Patent ID: 7370968

Claim:
An ocular depth dimension measurement apparatus which performs non-contact measurement of an ocular depth dimension of an examinee's eye, the apparatus comprising: a measurement light projecting optical system including a light source emitting low coherent light, and arranged to make a part of the light from the light source into first measurement light and a part of the light from the light source into second measurement light, and to collect the first measurement light on a first measurement surface of the eye and the second measurement light on a second measurement surface of the eye; an interference optical system including: a separation unit arranged to separate a part of the light from the light source to make it into reference light; and an optical path length changing unit arranged to change optical path length of the reference light, arranged, while changing the optical path length of the reference light, to synthesize the first measurement light reflected by the first measurement surface and the reference light and to make them interfere with each other so as to photo-receive, and to synthesize the second measurement light reflected by the second measurement surface and the reference light and to make them interfere with each other so as to photo-receive, and arranged to obtain interference signals of respective interference light; and a calculation part arranged to calculate the ocular depth dimension of the eye based on the obtained interference signals and a driving result of the optical path length changing unit.