Abstract: A free space optics communication apparatus which performs optical axis correction with high accuracy is disclosed. The free space optics communication apparatus of the present invention includes a first light receiving element and a second light receiving element, a light converging optical system which converges a light flux incident from the outside to form a spot of the light flux on each of light receiving surfaces of the first and second light receiving elements, and information producing section which combines outputs from the first and second light receiving elements to produce information on positions of the spots. The spots formed on the light receiving surfaces of the first and second light receiving elements have a point-symmetrical relationship.

Abstract: An optical-space transmission apparatus for use in communication by using light propagating in a space includes a light-receiving unit, an optical system including a movable mirror and introducing light incident thereon to the light receiving unit with the movable mirror, a controller controlling drive of the movable mirror, and a detecting unit detecting an intensity of the light received in the light-receiving unit. The controller modifies a control characteristic of the movable mirror in accordance with a change in the received-light intensity.

Abstract: In a disclosed spatial optical communication apparatus, the optical-axis deviation correction is possible at the same time for both high-speed angular variation with a small amplitude and low-speed angular variation with a large amplitude, and the apparatus has a function of correcting the optical-axis deviation whose application range is wide and whose correction ability is high. To achieve such function, the spatial optical communication apparatus for performing communication between spaced locations with a light beam is provided with both a light deflecting unit set inside an optical system with a narrow variable angle range and a fast response speed, and an optical system driving unit set outside the optical system with a slow response speed and a wide variable angle range.

Abstract: A free-space optical communication apparatus includes a storage unit which stores angle-setting information for the mirror for communicating with each of the plurality of other apparatuses, a mirror driving unit which drives the mirror to an angle corresponding to the stored angle-setting information, an optical detecting unit which, on one occasion for communicating with a specified communication apparatus among the plurality of other apparatuses, detects the incident state of an optical beam sent from the specified apparatus, and a control unit which, based on the detected incident state of the optical beam, determines angle-correcting information for correcting the stored angle-setting information for the specified apparatus, and which, on the next occasion for communicating with the specified apparatus, uses the mirror driving unit to drive the mirror to an angle corresponding to the angle-setting information corrected by the angle-correcting information.

Abstract: An optical-space transmission apparatus for use in communication by using light propagating in a space includes a light-receiving unit, an optical system including a movable mirror and introducing light incident thereon to the light receiving unit with the movable mirror, a controller controlling drive of the movable mirror, and a detecting unit detecting an intensity of the light received in the light-receiving unit. The controller modifies a control characteristic of the movable mirror in accordance with a change in the received-light intensity.

Abstract: An optical free-space communication apparatus includes a first light-emitting source for emitting a first transmission optical beam having a plane of polarization in a predetermined direction, the first transmission optical beam being modulated according to a primary signal containing communication information, a second light-emitting source for emitting a second transmission optical beam having a plane of polarization perpendicular to the plane of polarization of the first transmission optical beam, the second transmission optical beam being modulated according to an auxiliary signal for angle detection, a transmitting optical system for emitting the first and second transmission optical beams out of the apparatus as optical beams each having a predetermined angle of divergence, and a driving unit for redirecting the outgoing paths of the first and second transmission optical beams, wherein the second transmission optical beam has a larger angle of divergence than the first transmission optical beam.

Abstract: A free space optics communication apparatus which performs optical axis correction with high accuracy is disclosed. The free space optics communication apparatus of the present invention includes a first light receiving element and a second light receiving element, a light converging optical system which converges a light flux incident from the outside to form a spot of the light flux on each of light receiving surfaces of the first and second light receiving elements, and information producing section which combines outputs from the first and second light receiving elements to produce information on positions of the spots. The spots formed on the light receiving surfaces of the first and second light receiving elements have a point-symmetrical relationship.

