| 摘要 |
PURPOSE:To attain the detection of focus on an optical axis and out of the optical axis by curving a projection pattern corresponding to the astigmatism characteristic of a light projecting lens in order to agree the focusing position of a projection pattern image. CONSTITUTION:An illuminating device includes a light source 4, the projection pattern 21 arranged just before the light source 4 and the light projecting lenses 3 and 20 which project the projection pattern 21 on an object and the projection pattern 21 is formed to be curved corresponding to the astigmatism characteristic of the light projecting lens 3 in order to agree the focusing position of the projection pattern image on the object on the optical axis and out of the optical axis. Namely, focusing position of the projection pattern image projected on the object is agreed both on the optical axis and out of the optical axis. Thus, the detection of focus is always attained on the optical axis and out of the optical axis even if the focus detecting area on the object is altered according to the length of the focal distance of a used photographing lens 1. |
