OPTICAL SYSTEM DESIGN METHOD BASED OTF FOR OPTICAL ENCODER HAVING DIFFERENT DISTANCES OF IMAGE AND OBJECT, AND OPTICAL ENCODER THEREOF

摘要

An optical system design method of an optical encoder according to the present invention includes a step of receiving information on design condition about an optical system including a pupil lattice, an image lattice, and an object lattice and a step of determining an optical system structure according to the information on the design condition by determining a slit pitch of the object lattice, the slit pitch of the image lattice, the distance between the pupil lattice and the image lattice, and the distance between the pupil lattice and the object lattice based on the information on the design condition. The information on the design condition includes the information on a wavelength of irradiated light, the slit pitch of the pupil lattice, and a ratio between Z1, which is an object distance between the pupil lattice and the object lattice, and Z2, which is an image distance between the pupil lattice and the images lattice. The slit pitch of the object lattice and the slit pitch of the image lattice are determined by applying a modulation frequency of the object lattice and the reverse of a reverse modulation frequency of the image lattice. The Z1, which is an object distance between the pupil lattice and the object lattice, is the one selected among multiples on a modulation intensity change cycle, and the Z2, which is an image distance between the pupil lattice and the images lattice, is calculated according to the ratio on the Z1. [Reference numerals] (100) Control device;(102) User interface part;(104) Memory part;(106) Display controller;(108) Display module;(AA) Optical system designing part