| 摘要 |
PURPOSE:To enable preparation of a focus detecting device of high performance by employing two sets of optical systems so that an image on each light-receiving surface is made clear when the relative position of the respective image with the light-receiving surface reaches a prescribed relation. CONSTITUTION:By using two lenses for measuring distance, an image of the same object is received by two photo-electric devices having a light-receiving surface respectively, while the relative position of the image and the light-receiving surface is made changeable. Next, a device for the change is made to operate in linkage with the change in the optical length from the aforesaid lenses to the light-receiving surfaces so as to make clear the images on the light- receiving surfaces when the aforesaid relative position has a prescribed relation, and an inspection is conducted under the condition. For example, the lenses 15 and 16 are moved in the directions of 15a to 15c and 16a to 16c in accordance with the change in the position of the object to be measured from an infinite distance position O1 to O2 and O3 so as for the focus to be formed on the light- receiving surfaces 5 and 6 just when the relations of relative positions of the images are in accord, whereby the highly-precise measurement of distance is made possible. A number of variants may be considered in this method. |
