振幅型光栅法人眼调制传递函数测定的理论分析  

Theoretical analysis of measuring eye modulation transfer function by amplitude grating

作　　者：滕坚[1] 金晨晖[1] 杨伟斌[1] 

机构地区：[1]深圳职业技术学院,广东省深圳市518055

出　　处：《中国组织工程研究与临床康复》2007年第40期8165-8168,共4页Journal of Clinical Rehabilitative Tissue Engineering Research

摘　　要：目的:介绍测量视网膜调制传递函数的方法和光学原理,验证振幅型正弦光栅加零级空间滤波的方法测量视网膜调制传递函数使测量仪器小型化的可行性。方法:目前测量仪器中获得两相干点光源主要是使用平行板法、双道威棱镜法和光栅法3种,从理论上分析比较3种方法的优劣性,并重点分析矩形光栅、振幅型正弦光栅的各级衍射光强分布特点。结果:①平板法和双道威棱镜法可获得两相干点光源,也是在视网膜调制传递函数测量仪中应用比较成熟的技术,其光学原理简单,获得相干点光源的相干性良好,光强稳定。另外,使用双道威棱镜法时,可以用电位带动反射镜的移动来控制两点光源的间距,易于装置的智能化控制,但所设计的仪器外观尺寸较大,移动性较差,不利于测量装置的手持式和小型化发展。②矩形光栅法可以实现仪器的小型化,但由于矩形光栅的衍射图样是单缝衍射图样与多光束干涉图样相互调制的结果,即衍射光强的多光束干涉条纹干扰测量结果。③振幅型正弦光栅的透过率函数可以实现0￣1,以余弦波形式对入射光波产生振幅调制,且衍射光强只有三级谱线(0级和±1级),且±1级谱线的光强分布具有对称性,只要进行零级空间滤波,就可以得到作为视标调制度的两个点光源。结论:振幅型正弦光栅加零级空间滤波可以获得相干性良好相干点光源,并且可以实现测量仪器的小型化。AIM： To introduce the way to measure retinal modulation transfer function （MTF） and the optical theory, so as to testify the theoretical possibility to minimize dramatically the instrument of measuring retinal MTF by using amplitude sine grating and filtering of the zero rank phase interference sine grating. METHODS： There were so far three approaches to acquire two interfered spot light source including the ways by parallel plate, Dual Dove prism, and grating, respectively. The advantages and disadvantages of these three measurements were analyzed and compared theoretically. Each phase light intensity characteristic was analyzed by means of rectangular grating and amplitude sine grating. RESULTS： ①Two interfered spot light sources were obtained by using parallel plate and Dual Dove prism, which were the mature technology in the measurement of MTF, Their optical principle was simple, and the interference ability of two acquired interfered light spot sources was desirable with stable light intensity. In addition, for the way of Dual Dove prism, it was easily realized to inteUigentize the controlling of the instrument through the eclectically-drove movement of mirror to control the distance between two interfered spot light sources. But the size of this kind of design was so big that it was difficult to move and hard for hand-held design. ②lnstrument could be minimized by using rectangular grating, but because the diffraction pattern of rectangular grating was the result of modulation between diffraction of one narrow slit and the interference of multiple interfered light beam, that was to say its diffraction intensity had multiple light beam which affected the MTF measurement. ③By the form of cosine waves to modulate the amplitude of the incident light, the transmitting function of amplitude sine grating can be realized the change from 0 to 1. The diffraction pattern of amplitude sine grating included three phases diffraction （grade 0 and grade ±1）, In addition, the intensity of grade ±1 was

关 键 词：调制传递函数 对比敏感度 平板法 双道威棱镜法 矩形光栅 正弦光栅 

分 类 号：R318.08[医药卫生—生物医学工程]