Optical thickness measuring apparatus

• US 5,056,923 A
• Filed: 02/14/1991
• Issued: 10/15/1991
• Est. Priority Date: 06/29/1988
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Matsushita, Toshihiro, Ebisawa, Ryoji
• Primary Examiner(s): Evans, F. L.
• Application Number:
  US07/655,020
• Time in Patent Office: 243 Days
• Field of Search: 356/381, 356/382, 356/405
• US Class Current: 356/632
• CPC Class Codes: G01B 11/0625 with measurement of absorption or reflection

Abstract

An optical thickness measuring apparatus comprises a light source, a spectral device which separates light produced by the light source into its spectral components, and a photodetector for detecting the light which has been separated by the spectral device into its spectral components and which has been scatter-reflected by a material being subjected to thickness measurement, said photodetector receiving only scatter-reflected light. An operation processing device calculates either one of variables a* or b* of an L*a*b* colorimetric system or either one of variable u* or v* of an L*u*v* colorimetric system on the basis of information about the light which has been scatter-reflected by the material. The information is received from the photodetector. A thickness calculating device calculates the thickness of the material from the value of the variable calculated by the operation processing device.

Claims

1. An optical thickness measuring apparatus which comprises:

i) a light source,

ii) a spectral means which separates light produced by said light source into its spectral components,

iii) a photo detecting means for detecting the light which has been separated by said spectral means into its spectral components and which has been scatter-reflected by a material being subjected to thickness measurement, said photo detecting means receiving only scatter-reflected light,

iv) an operation processing means which calculates either one of variables a^* or b^* of an L^* a^* b^* colorimetric system or either one of variables u^* or v^* of an L^* u^* v^* colorimetric system on the basis of information about the light which has been scatter-reflected by said material, said information being received from said photo detecting means, and

v) a thickness calculating means which calculates the thickness of said material from the value of the variable calculated by said operation processing means.

2. An optical thickness measuring apparatus which comprises:

i) a light source which irradiates light to a material, the thickness of which is to be measured,

ii) a spectral means for separating the light, which has been scatter-reflected by said material, into its spectral components,

iii) a photo detecting means for detecting the light which has been scatter-reflected by said material, and which has been separated by said spectral means into the spectral components, said photo detecting means receiving only scatter-reflected light.

iv) an operation processing means which calculates either one of variables a^* or b^* of an L^* a^* b^* colorimetric system or either one of variables u^* or v^* of an L^* u^* v^* colorimetric system on the basis of information about the light which has been scatter-reflected by said material, said information being received from said photo detecting means, and

v) a thickness calculating means which calculates the thickness of said material from the value of the variable calculated by said operation processing means.