Laser scanning microscope with electrical high-order modulation extraction module

An electrical high-order modulation extraction module, used to receive the RF sinusoidal signal output by a photodetector on a laser scanning microscope with a laser scanning frequency, wherein the electrical high-order modulation extraction module includes:

• a DC blocking filter used to filter out the DC signal on the RF sinusoidal signal output by the photodetector;
• a first splitter used to split the RF sinusoidal signal that has passed through the DC blocking filter into a first optical path and a second optical path;
• a function generator used to provide a local oscillation frequency, wherein the local oscillation frequency is an integer multiple of the laser scanning frequency;
• a second splitter used to split the local oscillation frequency into a quadrature path and an in-phase path;
• a first mixer, one input end of the first mixer receives the sinusoidal signal of the first optical path, and the other input end receives the quadrature path, and outputs a first intermediate frequency signal, wherein the first intermediate frequency signal is used to down-modulate the first-order modulation (1M) signal to the DC coordinate position;
• and
• a second mixer, one input end of the second mixer receives the sinusoidal signal of the second optical path, and the other input end receives the in-phase path, and outputs a second intermediate frequency signal, wherein the second intermediate frequency signal is used to down-modulate the first-order modulation (1M) signal to the DC coordinate position;
• and wherein the first intermediate frequency signal and the second intermediate frequency signal are transmitted to an arithmetic unit for calculation, and then the calculated root mean square signal is transmitted to a DAQ program for pixel reconstruction.

A method for adjusting the imaging quality of a laser scanning microscope using an electrical high-order modulation extraction module, the method comprising the following steps:

• providing a module manufactured by the electrical high-order modulation extraction module, and connecting the module with the laser scanning microscope and the servo terminal;
• obtaining and determining whether the laser repetition frequency and the LO signal frequency are the same, by obtaining the laser repetition frequency of the laser scanning microscope and the LO signal frequency generated by the function generator through the information displayed on the servo terminal, and determining whether the LO signal frequency is a multiple of the laser repetition frequency;
• correcting the LO signal frequency, by adjusting the LO signal frequency output by the function generator through the servo terminal when the LO signal frequency is not a multiple of the laser repetition frequency, so that the LO signal frequency is a multiple of the laser repetition frequency;
• providing a high-order modulation signal, by obtaining a down-modulated high-order modulation signal through the calculation of the module, and transmitting the down-modulated high-order modulation signal to the DAQ program configured in the servo terminal for pixel reconstruction;
• and
• adjusting the imaging quality, by the observer sequentially selecting a down-modulated signal (1M, 2M, 3M, . . . ), and transmitting the down-modulated signal to the DAQ, and the DAQ program sequentially performing pixel reconstruction.