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Measuring Specular Reflection from Multilayer Structures

IP.com Disclosure Number: IPCOM000045281D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Minn, A: AUTHOR [+2]

Abstract

Measuring the specular reflection from a surface involves reflecting a small (=1 mm) collimated light beam off the surface and detecting the amount of reflected light with a photo detector having an aperture adjusted to the diameter of the incident beam. Also, the detector must be positioned so that it Intercepts the reflected light at the same angle as the incident beam. Both incident beam and detected reflected beam must be in the same plane which is perpendicular to the surface being measured. Because of these restrictions, the angle of incidence/ reflection is normally 5 degrees to 80 degrees.

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Measuring Specular Reflection from Multilayer Structures

Measuring the specular reflection from a surface involves reflecting a small (=1 mm) collimated light beam off the surface and detecting the amount of reflected light with a photo detector having an aperture adjusted to the diameter of the incident beam. Also, the detector must be positioned so that it Intercepts the reflected light at the same angle as the incident beam. Both incident beam and detected reflected beam must be in the same plane which is perpendicular to the surface being measured. Because of these restrictions, the angle of incidence/ reflection is normally 5 degrees to 80 degrees.

The conventional method for measuring specular reflection is suitable for structures having a single reflective surface. For multilayer structures, there will be more than one reflected beam depending on the number of layers and the thickness between the layers. In a plasma display, for example, there are specular reflections from the front surface, metallurgy, dielectric/gas interfaces, and rear surface. Since the display is approximately 1.25 cm thick, there will be multiple reflected beams at the same angle as the incident beam but in different spatial locations, and accurate measure of the total specular reflection from the display requires the summation of all specularly reflected beams. The detector must therefore scan the reflected beams while maintaining the correct geometrical relationship to the incident beam.

The measurement of specular reflection from a multilayer structure can...