Design of novel equivalent static wedge

Existing static wedge interferometer can not achieve zero optical path difference, and it requires a strict spatial coherence of light, thereby affecting the accuracy and complexity of spectral inversion. Therefore, a novel equivalent static wedge was proposed. It consists of two different refractive index material, and two reflective surfaces perfectly vertical. Because interference of two beams of light is derived from a beam of light, it is not strictly required about spatial coherence. Moreover, it contains zero optical path difference. By deducing and analyzing the optical path difference of the arbitrary wedge position, the formula of spectral inversion was deduced. Then the wedge was designed and processed by using two materials which were different refractive index, and its maximum optical path difference could reach 168.3 m. And the process of spectral inversion was simulated. Combining maximum optical path difference with the measured spectral band, the requirement of the linear CCD pixel count was analyzed. The wedge was analyzed by experiments which use 532 nm and 632.8 nm lasers. The results show that the spectral inversion center wavelength error is less than 0.2%.