Method for measuring complex degree of coherence of random optical field by using mutual intensity-intensity correlation

A method for measuring a complex degree of coherence of a random optical field by using a mutual intensity-intensity correlation, comprising steps of:

• building a test optical path comprising a quarter-wave plate, a beam splitter, a condensing element, and a light detector, using a laser as reference light, wherein the reference light is modulated by the quarter-wave plate and then enters the beam splitter, and to-be-tested light enters the beam splitter at the same time, the beam splitter combines the modulated reference light and the to-be-tested light to obtain combined light, and the combined light passes through the condensing element to be imaged on the light detector;
• rotating the quarter-wave plate to enable the fast axis of the quarter-wave plate to be consistent with a polarization direction of the reference light to obtain first combined light, and photographing and recording light intensity distribution information IS(1)(r) of the first combined light by using the light detector;
• rotating the quarter-wave plate to enable the slow axis of the quarter-wave plate to be consistent with the polarization direction of the reference light to obtain second combined light, and photographing and recording light intensity distribution information IS(2)(r) of the second combined light by using the light detector;
• blocking the reference light, and photographing and recording light intensity distribution information I(r) of the to-be-tested light by using the light detector;
• blocking the to-be-tested light, and photographing and recording light intensity distribution information Sr(r) of the reference light by using the light detector;
• and
• calculating the amplitude and phase of a complex degree of coherence of the to-be-tested light.