Abstract: Methods and apparatus for obtaining a vibrational circular dichroism (VCD) image using a discrete frequency infrared (DFIR) microscope are disclosed. The method includes generating a pulsed laser beam comprising a spectral frequency, which may be tunable; modulating the laser beam to generate circularly polarized light; illuminating a sample and collecting, and detecting an optical signal transmitted or transflected from the location of the sample. The detected signal is demodulated at, for example, both the pulse frequency and the sum or difference of the pulse frequency and the modulating frequency to obtain an intensity value that correspond to the absorbance, and a polarization-dependent value that corresponds to the VCD. Other configurations of the apparatus may be employed to measure VCB and VLD.

Abstract: The disclosure is directed to methods and apparatus for obtaining a discrete frequency infrared (DFIR) spectroscopic image. The method includes generating, by a laser source, a pulsed laser beam comprising a spectral frequency in a mid-IR region and a pulse repetition rate; transmitting, by a first group of optical components, the pulsed laser beam onto a location of a sample; collecting, by a second group of optical components, an optical signal emitting from the location of the sample onto a detector to obtain a raw electric signal; demodulating, by a demodulator based on the pulse repetition rate, the raw electric signal to obtain an intensity value; and determining, by a control device and based on the intensity value, a pixel value corresponding to the spectral frequency in a DFIR spectroscopic image.

Abstract: Methods and apparatus for obtaining a vibrational circular dichroism (VCD) image using a discrete frequency infrared (DFIR) microscope are disclosed. The method includes generating a pulsed laser beam comprising a spectral frequency, which may be tunable; modulating the laser beam to generate circularly polarized light; illuminating a sample and collecting, and detecting an optical signal transmitted or transflected from the location of the sample. The detected signal is demodulated at, for example, both the pulse frequency and the sum or difference of the pulse frequency and the modulating frequency to obtain an intensity value that correspond to the absorbance, and a polarization-dependent value that corresponds to the VCD. Other configurations of the apparatus may be employed to measure VCB and VLD.

Abstract: The disclosure is directed to methods and apparatus for obtaining a discrete frequency infrared (DFIR) spectroscopic image. The method includes generating, by a laser source, a pulsed laser beam comprising a spectral frequency in a mid-IR region and a pulse repetition rate; transmitting, by a first group of optical components, the pulsed laser beam onto a location of a sample; collecting, by a second group of optical components, an optical signal emitting from the location of the sample onto a detector to obtain a raw electric signal; demodulating, by a demodulator based on the pulse repetition rate, the raw electric signal to obtain an intensity value; and determining, by a control device and based on the intensity value, a pixel value corresponding to the spectral frequency in a DFIR spectroscopic image.