Abstract: An optical free-space communication apparatus includes a first light-emitting source for emitting a first transmission optical beam having a plane of polarization in a predetermined direction, the first transmission optical beam being modulated according to a primary signal containing communication information, a second light-emitting source for emitting a second transmission optical beam having a plane of polarization perpendicular to the plane of polarization of the first transmission optical beam, the second transmission optical beam being modulated according to an auxiliary signal for angle detection, a transmitting optical system for emitting the first and second transmission optical beams out of the apparatus as optical beams each having a predetermined angle of divergence, and a driving unit for redirecting the outgoing paths of the first and second transmission optical beams, wherein the second transmission optical beam has a larger angle of divergence than the first transmission optical beam.

Abstract: In a disclosed spatial optical communication apparatus, the optical-axis deviation correction is possible at the same time for both high-speed angular variation with a small amplitude and low-speed angular variation with a large amplitude, and the apparatus has a function of correcting the optical-axis deviation whose application range is wide and whose correction ability is high. To achieve such function, the spatial optical communication apparatus for performing communication between spaced locations with a light beam is provided with both a light deflecting unit set inside an optical system with a narrow variable angle range and a fast response speed, and an optical system driving unit set outside the optical system with a slow response speed and a wide variable angle range.

Abstract: A free-space optical communication apparatus includes a storage unit which stores angle-setting information for the mirror for communicating with each of the plurality of other apparatuses, a mirror driving unit which drives the mirror to an angle corresponding to the stored angle-setting information, an optical detecting unit which, on one occasion for communicating with a specified communication apparatus among the plurality of other apparatuses, detects the incident state of an optical beam sent from the specified apparatus, and a control unit which, based on the detected incident state of the optical beam, determines angle-correcting information for correcting the stored angle-setting information for the specified apparatus, and which, on the next occasion for communicating with the specified apparatus, uses the mirror driving unit to drive the mirror to an angle corresponding to the angle-setting information corrected by the angle-correcting information.

Abstract: An optical space communication apparatus for performing communication with an party apparatus by transmitting a light signal into a free space includes a signal selector for selecting and intercepting a beam including a light beam and background light from the party apparatus, a detector for detecting a beam via the signal selector, and a signal outputting device for comparing an output signal outputted from the detector when the signal selector intercepts the light beam from the party apparatus, with an output signal outputted from the detector when the signal selector does not intercept the light beam from the party apparatus, and for outputting a signal representing a difference between the output signals.

Abstract: An optical space communication apparatus for performing communication with an party apparatus by transmitting a light signal into a free space includes a signal selector for selecting and intercepting a beam including a light beam and background light from the party apparatus, a detector for detecting a beam via the signal selector, and a signal outputting device for comparing an output signal outputted from the detector when the signal selector intercepts the light beam from the party apparatus, with an output signal outputted from the detector when the signal selector does not intercept the light beam from the party apparatus, and for outputting a signal representing a difference between the output signals.

Abstract: In an optical space communication apparatus, a first electrical signal is converted into a first optical signal, and the first optical signal is transmitted to a partner apparatus in the form of a first light beam. A second light beam transmitted from the partner apparatus is received to thereby detect a second optical signal by a photodetector of the optical space communication apparatus. The second optical signal is converted into a second electrical signal. A transmission direction of the first light beam and reception direction of the second light beam are changed in a direction to maximize an intensity of the second electrical signal obtained by converting the second optical signal detected by the photodetector.

Abstract: An optical free-space communication apparatus includes a first light-emitting source for emitting a first transmission optical beam having a plane of polarization in a predetermined direction, the first transmission optical beam being modulated according to a primary signal containing communication information, a second light-emitting source for emitting a second transmission optical beam having a plane of polarization perpendicular to the plane of polarization of the first transmission optical beam, the second transmission optical beam being modulated according to an auxiliary signal for angle detection, a transmitting optical system for emitting the first and second transmission optical beams out of the apparatus as optical beams each having a predetermined angle of divergence, and a driving unit for redirecting the outgoing paths of the first and second transmission optical beams, wherein the second transmission optical beam has a larger angle of divergence than the first transmission optical beam.

