A 10⁻⁹-order point source transmission test facility

In order to achieve the quantitative evaluation of the stray light attenuation in optical systems, we demonstrated a point source transmission test facility with 10⁻⁹-order sensitivity in this paper. We employed a pulsed source and measured the pulse to obtain the weak signal at the image plane, as well as to simplify the detection system. Using this scheme, we constructed a test facility with a maximum aperture of 600 mm and a test wavelength of 527 nm, and conducted the test with a 250 mm aperture optical system. Experimental results showed that the point transmission at a 60-degree incident angle is 1.68×10⁻⁹. The results prove that the test error of this facility is in the order of 10⁻⁹ or below, and the test facility has the ability to test 10⁻⁹-order point source transmissions. This technology can provide quantitative evaluation for various optical systems with strict stray light requirements, like astronomical telescopes, star sensors and spaced target monitor payloads.