| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical element used in a focus detector which can reduce its size and cost with a small number of parts and a simple structure. <P>SOLUTION: A focus detector 100 comprises a light source 10 for emitting light onto an object 60, a two-divided light receiving element 80 for detecting light reflected by the object 60, and an optical element 20 that collects the light from the light source 10, emits the light onto the object 60 through an objective lens 50, collects light reflected by the object 60 through the objective lens 50, and transmits the light to the two-divided light receiving element 80. The optical element 20 includes an entrance surface 20d that the light from the light source 10 enters, a first reflection surface 20b that reflects the light, a refractive surface 20a that concentrates the light reflected by the first reflection surface 20b onto the object 60 and concentrates the light reflected by the object 60 onto the two-divided light receiving element 80, a second reflection surface 20c that reflects the light concentrated by the refractive surface 20a in the direction of the two-divided light receiving element 80, and an exit surface 20e which the light exits to be transmitted to the two-divided light receiving element 80. <P>COPYRIGHT: (C)2012,JPO&INPIT |
