Vibrational circular dichroism infrared spectroscopic imaging microscope

A method for obtaining a discrete frequency infrared (DFIR) spectroscopic image for a sample, the method comprising:

• generating, by a laser source, a laser beam comprising a spectral frequency;
• modulating the laser beam in intensity or phase at a first modulation frequency;
• modulating the polarization state of the laser beam to include at least two polarization states at a second modulation frequency;
• transmitting, by a first group of optical components, the modulated pulsed laser beam onto a location of a sample;
• collecting, by a second group of optical components, optical signal transmitted or transflected from the location of the sample onto a photodetector to obtain an electric signal;
• demodulating, by a first demodulator, based on the first modulation frequency, the electric signal to obtain a first intensity value corresponding to the location of the sample;
• demodulating, by a second demodulator, based on at least the second modulation frequency, the electrical signal to obtain a second intensity value corresponding to the location of the sample;
• and
• determining, by a control device comprising a processor and a non-volatile memory, storing computer executable instructions in communication with the non-volatile memory, based on the first intensity value, a first pixel value of a DFIR spectroscopic image corresponding to the location of the sample;
• and based on at least the second intensity value, a second pixel value of a DFIR image corresponding to a same location of the sample.