Shift- and scale-invariant pattern recognition using morphological phase-only correlation

We propose a non-linear correlation to realize scale-invariant recognition, called shift- and scale-invariant morphological phase-only correlation (SSIMPC), which is a combination of radial harmonic filter (RHF) and morphological phase-only correlation (MPC). We form SSIMPC using phase-only RHFs (PORHF) instead of common RHFs in every sub-correlations of morphological radial harmonic correlation (MRHC). Computer simulation results demonstrate that the performance of SSIMPC is better than that of MRHC in discrimination and robustness against non-Gaussian noise, such as salt-and-pepper noise and cluttered background, and above of all, SSIMOC realizes approximately full scale-invariance. In addition, we devise an optoelectronic scheme, which is identical to the setup for MPC, to implement SSIMPC.     

Algorithm of far-field centre estimation based on phase-only matched filter

Estimation of the far-field centre is carried out in beam auto-alignment. In this paper, the features of the far-field of a square beam are presented. Based on these features, a phase-only matched filter is designed, and the algorithm of centre estimation is developed. Using the simulated images with different kinds of noise and the 40 test images that are taken in sequence, the accuracy of this algorithm is estimated. Results show that the error is no more than one pixel for simulated noise images with a 99% probability, and the stability is restricted within one pixel for test images. Using the improved algorithm, the consumed time is reduced to 0.049s.     

三区位相型三维超分辨光瞳滤波器的优化设计

用Matlab优化工具箱,采用非线性规划,对三区位相型(π-0-π型)光瞳滤波器进行了优化设计。结果显示,所设计的滤波器较好地实现了横向和轴向的三维超分辨,且轴向超分辨能力优于横向。该滤波器结构简单,容易实现。     

Influence of ophthalmic lenses in the illuminance originated at a peripheral glare source and reaching the eye

To study the influence of glare on the visual performance of a subject wearing an ophthalmic lens, it is useful to know how the lens affects the illuminance reaching the eye. In this paper, considering spherical standard ophthalmic lenses and defining the relative illuminance, E_r, as the quotient between the illuminance at the cornea with and without lens, a methodology to evaluate E_r in terms of easily determined parameters is developed. Three effects are considered, pupil size variation of the system with and without lens; lateral shifts of rays transmitted through the lens and reflections at the lens. Calculations are experimentally verified employing 5 organic ophthalmic lenses of ±6; ±4 and 0.12 dioptres and 2 glass plane parallel plates 1.95 and 6.6 mm thick. Using a photometer whose sensor is 12 mm apart from the lens and 740 mm apart from a glare source subtending an eccentricity angle of 9.6°, it results E_r=1.204 for the 6 dioptres lens and E_r=0.803 for the −6 dioptres one if sensor diameter is 10 mm while, for a 719 mm distance and a 10° angle, E_r=0.922 for the thin plate and a 30 mm sensor and E_r=1.006 for the thick plate and a 10 mm sensor. Experimental and theoretical results differ in less than 3%.     

Golay6结构复杂光瞳成像研究

Golay6为非冗余的复杂光瞳结构,导出Golay6结构复杂光瞳的光瞳函数解析式和点扩散函数的解析式,在此基上用Matlab软件模拟了调制传递函数图像,并对目标图像进行模拟成像。针对所成像对比度下降问题,在不含噪声和含噪声情况下分别进行了讨论,利用分数阶微分算子对模拟所得图像进行图像增强,结果表明经分数阶微分算子空域增...     

Discretized amplitudemodulated phase-only filter

The amplitude-modulated phase-only filter (AMPOF) effectively utilizes both amplitude and phase information to obtain a narrower and larger autocorrelation peak. To make it readily suitable for real-time target recognition applications, we consider discretizing both its amplitude and phase. Accordingly, both amplitude and phase of the AMPOF are ternerized to yield improved performance statistics of the correlator.     

Spatial Temporal Analysis of Electrically-Addressable Phase-Only Spatial Light Modulator

An optically addressed parallel-aligned nematic-liquid-crystal spatial light modulator (PAL-SLM) has been studied as a dynamic phase-only modulation device. A computer control feature of the spatial light modulator is strongly desired for practical applications. For those demands, an electrically-addressable phase-only spatial light modulator has been developed to combine a liquid crystal display (LCD) with a PAL-SLM (LCD-coupled PAL-SLM) and its performance has been reported. However, a temporal characteristic especially two-dimensional (2D) response has not been discussed before. In this paper, 2D response analysis system has been constructed by using a high-speed complementary Metal-Oxide-Semiconductor (CMOS) camera (1000 frames/sec) and the 2D-modulation characteristic of the LCD-coupled PAL-SLM has been observed. As a result, the LCD has a spatially non-uniform modulation characteristic due to a scanning addressing. It has the potential to cause problems in high speed switching for a computer generated hologram. On the other hand, the spatial non-uniformity has not been observed with the LCD-coupled PAL-SLM.     

双焦镜片的设计、应用和开发

本文通过对当今眼镜市场上传统产品的比较及配戴使用效果的分析，结合眼睛的调节与适应原理，引出一传统消费的误区，提出了一种眼镜消费的新空间即双焦镜片的应用开发。本文概述了双焦镜片设计的基本原理，并对符合眼睛调节的双焦镜片片形设计、光度调节以及像差理论进行了论证。结论是：双焦镜片可解决中老年眼疾患者看远近物体时需配戴两副不同光焦度眼镜的痛苦；双焦镜片同样适用于年轻人，可缓解眼睛的调节疲劳，防止度数的上升。充分开发双焦镜片的功能，对于卫生用眼，后天防治眼疾有着重要意义。     

Phase-only filtering based on sliced orthogonal nonlinear generalized decomposition

The sliced orthogonal nonlinear generalized (SONG) decomposition and correlation have been demonstrated to be powerful tools in digital image processing and promising for nonlinear optical information processing. In this paper, we propose an optical phase-only filtering system based on SONG decomposition (PBS), in which the phase-only filtering of the target and the input scene binary slices are performed separately by pairs and then added together. We numerically show that the PBS has extremely high and sharp output correlation peak compared with other optical correlators. Furthermore, such a SONG decomposition based phase-only filtering naturally inherits the nature of SONG decomposition, which has strong robustness to additive Gaussian noise and substitutive noise, and also the high light efficiency of phase-only filtering. We demonstrate that the PBS may serve as an optimized optical correlation scheme, which is promising in nonlinear optical pattern recognition.     

大口径红外成像系统的光学设计

推导了以反射式两镜系统为主体的红外成像系统中满足光瞳匹配要求的转像透镜的高斯光学参量与两镜系统参量的关系式。当选定红外焦平面的冷屏直径及到焦面的距离后，转像透镜与两镜系统的高斯光学参量之间必须满足这个关系式，才能做到光瞳匹配，这就是冷屏为系统的出瞳．而入瞳是主反射镜的口径。消像差由主镜、副镜的非球面及转像透镜上的一个非球面承担。用实例计算验证了所推导出的公式的可靠性，红外系统的口径取为250mm，红外接收器的冷屏直径为5mm，冷屏到红外像面的距离为20mm。两镜系统主镜的曲率半径选定为-1000mm及-800mm两个值，两镜系统焦距为2000mm，1500mm及1000nm三个。共计算了六种结构参量不同的系统。