Browse Prior Art Database

Diffuse Reflectance Measurement Technique

IP.com Disclosure Number: IPCOM000085875D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Paladini, AW: AUTHOR [+2]

Abstract

Color matching of textiles and paints using the well-known "Kubelka Munk" theory requires measurement of diffuse reflectance. Such a measurement may be obtained by a spectrophotometer having a measuring head that is positioned next to a test sample. A small area of the sample is illuminated and light reflected therefrom is collected and analyzed. The head includes an internal chamber the walls of which may be blackened to provide low reflectivity.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Diffuse Reflectance Measurement Technique

Color matching of textiles and paints using the well-known "Kubelka Munk" theory requires measurement of diffuse reflectance. Such a measurement may be obtained by a spectrophotometer having a measuring head that is positioned next to a test sample. A small area of the sample is illuminated and light reflected therefrom is collected and analyzed. The head includes an internal chamber the walls of which may be blackened to provide low reflectivity.

In accordance with the technique, the reflectivity R(M) a specular surface, simulating (as described below) the finish of the material to be measured, is made. From the measured reflectivity R(M), the specular reflectivity R(SP) can be calculated in accordance with the following equation: R(SP) = R(M) (1 + A(W) R(W) over 1 + A(S) R(M) where; R(W) is the wall reflectivity. A(W) is the fraction of the internal area which is wall. A(S) is the fraction of the internal area which is sample. A(S) + A(W) = 1.

Next, the reflectivity R(MS) is measured from the actual sample of interest and the diffuse reflectivity R(D) thereof may be calculated in accordance with the following formula: R(D) = R(MS) - A(S) R(MS) R(SP) - A(W) R(MS) R(W) over 1 + A(S) R(MS)

This measurement technique requires simulation of an ordered pure specular surface. Such a surface is different in character from a plain mirror in that the return flux, while specular, is randomly oriented so as to take on all directional vectors within the measuring head. One means of accomplish...