The article presents the design, fabrication, and performance evaluation of an ultra-low-reflectance calibration target for infrared wavelength instruments operating at cryogenic temperatures. These targets are essential for accurately calibrating optical systems in astrophysics, spectroscopy, and space instrumentation, where minimizing background signal and mimicking blackbody radiation are critical.

A major focus of the study is on selecting and validating appropriate black coating materials that can perform reliably at cryogenic temperatures. Among the tested materials, Acktar’s Fractal Black was applied to aluminum array structures and compared with alternatives like Gold Black and Aeroglaze Z306. The results show that Acktar’s coating achieves extremely low reflectance, when the lowest is 0.001 below 15K. The coatings function as a black body emitter in the IR range effectively.

The ultra black surface of Acktar, expect of providing high emissivity across wide spectral bands is also maintaining physical and optical integrity during the thermal cycle, which makes Acktar’s contribution even more significant. Moreover, the uniform thickness and the strong adhesion to the contours over sharp geometries, make it extra valuable for space borne and lab IR systems.

Acktar’s super black coating together with the wedge geometry contributed significantly to reduction of the scattered light while allowing the creation of compact and reliable calibration targets. Therefore, it can be said that the Acktar is a leading supplier of high-performance IR coating for cryogenic applications

J. Wollack, R. E. Kinzer, S. A. Rinehart; A cryogenic infrared calibration target. Rev. Sci. Instrum.1 April 2014; 85 (4): 044707.