Infrared residual reflectivity spectrum test accessory and infrared residual reflectivity spectrum test method

The invention belongs to the technical field of reflectivity spectrum measurement, and specifically relates to an infrared residual reflectivity spectrum test accessory and an infrared residual reflectivity spectrum test method. According to the special infrared residual reflectivity spectrum test accessory designed by the invention, a reflectivity measurement optical circuit needing to be reflected twice on a tested sample is converted into a reflectivity measurement optical circuit needing to be reflected once on the test sample to measure the residual reflectivity spectrum of an antireflection film. By adopting the test method, the measurement accuracy of low-reflectivity spectra can be significantly improved, and the effect is more obvious in residual reflectivity spectrum measurement of antireflection films. The scheme has no limit on the size of tested samples, and large-size samples can be tested.