Siau-Way Liew

Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Electrical Engineering


The gain response of the detectors in the cold focal plane of the Landsat 4 ad 5 Thematic Mapper (TM) is known to fluctuate temporally. This is believed to be caused by an interference effect due to a film build-up on the cold focal plane dewar window. This paper analyzes the effect using a thin-film interference model. This model relates detector gain to film thickness through indices of refraction of the materials involved The dewar window material is Zinc Selenide (ZnSe) a known index of refraction, thus the index of refraction of the film in TM Band 5 and Band 7 can be determined by fitting the model to - the gain data from each detector The film is found to be absorptive in Band 7, but this is not apparent in Band 5. Film thickness has been determined to be as much as 1400nm from the data sample used. This model is also used to remove gain variation for gain characterization over instrument lifetime. An accurate model of this effect can improve the calibration of Landsat 4 and 5 by three to four percent in Bad 5 and Band 7. It is also applicable to the Landsat 7 Enhanced Thematic Plus (ETM+) if this thin film build-up is present.

Library of Congress Subject Headings

Landsat satellites -- Calibration Artificial satellites in remote sensing -- Calibration



Number of Pages



South Dakota State University