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Browse Prior Art Database

Dip Probe for Paint Colorimeter

IP.com Disclosure Number: IPCOM000085086D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Horchos, LA: AUTHOR [+2]

Abstract

One of the basic problems in the design of a colorimeter head, is to discriminate between specular and diffuse light returned from the colored specimen. The reason for the discrimination is that specular light contains essentially no information about the color of the specimen--the color of this light being substantially that of the source. The diffusely scattered light has interacted with the specimen in depth and its color is determined by both the source and the specimen. It is this diffusely scattered light that is to be analyzed in the colorimeter.

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Dip Probe for Paint Colorimeter

One of the basic problems in the design of a colorimeter head, is to discriminate between specular and diffuse light returned from the colored specimen. The reason for the discrimination is that specular light contains essentially no information about the color of the specimen--the color of this light being substantially that of the source. The diffusely scattered light has interacted with the specimen in depth and its color is determined by both the source and the specimen. It is this diffusely scattered light that is to be analyzed in the colorimeter.

In the design of colorimeter sensing heads various schemes are used to reject specular light and detect only diffusely scattered light. These involve carefully selected angles of illumination and viewing, use of various configurations of integrating spheres, use of polarizing filters, etc.

The drawing shows various probes using the principle that specular reflection is a surface or interface phenomena, which occurs only when light passes from a medium of one index of refraction to a medium of a different index of refraction. If there is no change in index or refraction in going from one medium to another, there can be no specular reflection. Many common paint vehicles have an index of refraction in the range of 1.48 to 1.52. By making the probes of ordinary glass having an index of refraction of about 1.50, such probes provide a satisfactory match to eliminate or greatly reduce the...