| 摘要 |
PROBLEM TO BE SOLVED: To provide a focus detector having a wide focus detection range, as for a focus detector using a double mode waveguide. SOLUTION: Light emitted from a light source 1 is condensed by light condensing optical systems 3 and 4 so as to irradiate an object to be inspected 5. The light reflected by the object to be inspected 5 is made incident from the incident end faces of double mode waveguides 21 to 25 and transmitted. The inclination of electric field distribution of the light transmitted through the double mode waveguides 21 to 25 is detected by detecting means 51 to 55. In this case, a splitting means 10 is arranged so as to split light reflected by the object to be inspected into luminous fluxes equal to the number of the double mode waveguides and to guide respective fluxes to the incident end faces of plural double mode waveguides. Plural double mode waveguides are arranged so that each center of the incident end face may be shifted from the optical axis of the luminous flux guided by the splitting means. |
