Abstract: A communication optical system having a compact structure and capable of preventing crosstalk is disclosed. The communication optical system includes a light source, a light-receiving element and a beam-splitting member. The beam-splitting member performs one of transmission and reflection towards an incident/emergent port, and performs one of reflection and transmission towards the light-receiving element of a second light beam from the incident/emergent port. The light source and the light-receiving element are arranged on the same side with respect to the beam-splitting member.

Abstract: An optical transmission device for providing stable communication with a partner device by reducing errors in optical axis misalignment. The errors are caused by uneven distribution of the light intensity in a received light beam resulting from atmospheric microscopic fluctuations. One embodiment includes a transmission and receiving unit, which employs two photodetectors, one aligned with and the other misaligned with the optical axis of the optical transmission device. Other embodiments employ a movable means for shifting a photodetector or a lens unit relative to the optical axis of the optical transmission device.

Abstract: An optical transmission device for providing stable communication with a partner device by reducing errors in optical axis misalignment. Such errors are caused by uneven distribution of the light intensity in a received light beam resulting from atmospheric microscopic fluctuations. A cross pattern filter having at least two cross patterns is used at a partner transmission device side with respect to an incident direction detecting means, and arranged so that a cross pattern generated on the position detecting photodetector by the cross pattern filter and parting lines for dividing a position detecting photodetector do not overlap with each other, but intersect with each other.

Abstract: A color separation prism in which are arranged, in the order according to the direction in which the light from the objective travels: a first prism which extracts a predetermined wavelength component; a first air gap; a second prism which extracts a predetermined wavelength component; a second air gap; and third and fourth prisms that are joined to each other, wherein, in particular, a light reflected by the joint plane is totally reflected by a surface adjacent the second air gap and guided to an image pickup device.

Abstract: The present invention relates to an apparatus for controlling the lens position of a zoom lens. The zoom lens comprises a plurality of lens units movable along the optical axis for zooming, a focal length setting unit for setting the focal length of the zoom lens, an object distance setting unit for setting an object distance, a store containing a plurality of inherent coefficients and an arithmetic logic unit which specifies focal length information and object distance information as variables, and uses the coefficients in calculating a position to which a lens unit should move.

Abstract: An optical apparatus comprising an objective lens for producing a light bundle, a color separation prism receptive of the light bundle for producing two or more component light beams, two or more solid-state image sensors arranged behind the respective spaces between the exit faces of the prism in fixedly secured relation, and optical means arranged in all but one of the spaces between the exit faces of the prism and the image sensors to vary the lengths of the optical paths.

Abstract: An imaging device having solid-state image sensors coupled to a prism for separating the light from an objective optical system, wherein a solder layer capable of adhering to a glass substance is formed on a part of said prism or on a glass plate adhered to said prism, and a gap between said solder layer and a solderable material formed on a casing of said solid-state image sensor is filled with a low-melting metal to unite the two. The metal layer thickness of the solder layer is disposed to cause the light receiving surface of the image sensor to correspond to a predetermined imaging plane of the imaging device.