Hyperspectral Spectroscopy
Hyperspectral spectroscopy builds a hyper-cube of information containing both spatial and spectral data regarding a scene. Typically, such hyperspectral cubes are obtained by taking subsequent images of the object under different bandwidth illumination, with multiple detectors or with filters inserted before the detector. Additionally, acoustic filters, liquid crystal filters and filter wheels have also been used for this purpose.
The introduction of P&P Optica’s non-scanning, high performance spectrometers based on gel gratings now allows for the acquisition of high spatial resolution and high spectral resolution hyperspectral images without the use of filters. More importantly, the entire spectra for all points of the object are obtained simultaneously so that neither spectral nor optical information is distorted by dynamically changing objects.
The patented transmission based design permits P&P Optica spectrometers to distinguish up to 200 separate spatial points arranged in any configuration. To achieve this, a large two-dimensional detector is used to register both spatial and spectral information in a single snapshot.
A fiber optic bundle is used to carry light from the image plane to the entrance slit of the spectrometer. Each point from the image plane is then registered at a separate vertical location on the detector as its spectral information is registered on the horizontal axis.
The entire hyperspectral data set is acquired in a single exposure simultaneously for all data points. This is especially important for imaging dynamically changing systems.
The patented P&P Optica design provides very low aberrations so that the entire 25 mm x 12 mm field of view (FOV) has almost no smile effect and is spot-size limited to about 10 microns.
The ability to detect even very low levels of photons allow P&P Optica spectrometers to measure exceptionally small changes within processes and to detect the presence of minute concentrations of compounds.
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In order to detect small differences between spectra, the spectrometer has to be not only sensitive but has to prevent any noisy photons from reaching the detector. P&P Optica’s patented design and gel gratings prevent most of the interference in the signal caused by scattered photons.
Depending on the spectrometer model, up to 1000 spectral points (2000 pixels) can be resolved for a single spatial coordinate.
The same approach as described here can be used for Raman imaging.
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Spectral Bandwidth |
250 nm – 2500 nm |
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Absolute diffraction grating efficiency |
Peak: >95%, average: 70-90%; depending on bandwidth size |
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Stray light |
<1x10-5 or 0.001% |
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Dispersion (nm/pixel) |
< 0.025, camera dependent |
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Spectral Resolution (nm) |
<0.05, camera dependent |
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Camera option |
Andor, Princeton Instruments, Hamamatsu, Apogee and more |
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Optical input |
Fibre bundle, Camera objectives |
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Dimensions |
10 cm x 11 cm x 28 cm |
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Weight |
<3 kg |
Single Spatial Point Spectrum
