| 摘要 |
PURPOSE:To obtain a device which is small-sized and high in accuracy, by using a PSD as a focusing detection element. CONSTITUTION:An optical image of an object O forms an image in a pair of PSD1 and PSD2 placed on the conjugate surface to a film F through a moving mirror QRM, a pair of wedge type optical elements STP and a semitransparent mirror HM. Their outputs I11, I12 and I21, I22 are inputted to position detecting circuits PDC1, PDC2, and a ratio I01 signal to a sum signal of a difference signal of I11 and I12, and an I02 signal corresponding to said signal are provided to a differential amplifier A4. When a servomotor M is driven so that its output IM becomes minimum, focusing is obtained. In this way, a device which is small-sized and high in accuracy is obtained. |
