Abstract: A method and apparatus for photon counting are disclosed. In an implementation, the present disclosure provides a dynamic-range photon-counting spectrometric sensor for low signal detection embedded in large parasitic background light signal. Rather than using a known forward illuminated imager approach of counting photons directly, embodiments of the present disclosure use a backward illuminated imager approach to generate a burst of electrons based on the photons, and perform photon detection by counting the generated burst of electrons using the plurality of CMOS chip pixels. An electronic circuit, in communication with the CMOS chip pixels, includes a fast clock enabling discrimination between electrons in time. The electronic circuit can be built on the face of a semiconductor wafer on which the CMOS chip pixels are provided.

Abstract: A man portable device for detecting the presence of hazardous material includes a pulsed or time-modulated light source and an objective scannable across the surface of a sample for projecting light from the light source onto a succession of spots on the surface of the sample. A spectrometer performs a spectral analysis of the induced fluorescence to create a first dataset defining a first vector as a function of wavelength. A time domain detector for measuring the time decay of the induced fluorescence collected simultaneously creates a second dataset defining a second vector as a function of time. A computer identifies hazardous material by performing independent multivariate analysis on the first and second vectors as the objective is scanned across the sample surface based on fluorescent signal models for hazardous materials in the spectral and time domains.