Accession Number:

ADA114571

Title:

The Influence of the Temperature Coefficient of Refractive Index on a Thermal Imager.

Descriptive Note:

Memorandum rept.,

Corporate Author:

ROYAL SIGNALS AND RADAR ESTABLISHMENT MALVERN (ENGLAND)

Personal Author(s):

• Carmichael,I. C.

Report Date:

1981-01-01

Pagination or Media Count:

34.0

Abstract:

The temperature coefficient of refractive index for germanium was determined in the 8-12 micrometers and 3-5 micrometers wavebands. The Strehl intensity ratio and frequency response of an optical system are related to a lens temperature changes, and a simple factor for a comparison of different lens materials is included. The relative change in minimum resolvable temperature difference MRTD of a thermal imaging system is shown for a defocused optical system, where the defocus is related to a lens temperature change. It is shown that the criterion for a good optical performance may be applied to the relative change in MRTD for a thermal imager, and that the Marechal approximation to the Strehl ratio may be used to determine a tolerance upon a change in lens temperature. Author

Descriptors:

• *REFRACTIVE INDEX
• *GERMANIUM
• *LENSES
• *INFRARED EQUIPMENT
• *TEMPERATURE COEFFICIENTS
• MATERIALS
• OPTICAL PROPERTIES
• INTERMEDIATE INFRARED RADIATION
• INFRARED IMAGES
• FAR INFRARED RADIATION
• INTENSITY
• FREQUENCY RESPONSE
• TEMPERATURE
• RATIOS
• UNITED KINGDOM

Subject Categories:

• Optics
• Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE