a light is emitted by the laser device to reflected to the grating beam-splitter through the first reflector, and is split into a first beam of light and a second beam of light through the grating beam-splitter;

the first beam of light is reflected by the second reflector, reflected by the first universal reflector and transmitted by the first lens sequentially and propagates to the beam splitting prism, a reflected light through the beam splitting prism propagates to the angle measurement module, and a transmitted light through the beam splitting prism propagates to the third lens and is transmitted by the third lens so as to be focused on the substrate for exposure;

the second beam of light is reflected by the second universal reflector and transmitted by the second lens sequentially and propagates to the beam splitting prism, a transmitted light through the beam splitting prism propagates to the angle measurement module, and a reflected light through the beam splitting prism propagates to the third lens and is transmitted by the third lens so as to be focused on the substrate for exposure;

the angle measurement module measures angles of the first beam of light and the second beam of light input therein, and transmits a measurement finish information to the signal processing terminal, the signal processing terminal processes the measurement finish information and then transmits the processed measurement finish information to the controller, the controller generates a control command according to the received processed measurement finish information and transmits the control command to the driver, and the driver adjusts angles of the first universal reflector and the second universal reflector according to the control command, so as to change angles of the first beam of light and the second beam of light focusing and exposing onto the substrate, and form the substrate into a grating through focusing and exposing,

wherein the laser interference photolithography system further comprises a phase measurement interferometer, a third reflector, a fourth reflector, a third universal reflector, a fourth lens, a beam extracting mirror, a first phase modulator, a second phase modulator and a third phase modulator, the third universal reflector is connected with the driver, the control module further comprises a phase modulation actuator which is connected with the controller, the first phase modulator, the second phase modulator and the third phase modulator respectively, and the phase measurement interferometer is connected with the signal processing terminal;

the first phase modulator is provided between the laser device and the first reflector, a light is emitted by the laser device to divided into a zero-order diffracted light and a first-order diffracted light through the first phase modulator, the zero-order diffracted light propagates to the first reflector, and the first-order diffracted light passes through the third reflector, the fourth reflector, the third universal reflector and the fourth lens sequentially to become a third input beam of the phase measurement interferometer;

the second phase modulator is provided between the grating beam-splitter and the second reflector, and the third phase modulator is connected and provided between the grating beam-splitter and the second universal reflector;

the beam extracting mirror is provided between the beam splitting prism and the third lens, the first beam of light is reflected by the beam extracting mirror to become a second input beam of the phase measurement interferometer, and the second beam of light is reflected by the beam extracting mirror to become a first input beam of the phase measurement interferometer; and

the first input beam, the second input beam and the third input beam propagate through the phase measurement interferometer to obtain two interferometric electrical signals, the two interferometric electrical signals are transmitted to the signal processing terminal, and the two interferometric electrical signals are transmitted to the controller to perform calculation, so as to obtain a phase drift information of exposure fringes, and generate a compensation command and transmit the compensation command to the phase modulation actuator, the phase modulation actuator transmits the compensation command to the first phase modulator, the second phase modulator and the third phase modulator to perform phase modulation, so as to complete locking of a phase drift of the exposure fringes, and the driver adjusts the first universal reflector and the second universal reflector to rotate counterclockwise/clockwise, and meanwhile adjusts the third universal reflector to rotate clockwise/counterclockwise according to the control command, so as to ensure that the interferometric signals are always combined, and strengths of the interferometric signals will not be weaken correspondingly, and maintain accurate fringe control during exposure process, so as to improve interference photolithography accuracy for a large-area grating having a gradually changing period.