Abstract: An optical space communication method is for communication with a laser as a radiative source and with a light signal therefrom propagating in the atmosphere. In the method, the communication is performed under the following conditions. In case a transmission distance of optical space communication is between 100 m inclusive and 200 m, the laser is a laser with an oscillation wavelength L (nm) in a wavelength range of between 967 run inclusive and 1110 nm or in a wavelength range of between 1165 nm inclusive and 1315 nm, whereas in case the transmission distance is not less than 200 m, the laser is a laser with an oscillation wavelength L (run) in a wavelength range of between 986 nm inclusive and 1090 nm or in a wavelength range of between 1225 nm inclusive and 1295 nm. At any position in a transmission path between a transmitter exit and a receiver entrance, an irradiance is set to at most 6.47.multidot.10.sup.(L-700)/500 (W/m.sup.

Abstract: This specification discloses a communication apparatus provided with light emitting means for generating transmission light modulated by an information signal, light receiving means for receiving modulated reception light, an optical member for reflecting one of the transmission light and the reception light and transmitting the other therethrough, a reflecting member for reflecting the transmission light emerging from the optical member to the transmission side and reflecting the reception light to the optical member, light splitting means for splitting part of the reception light obtained through the optical member, detecting means for detecting the positional state of the light obtained from the light splitting means, and driving means for rotatively driving the reflecting member about two axes in accordance with the positional state of the light detected by the detecting means.

Abstract: An optical space communication apparatus comprises a transmitter and a receiver. The transmitter has a main signal generator for producing a main signal, an auxiliary signal generator for producing an auxiliary signal in a frequency band different from that of the main signal, a combiner for combining the main signal with the auxiliary signal, an electro-optical converter for converting a combined signal of the main signal and the auxiliary signal into a light signal, and a transmission optical system for transmitting the light signal formed in light beam. The receiver has a reception optical system for receiving the light signal in light beam and a photo-electric converter for converting the light signal into an electric signal. The receiver further has a separator for separating the electric signal converted by the photo-electric converter into a main signal and an auxiliary signal, and an auxiliary signal detector for detecting the auxiliary signal separated by the separator.

Abstract: An optical space communication apparatus for propagating a beam of light through free space to thereby effect communication includes a transmitting device for transmitting a first optical signal converted into a beam of light, a expanse angle varying device for varying the angle of expanse of the beam of light into which the first optical signal has been converted, a level varying device for varying the output level of the first optical signal, a control device for controlling the expanse angle varying device and the level varying device, and a receiving device for receiving a second optical signal converted into a beam of light.

Abstract: An optical communication apparatus that includes a polarization beam splitter which synthesizes an optical axis of a light emitting optical system having a light emission element for emitting a linearly polarized light and an optical axis of a light receiving optical axis to make the optical axis for reception coincide with the optical axis for transmission. A phase plate is provided in such a manner as to be rotatable by a predetermined angle about the common axis. An optical axis of the phase plate of each of the associated communication apparatuses is set at an adequate angle before installation thereof.

Abstract: A two-way optical transmitter in which optical transmitters each having light projecting means and light receiving means on an optical axis intersecting the optical axis of the light projecting means are disposed in opposed relationship with each other with a predetermined distance interposed therebetween and which effects two-way optical transmission, wherein a polarizing beam splitter, having a cemented surface forming a certain angle with respect to the optical axes of the light projecting means and the light receiving means is installed near the point of intersection between the two optical axes, linearly polarized light from the light projecting means is reflected by the cemented surface of the polarizing beam splitter to thereby provide transmission light, and an optical axis leading from the polarizing beam splitter to the light projecting means or an optical axis leading from the polarizing beam splitter to the light receiving means is set at an angle of approximately 45.degree.