NOVA-ASTRON has delivered a suite of cryogenic astronomical instruments for large ground based telescopes as well as space missions. The instruments include polarimeters, spectrometers, cameras and interferometers, mostly operating at infrared. Several methods have been developed to verify or measure, under cryogenic conditions, the performance of optical components, coatings and complete optical systems. The test and verification setups presented in this paper include wave front error measurements, alignment inspection, spectral measurements, material properties determination and varying gravity orientation capabilities (gravity load vector). The measurement principles are explained, together with the most important error contributions and the achieved accuracies.