PURPOSE:To quickly check a position of a ring image and reflect-in of an image of an eyelid by conjugating with the image formation surface of the ring image, providing plural photodetectors centering around an optical axis of an optical system, and providing a signal processing circuit for deciding a state of the ring image by its output signal. CONSTITUTION:A ring-like illuminating light radiated to the cornea Ec of an eye E to be examined from a ring illumination 201 becomes ring images I1, I2 and received by a two-dimensional image pickup element 206 as a ring-like reflected image I by a cornea reflection. Also, the same ring image is formed neously to a check photodetecting part 207, as well, consisting of plural one- dimensional photodetectors provided on the conjugate surface being roughly conjugate to the image formation surface of the ring image of the the two-dimensional image pickup element 206, and also, radially centering around an optical axis being orthogonal to an optical axis O of a cornea distance measuring optical system 200. Subsequently, a part of the photodetected ring image is outputted to a signal processing circuit through a frame memory from the check photodetecting part 207, and whether the ring image is in a proper prescribed position or not is decided.
展开▼
