Improving the imaging speed of 1064  nm dispersive Raman microscopy with multifocal patterned detection

We demonstrate the compatibility of a Hadamard-coded multifocal array approach with a 1064 nm dispersive Raman microscope for improving the imaging speed. The system uses a galvomirror to generate a one-dimensional (1-D) multifocal array at the sample, and the Raman signals from the multiple foci are simultaneously detected by an InGaAs linear detector array. The superimposed spectra are deconvolved to retrieve the individual spectra at each focus. Using a silicon wafer as a test sample, we demonstrate that the method is ideal for the high noise detection conditions encountered when using 1064 nm excitation, InGaAs detectors, and high readout rates. An improvement in the imaging speed by as much as 14 times is achieved with this multifocal method.