Emissivity target having a resistive thin film heater

Abstract

An electro-optical target and test apparatus having an improved resistive heating element. The resistive heating element comprises a resistive thin film coating layer, such as an indium tin oxide resistive coating layer, a resistive thin film semiconductor coating layer, or an electrically resistive polymer layer, that is disposed on a back side of a substrate. The substrate has a target pattern disposed on its front surface that to provide an emissivity target. The resistive coating layer provides a means for heating the substrate which produces a uniform source of thermal radiation because it has no holes therein. The resistive heating element is heated to radiate at a controlled target temperature set by a temperature controller coupled thereto. The materials comprising the coating layer and substrate may be transparent to visible and near infrared radiation. This allows radiation from visible and near infrared components of the system under test to pass through the substrate and resistive heating element to detector(s) located behind the heating element without requiring holes in the emissivity target. Also, use of a transparent substrate and heating element allows the use of visible and/or infrared light sources disposed behind the heating element, and thus the electro-optical target can simultaneously radiate both visible and infrared radiation at the system under test.