Browse Prior Art Database

Indicator

IP.com Disclosure Number: IPCOM000098362D
Original Publication Date: 1960-Aug-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Schwartz, RS: AUTHOR [+2]

Abstract

An indicator device is realized, based upon the fact that the absorption edge of a material such as cadmium sulfide may be caused to vary from one wave length to another by varying the temperature of the crystal.

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Indicator

An indicator device is realized, based upon the fact that the absorption edge of a material such as cadmium sulfide may be caused to vary from one wave length to another by varying the temperature of the crystal.

A monochromatic light source 10 is directed through a transparent substrate 11, such as glass, toward a detection position 12. Mounted on the substrate 11 is a transparent, low thermal inertia heater element 13 such as Nesa glass which is conductive. By application of a signal 14, element 13 is caused to conduct and its temperature is raised. A cadmium sulfide layer 15 approximately one eighth inch thick is mounted on the heater element 13.

The light 10 is chosen to have a wave length represented by the line 16. This wave length is chosen to place it just above the absorption edge 17 of the cadmium sulfide at a steady state temperature of the crystal. As the crystal is heated in response to the signal 14, the absorption edge shifts to the position 18 and the light of wave length 16 becomes visible through the crystal. Removal of the signal 14 returns the absorption edge to the line 17. It is therefore possible to detect the presence or absence of a signal applied to the heater element 13.

The shift in the absorption edge is approximately 50 angstroms for ten degree change in temperature. Response time of the system is dictated by the thickness and thermal inertia of the heater element. A thickness of about one eighth inch gives a response time...