Distance measuring apparatus

DETAILED DESCRIPTION It is an object of the invention to avoid the described disadvantages of the prior art by providing a distance measuring apparatus which projects a light beam to an object being photographed or determined and receives reflected light therefrom and modulates the intensity thereof in accordance with the angle of incidence thereof so that an output representing a determined distance is derived as a function of the angle of incidence of reflected light.
It is another object of the invention to provide a distance measuring apparatus which modulates the intensity of reflected light from an object being determined by passing it through a critical angle prism.
The invention provides the following beneficial results: (1) An accurate determination is enabled since an intensity modulated light output increases significantly even for a very small change in the angle of the reflected light from the object being determined.
(2) Distance information can be simply derived independently from the intensity of the light beam used for illumination or the reflectivity of the object being determined, by utilizing an output detecting the intensity of a first light component which is not subject to a modulation and another output detecting the intensity of a second light component which has been subjected to an intensity modulation.
(3) No moving parts are used, avoiding any degradation over a repeated use and increasing the reliability.
(4) Since moving parts are entirely avoided, the number of parts used as well as the number of assembly steps required are both reduced, providing an inexpensive arrangement.
(5) The absence of a mechanical interlocking assembly affords a greater freedom in its lay-out when implementing the invention into a camera, thus facilitating the design.
(6) Since the illuminating means and signal processor are completely separate from each other, the length of the base line on the camera can be considerably increased as compared with a conventional arrangement, and hence an improvement in the accuracy of measurement can be expected