Abstract: An optical deflector comprises a control means for controlling at least either a light source or a deflection means adapted to gauge the distance between the position of a deflected beam of light moving on a light receiving element in one direction and the position of another deflected beam of light moving on the light receiving element in the opposite direction and control the distance so as to make it agree with a predetermined value. Thus, the optical deflector can very accurately control the operation of the deflection means in such a way that it is not affected by changes of environmental temperature of the deflection means and the detection circuit, because a detection means for detecting the time when a beam of light passes by a predetermined angle of deflection of the deflection means is not used.

Abstract: An optical deflector comprises a control means for controlling at least either a light source or a deflection means adapted to gauge the distance between the position of a deflected beam of light moving on a light receiving element in one direction and the position of another deflected beam of light moving on the light receiving element in the opposite direction and control the distance so as to make it agree with a predetermined value. Thus, the optical deflector can very accurately control the operation of the deflection means in such a way that it is not affected by changes of environmental temperature of the deflection means and the detection circuit, because a detection means for detecting the time when a beam of light passes by a predetermined angle of deflection of the deflection means is not used.

Abstract: To provide a small-size oscillating device, a coil is disposed on a substrate.

Abstract: To provide a small-size oscillating device, a coil is disposed on a substrate.

Abstract: 0 A light beam deflecting apparatus which measures the passing time of a light beam in reciprocating scans on a specified position on the scanning line, and then calculates time lag data corresponding to the time lag in the reciprocating scan of a light beam deflecting device with respect to the drive signal therefor. From a measurement of two passing times in forward and backward scans, timing data is calculated, corresponding to the modulation start or end time of the light beam within a scanning cycle period. The invention resolves the drawback, in a light beam deflecting device for displaying an image by reciprocating light beam scannings, of image variation by variations for example in amplitude, phase and offset.

Abstract: There is provided an optical deflector which has a control means for controlling deflection portion so as to deflect a deflection light beam at a desirable maximal deflection angle. According to the optical deflector, a scanning amplitude of the deflection portion can be suitably controlled by the control means.

Abstract: Provided is image display apparatus, in which a surface to be scanned is two-dimensionally scanned with a light beam which is modulated based on image information and emitted from a light source means and an image formed on the surface to be scanned is observed through an optical system, wherein a synchronization light detection device to obtain synchronization signal related to a scanning start position on the surface to be scanned is disposed on the surface to be scanned, on the vicinity thereof, or on a surface optically conjugate therewith, so that a synchronization signal can be detected with high precision and a preferable quality image can be displayed for observation, and image taking apparatus including the image display apparatus.

Abstract: An optical deflector comprises a control means for controlling at least either a light source or a deflection means adapted to gauge the distance between the position of a deflected beam of light moving on a light receiving element in one direction and the position of another deflected beam of light moving on the light receiving element in the opposite direction and control the distance so as to make it agree with a predetermined value. Thus, the optical deflector can very accurately control the operation of the deflection means in such a way that it is not affected by changes of environmental temperature of the deflection means and the detection circuit, because a detection means for detecting the time when a beam of light passes by a predetermined angle of deflection of the deflection means is not used.

Abstract: A two-dimensional image is displayed by causing a light beam scanning in a horizontal direction x to also scan in a vertical direction y. First photo-detector P is arranged in a region where the scan speed of the light beam in the first direction x is highest and the scan speed of the light beam in the second direction y is lowest, whereas second photo-detector Q is arranged in a region where the scan speed of the light beam in the second direction y is highest and the scan speed of the light beam in the first direction x is lowest so that both of the photo-detectors can accurately detect the scan timing of the light beam. Any possible error of synchronism of the horizontal scan of the light beam and the vertical scan of the light beam can be prevented by using the signals from the photo-detectors P, Q.

Abstract: To provide a small-size oscillating device, a coil is disposed on a substrate.

Abstract: The invention resolves the drawback, in a light beam deflecting device for displaying an image by reciprocating light beam scannings, of image variation by variations for example in amplitude, phase and offset.

Abstract: A two-dimensional image is displayed by causing a light beam scanning in a horizontal direction x to also scan in a vertical direction y. First photo-detector P is arranged in a region where the scan speed of the light beam in the first direction x is highest and the scan speed of the light beam in the second direction y is lowest, whereas second photo-detector Q is arranged in a region where the scan speed of the light beam in the second direction y is highest and the scan speed of the light beam in the first direction x is lowest so that both of the photo-detectors can accurately detect the scan timing of the light beam. Any possible error of synchronism of the horizontal scan of the light beam and the vertical scan of the light beam can be prevented by using the signals from the photo-detectors P, Q.

