Method and device for microscopic imaging based on frequency-domain modulation

A device for microscopic imaging based on frequency-domain modulation, comprising:

• a laser device configured to emit a high-power laser and a low-power laser;
• a glan prism configured to change polarization states of the high-power laser and the low-power laser emitted by the laser device to obtain two beams of line-polarized light;
• an electro-optic modulator configured to modulate intensities of two beams of the line-polarized light to obtain two beams of line-polarized light with different preset frequencies;
• a 0˜2π vortex phase plate configured to perform phase modulation of the high-power laser;
• a quarter-wave plate configured to change polarization states of the two beams of line-polarized light with different preset frequencies to obtain two beams of right-handed circularly polarized light;
• a dichroic mirror configured to combine one beam of right-handed circularly polarized light corresponding to the low-power laser and another beam of right-handed circularly polarized light corresponding to the high-power laser after phase modulation into a single beam of right-handed circularly polarized light;
• a galvanometer scanner configured to deflect an optical path of the single beam of right-handed circularly polarized light;
• a scanning lens and a field lens configured to focus and collimate the single beam of right-handed circularly polarized light emitted from the galvanometer scanner;
• a microscope objective configured to project the single beam of right-handed circularly polarized light emitted from the field lens onto a sample to be measured;
• a detection module configured to collect signal light emitted by the sample to be measured;
• and
• a lock-in amplifier configured to demodulate the received signal light at a specific frequency to obtain an image at a corresponding scanning position, wherein
• the detection module includes a beam splitter, a bandpass filter, a detector, a collection lens, and a spatial filter, wherein
• the beam splitter is arranged between the 0˜2π vortex phase plate and the galvanometer scanner,
• the bandpass filter is configured to filter out stray light of a signal beam emitted from the beam splitter,
• the collection lens is configured to focus the filtered signal beam onto the detector,
• the spatial filter is disposed at a focal plane of the collection lens, and is configured to spatially filter the filtered signal beam, and
• the detector is configured to detect a light intensity signal of the filtered signal beam.