Spectrometers > Applications > Hyperspectral Spectroscopy
Some spectroscopic applications require the ability to construct an image of an object at multiple wavelengths. This means that for each point of the object, there exists a set of spectral information. Typically, such hyperspectral images are obtained by taking subsequent images of the object under different bandwidth illumination, with multiple detectors or with filters inserted before the detector. Acoustic filters, liquid crystal filters, filter wheels have all been used for this purpose.
P&P Optica has developed hyperspectral spectrometers which can be used to obtain very high spectral resolution hyperspectral images without the use of filters. This means that a much finer spectral resolution can be obtained within a single scan. More importantly, the entire spectrum for each point of the object is obtained simultaneously so that spectral information is not distorted by dynamically changing objects
The above figure shows absorption images for a grain of pollen at several wavelengths. The original microscope image is shown for comparison purposes
How does a hyperspectral spectrometer work?
An illustration showing hyperspectral cube obtained from imaging a grain of pollen. Multiple wavelength images are shown together with corresponding slices of spectral information. The data set is 128x128x1044 measurements.
To form a hyperspectral data set for each data acquisition, a portion of the object's image is projected onto the entrance slit of the spectrometer. The image from the slit then undergoes diffraction, and for each point along the slit, spectral information is recorded on a 2D detector array. A subsequent slit image is obtained in the next scan. Repeating this process allows us to build a three dimensional image of the object, with one dimension corresponding to signals at multiple wavelengths.
Illustration of hyperspectral image formation. Each point of an microscope image has a corresponding spectrum. Many spectra are collected simultaneously for a line along the image. Multiple acquisitions are performed to collect the entire data set.
