The phase film is mainly applied in the optical technology of the ridge Prism system to improve the color reduction.
Because of the optical properties of the roof prisms, the light is divided into two paths as it enters the prism, and once they are independently passed through the prism, they converge again and are imaged through the eyepiece. Because these two rays in the prism transmission there is a small light path difference, will produce a certain phase difference, because of the interference principle, a part of the intensity of the light will be enhanced, and the other part of the color of the light will be weakened, and then affect the image of color equalization and reduction. The phase correction film is applied to the ridge prism to increase the sharpness of the image and reduce the interference of the direct and reflected light. The optical phase delay of the shorter optical path is consistent with the light phase of the longer light paths.