those with a cubic one in condition of different spherical aberration. Compared with the cubic phase mask, the five times phase mask performs better in inhibition of spherical aberration.
We characterize the three-dimensional (3-D) double-helix (DH) point-spread function (PSF) for depth-variant fluorescence microscopy imaging motivated by our interest to integrate the DH-PSF in computational optical se...
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We characterize the three-dimensional (3-D) double-helix (DH) point-spread function (PSF) for depth-variant fluorescence microscopy imaging motivated by our interest to integrate the DH-PSF in computational optical sectioning microscopy (COSM) imaging. Physical parameters, such as refractive index and thickness variability of imaging layers encountered in 3-D microscopy give rise to depth-induced spherical aberration (SA) that change the shape of the PSF at different focusing depths and render computational approaches less practical. Theoretical and experimental studies performed to characterize the DH-PSF under varying imaging conditions are presented. Results show reasonable agreement between theoretical and experimental DH-PSFs suggesting that our model can predict the main features of the data. The depth-variability of the DH-PSF due to SA, quantified using a normalized mean square error, shows that the DH-PSF is more robust to SA than the conventional PSF. This result is also supported by the frequency analysis of the DH-PSF shown. Our studies suggest that further investigation of the DH-PSF's use in COSM is warranted, and that particle localization accuracy using the DH-PSF calibration curve in the presence of SA can be improved by accounting for the axial shift due to SA. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)
Iris recognition is the most reliable method in personal identification. However, the current fixed-focus iris imaging system has small depth of field(DOF), which limits the wide application of the iris recognition sy...
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ISBN:
(纸本)9780819495020
Iris recognition is the most reliable method in personal identification. However, the current fixed-focus iris imaging system has small depth of field(DOF), which limits the wide application of the iris recognition system. This paper presents the design method and optimization of a phase mask based iris imaging system. Through wavefront coding, it can extend the DOF and enhance the convenience of iris image acquisition. Through analyzing the modulation transfer function and optical parameters of the cubic phase mask, we can get the wavefront coding iris imaging system's optimal parameter and it's structure. Experimental results show that the cubic phase mask based iris imaging system has larger DOF and better imaging performance.
A high-speed digital holography based on a liquid crystal Spatial Light Modulator (LC-SLM) is presented. The production of multi-beam and control of their delay time can be achieved by controllable wavefront coding th...
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ISBN:
(纸本)9780819499608
A high-speed digital holography based on a liquid crystal Spatial Light Modulator (LC-SLM) is presented. The production of multi-beam and control of their delay time can be achieved by controllable wavefront coding theory. In this paper, a Dammann phase grating was designed using a SLM to product multi-beam for extremely high speed digital holographic imaging. The required beam deflection could be obtained by adjusting programmable phase mask for controlling the spatial diffraction of input beam. The framing time is decided by interval beam angles and the distances between input plane and record plane. Theoretical derivate of generation multi beams based on SLM was proposed, and phase recover software was also made.
We propose a resolution enhancement method for mobile small f-number compact imaging systems based on wavefront coding and superresolution image processing. wavefront coding increases the focus depth of an optical sys...
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We propose a resolution enhancement method for mobile small f-number compact imaging systems based on wavefront coding and superresolution image processing. wavefront coding increases the focus depth of an optical system and produces point spread functions (PSFs) with similar characteristics at different field and defocus positions. The designed target wavefront is realized as a combination of wavefront errors of each rotationally symmetric lens, without including an additional phase plate. Finally, using one deconvolution filter containing all the characteristics of the PSFs, we achieve high resolution, breaking the diffraction limit of small f-number and the resolution limit of the image sensor by super-resolution image processing. (c) 2008 Optical Society of America.
The wavefront coding technology is an effectively method for extending the depth of field. However, the phase delayed by the phase mask changes with light wavelength, and the chromatic aberration is caused by chromati...
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The wavefront coding technology is an effectively method for extending the depth of field. However, the phase delayed by the phase mask changes with light wavelength, and the chromatic aberration is caused by chromatic dispersion of the optical elements. The modulation transfer function (MTF) of the cubic phase mask (CPM) system is derived with considering the axial chromatic aberration and optical path difference variation with wavelength, and the wavelength behavior of CPM system is analyzed in details. We yield that the MTF is approximately wavelength invariant within a certain frequency bandwidth, and the bandwidth is nearly inverse proportional to wavelength and varies with axial chromatic aberration. The effect induced by dispersion of the CPM material is very weak. If the CPM system is illuminated by wideband spectral light and the ACA exists, then the frequency bandwidth may become narrower than the monochromatic case, and the position of image sensor can be relocated to balance frequency bandwidth among all wavelengths. (C) 2011 Elsevier B.V. All rights reserved.
作者：
Yan, FengChinese Acad Sci
Changchun Inst Opt Fine Mech & Phys Opt Technol Res Ctr Changchun 130033 Peoples R China Chinese Acad Sci
Grad Sch Beijing 100084 Peoples R China
wavefront coding (WFC) technology can extend the depth of focus of an optical system, which makes the application of this technology to space cameras extremely attractive. This paper introduces the application of wave...
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wavefront coding (WFC) technology can extend the depth of focus of an optical system, which makes the application of this technology to space cameras extremely attractive. This paper introduces the application of wavefront coding to three-mirror anastigmatic optical systems. A transition model is established, in which the secondary mirror is regarded as the wavefront coding element and redesigned according to mathematical calculation. A comparison of modulation transfer function (MTF) behavior between the traditional system and the innovative system with wavefront coding technology is provided. The MTF behavior of both on-axis and off-axis field-of-view points remains the same in spite of the extended depth of focus. It is also observed that the system becomes very insensitive to aberration related to defocus through WFC technology. Errors in optical design and its improvement are discussed. The linear transition model is proven to be an acceptable one. Finally, an extension factor for the depth of focus is defined, and its effect is presented graphically. (C) 2008 Society of Photo-Optical Instrumentation Engineers.
wavefront coding (WFC) used in 2D barcode scanners can extend the depth of field into a great extent with simpler structure compared to the autofocus microscope system. With a cubic phase mask (CPM) employed in the ST...
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ISBN:
(纸本)9780819470126
wavefront coding (WFC) used in 2D barcode scanners can extend the depth of field into a great extent with simpler structure compared to the autofocus microscope system. With a cubic phase mask (CPM) employed in the STOP, blurred images will be obtained in charge coupled device (CCD), which can be restored by digital filters. Direct methods are used widely in real-time restoration with good computational efficiency but with details smoothed. Here, the results of direct method are firstly filtered by hard-threshold function. The positions of the steps can be detected by simple differential operators. With the positions corrected by projection algorithm, the exact barcode information is restored. A wavefront coding system with 7mm effective focal length and 6 F-number is designed as an example. Although with the different magnification, images of different object distances can be restored by one point spread function (PSF) with 200mm object distance. A QR code (Quickly Response Code) of 31mm X 27mm is used as a target object. The simulation results showed that the sharp imaging objective distance is from 80mm to 355mm. The 2D barcode scanner with wavefront coding extends field depth with simple structure, low cost and large manufacture tolerance. This combination of the direct filter and projection algorithm proposed here could get the exact 2D barcode information with good computational efficiency.
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