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US 7,397,570 B2Granted
Interferometer and shape measuring method
AssigneeMitutoyo Corporation
InventorsKazuhiko Kawasaki, Yoshimasa Suzuki, David W. Sesko
Life of this patent
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Abstract
A wavelength-variable light source is configured to emit a light with a wavelength (λ), which is variable within a scan width (Δλ). An interferometer has a coherent length (ΔL), which is determinable from (Δλ) and (λ). A controller determines an appropriate magnitude of the scan width (Δλ) while a CCD camera captures a fringe image in an exposure time (Te), which is set longer than a time for wavelength scanning.
Claims18
An interferometer, comprising:
- a wavelength-variable light source configured to emit a light with a variable wavelength;
- a light splitting/synthesizing member operative to split the light from the wavelength-variable light source into a measurement light to be led to a measuring object and a reference light to be led to a reference surface, and to synthesize the reference light reflected from the reference surface and the measurement light reflected from the measuring object to provide a synthesized light;
- an imaging unit operative to image an interference fringe image formed of the synthesized light in a certain exposure time;
- a controller operative to control the wavelength-variable light source to vary the wavelength of the emitted light within a certain wavelength range in the certain exposure time;
- and
- a shape computation unit operative to analyze the interference fringe image integrated in relation to the variations in wavelength within the certain wavelength range to compute the shape of the measuring object;
- characterized in that the wavelength-variable light source is operative to vary the center wavelength of the emitted light in a periodic function, and the imaging unit performs selective integrating reception of light in a partial time zone within one period of the periodic function.
4 more elements
A shape measuring method, comprising:
- emitting a light while giving variations in wavelength;
- splitting the light into a measurement light to be led to a measuring object and a reference light to be led to a reference surface;
- synthesizing the reference light reflected from the reference surface and the measurement light reflected from the measuring object to provide a synthesized light;
- imaging an interference fringe image formed of the synthesized light in a certain exposure time;
- controlling the wavelength-variable light source to vary the wavelength of the emitted light within a certain wavelength range in the certain exposure time;
- and
- analyzing the interference fringe image integrated in relation to the variations in wavelength within the certain wavelength range to compute the shape of the measuring object;
- characterized in that the light emitted while giving variations in wavelength is subjected to selective integrating reception of light in a partial time zone within one period of a periodic function by the imaging unit while the center wavelength of the light is varied in the periodic function.
5 more elements
Dependencies are inferred from the claim text.