초록 ▼

A focus condition of an objective lens is detected on the basis of a lateral shift of two images formed by first and second light fluxes which are transmitted through right- and left-hand halves of the lens, respectively. In order to separate the first and second light fluxes, there is arranged an a

A focus condition of an objective lens is detected on the basis of a lateral shift of two images formed by first and second light fluxes which are transmitted through right- and left-hand halves of the lens, respectively. In order to separate the first and second light fluxes, there is arranged an array of triangle prisms each having first and second surfaces which are inclined symmetrically with respect to the optical axis of lens by a critical angle so that one of the light fluxes is transmitted through the one of the surfaces, but is totally reflected by the other surface of each prism. The first and second light fluxes transmitted through the prisms are received by an array of light receiving elements in such a manner that the first and second light fluxes are selectively received by odd and even numbered light receiving elements, respectively.

대표청구항 ▼

In a method of detecting a focusing condition of an objective lens for forming an image of an object on a predetermined focal plane by selectively introducing first and second light fluxes each emanating from at least a part of respective one of first and second halves of objective lens divided alon

In a method of detecting a focusing condition of an objective lens for forming an image of an object on a predetermined focal plane by selectively introducing first and second light fluxes each emanating from at least a part of respective one of first and second halves of objective lens divided along a plane including the optical axis of objective lens, onto first and second light receiving means, respectively, and by processing photoelectrically converted outputs supplied from the first and second light receiving means, the improvement comprising introducing the first and second light fluxes into first and second light splitting means arranged between the objective lens and the first and second light receiving means, respectively, said first and second light splitting means including first and second optical surfaces, respectively, each of which is formed by an interface between higher refractive index material and lower refractive index material viewed in a light propagating direction and said first and second optical surfaces being inclined symmetrically with respect to the optical axis by such angles that the first light flux is transmitted through the first optical surface, but is totally reflected by the second optical surface and that the second light flux is transmitted through the second optical surface, but is totally reflected by the first optical surface.