Abstract: In a wavelength locking method, and in an apparatus and a network system using the method, a wavelength of a tunable filter is caused to track a wavelength of light from a light source by controlling a control signal by controlling an operation condition of the tunable filter in a feedback control system of a wavelength locking system. According to the method, an error signal relevant to a deviation of the wavelength of the tunable filter from the wavelength of the light source is generated, an operation signal for feedback control of the wavelength locking system is generated by using the error signal, the operation signal is detected, and a bias component of the control signal is corrected or renewed based on the detected operation signal such that an absolute value of the operation signal does not exceed a predetermined value.

Abstract: In a wavelength-changeable light source of the present invention, a wavelength control is performed using a plurality of control systems when the wavelength of a laser, particularly a semiconductor laser, is to be controlled. Wavelength control characteristics of the respective control systems are different from each other, and the wavelength control can be flexibly carried out by combining those characteristics. Specifically, one of the plural control systems is a current control unit for controlling a current supplied to the semiconductor laser and another thereof is a temperature control unit for controlling temperature of the semiconductor laser. In the structure, the wavelength shift with a speedy response time, which can be attained in a wavelenth-changeable range obtainable by the current control, can be carried out over a wide wavelength-changeable range obtainable by the temperature control.

Abstract: A method of controlling a wavelength of emitted light in a network system having a light transmission line for transmitting light, light-emitting means having a plurality of discrete continuous-wavelength-tunable ranges and emitting the light to the light transmission line, and detecting means for detecting light on the light transmission line, includes detecting, by the detecting means, a wavelength falling within one of the plurality of continuous-wavelength-tunable ranges of the light-emitting means which does not interfere with any wavelengths of light being transmitted on the light transmission line, and emitting, to the light transmission line, light from the light-emitting means at the wavelength detected in said detecting step.

Abstract: A driving method of the present invention drives a semiconductor laser which is provided with at least first and second electrodes through each of which current is injected into the semiconductor laser. Varying current is injected through the first electrode when the frequency of the varying current is in a high frequency band. Varying current is injected through the first electrode while phase-shifted current, whose phase is shifted relative to the varying current, is injected through the second electrode, when the frequency of the varying current is in a low frequency band which is lower than the frequency of the high frequency band. Feedback-control may be performed for controlling a ratio between amplitudes of the modulation current and the phase-shifted current based on a light output from the semiconductor laser.

Abstract: A wavelength control method controls a wavelength of output light from an optical transmitter used in an optical communication system for performing wavelength-multiplexing. The method includes steps of causing light-output means of the optical transmitter to output light and guiding the output light of the light-output means and light used in the optical communication system to a wavelength tunable filter. The method also includes sweeping a selective wavelength of the wavelength tunable filter, and detecting, based on the sweeping, if a wavelength spacing between a wavelength of the output light, which is output from the light-output means, and a wavelength of the light used in the optical communication system, which is adjacent to the wavelength of the output light on a wavelength axis on either a longer wavelength side or a shorter wavelength side, is wider or narrower than a predetermined wavelength spacing.

Abstract: In an optical communication system for performing wavelength division multiplex communication on an optical transmission path, an output light wavelength control is performed as follows in an optical transmitter. A wavelength of light on the optical transmission path is detected so as to search for an unoccupied space, in which output light from the self optical transmitter does not cause an interference with another light on the optical transmission path. The wavelength of the output light from the self optical transmitter is controlled so as to be a wavelength falling within the unoccupied space.

Abstract: A variable wavelength light source is provided with a laser of which the oscillating state can be changed over between two oscillating states accompanied by a change of an oscillation wavelength, and an optical selection element for selecting an output light in one of the two oscillating states of the laser. The optical selection element is capable of changing over which of the output lights in the two oscillating states of the laser is to be selected. Also, by using a laser in which the oscillation wavelength in the respective oscillating states can be changed, the wavelength variation ranges in the both oscillating states can be used.

Abstract: This invention discloses the following. Two modulation currents are injected into different electrodes of a semiconductor laser having a plurality of electrodes. The relationship between the phases of the two modulation currents is so adjusted that an output waveform is not distorted especially when a modulation frequency is low. Polarization modulation is applied as the modulation form.