Spectral imaging of microscopic samples with high-performance CCD array-based spectrometer

The need for parallel spectral analysis of small details in microscopic samples is well recognized in many research fields. Many instruments were proposed for this purpose, some of them using direct projection of an image produced by a standard microscope onto entrance slit of a spectrometer. Typical scanning wavelength spectrometers using focusing reflective gratings have limited imaging performance. These spectrometers also suffer from low light coupling efficiency, poor spatial and spectral resolution, high acquisition times and low image quality. These significant concerns are now addressed by a coupling of a high performance imaging spectrometer to one of the readout ports of a microscope. This spectrometer uses refractive optics, transmission based volume phase holographic (VPH) diffraction gratings and is equipped with two-dimensional array of photodetectors. Such a system provides a significant advantage over most currently used microscope coupled spectrometers, resulting in a larger volume of extracted information, better spectral and spatial resolution, higher SNR and generally better image quality. This is illustrated with examples of spectral images of various biological samples.