Mitutoyo Corporation

Shinichi Hara

Yoshimasa Suzuki

Hiroki Ujihara

Naoyuki Taketomi

Masayuki Nara

Tomotaka Takahashi

Makoto Abbe

Shinji Komatsuzaki

Shinichirou Yanaka

Ryusuke Kato

Makoto Abe

A measurement apparatus includes a laser apparatus, a branch that branches a frequency-modulated laser beam into a reference light and a measurement light, a beat signal generator that generates a beat signal by mixing the reference light and a reflected light that is the measurement light radiated onto an object to be measured, a first analyzer that analyses a first signal component corresponding to a difference in a propagation distance between the reference light and the measurement light on the basis of the beat signal, a second analyzer that analyses a second signal component corresponding to a cavity frequency of an optical cavity on the basis of the beat signal, and calculation circuitry that calculates the difference in the propagation distance between the reference light and the measurement light.

Measurement apparatus and measurement method

A measurement apparatus includes a laser apparatus, a branching part that branches a frequency-modulated laser beam output by the laser apparatus into a reference light and a measurement light; a beat signal generation part that generates a beat signal by mixing a reflected light and the reference light, a conversion part that converts the beat signal into a digital signal at a first sampling rate and frequency-analyses it, an extraction part that extracts a signal component corresponding to a cavity frequency from the frequency-modulated laser beam, a digital filter that digitally filters the extracted signal component at a second sampling rate; and a calculation part that calculates a difference in a propagation distance between the reference light and the measurement light.

A measurement apparatus, including: a laser apparatus that outputs a frequency-modulated laser beam with a plurality of modes; a branching part that branches the frequency-modulated laser beam into a reference light and a measurement light; a beat signal generation part that generates a plurality of beat signals by mixing the reference light and a reflected light that is reflected by radiating the measurement light onto an object to be measured; a conversion part that converts the plurality of beat signals into digital signals by sampling the beat signals at a frequency greater than or equal to four times a resonator frequency of the laser resonator; and a calculation part that calculates a distance from the measurement apparatus to the object to be measured on the basis of the digital signals is provided.

Measurement apparatus and measurement method using a laser and beat signals

A laser interferometer that includes a laser interferometer, an position sensitive detector detecting an offset of an optical axis of the laser interferometer, a biaxial rotator turning the laser interferometer toward an arbitrary direction, an angle sensor detecting a rotation angle of the biaxial rotator, a retro reflector reflecting reflected light in a direction parallel to incident light, and a controller performing feedback control of the biaxial rotator so as to track the retro reflector based on signals from the position sensitive detector and the angle sensor. The tracking-type laser interferometer starts tracking control when return light from the retro reflector is returned to a detection range of the position sensitive detector, and changes gain for the feedback control in accordance with a behavior for a position of the return light on the position sensitive detector due to the tracking control.

Feedback gain adjusting method and device of tracking-type laser interferometer and tracking-type laser interferometer

A tracking-type laser interferometer in which a pattern emission control unit controls a changing mechanism such that light is emitted along a predetermined pattern when judged by a first judgment unit that at least one of received-light amounts at first and second light reception units is not greater than a first threshold value. A tracking control unit causes the changing mechanism to keep track of a retro reflector when judged by a second judgment unit that both of the received-light amounts at the first and second light reception units are greater than second threshold values during a time period in which the pattern emission control unit controls the changing mechanism for the emission of light along the pattern. The interferometer emits light along the pattern to search for the retro reflector upon losing sight thereof. Upon detection, the interferometer can keep track of the reflector again and resume measurement.

Tracking-type laser interferometer

In the tracking type laser interferometer including: a laser interferometer; an optical axis deviation detection sensor for detecting a deviation of an optical axis of the laser interferometer; a two-axis turning mechanism for turning the laser interferometer to any optional direction; an angle sensor for detecting a turning angle of the two-axis turning mechanism; a retroreflector for reflecting its reflected light to a direction parallel to the incident light; and a controller for driving the two-axis turning mechanism so as to track the retroreflector based on signals of the optical axis deviation detection sensor and the angle sensor, stop of the retroreflector is detected, and a target distance is calculated from the turning center of the laser interferometer to the center of the retroreflector based on the total sum of deviation of an optical axis during movement, which is obtained by the optical axis deviation detection sensor, and a turning angle during movement, which is obtained by the angle sensor.

Method for estimating distance between tracking type laser interferometer and target, and tracking type laser interferometer

A method for estimating an absolute distance between a tracking laser interferometer and a retroreflector is provided. The tracking laser interferometer includes the retroreflector for reflecting and returning an incident measurement light in an incident direction and a two-axis rotating mechanism for rotationally moving in an exit direction of the measurement light so that optical axes of the measurement light and return light are collimated.

Method for estimating absolute distance of tracking laser interferometer and tracking laser interferometer

A laser tracking interferometer directs a laser beam to a retroreflector serving as an object to be measured to sense a displacement of the retroreflector using interference with a laser beam back reflected from the retroreflector. The laser tracking interferometer includes: a reference sphere; a carriage that rotates about a center of the reference sphere; a laser interferometer; a displacement gage for providing a displacement signal corresponding to a relative displacement between the reference sphere and the displacement gage; a data processing apparatus for computing a displacement of the retroreflector; a position sensitive detector for providing a position signal corresponding to deviation of a laser beam; and a controller for controlling rotation of the carriage based on the position signal so that the amount of deviation becomes zero.

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Tsukuba, Japan

Shinichi Hara