Instruments and Facilities

Imaging Spectrometer

Example showing the Capability of imaging spectroscopy to rapidly map mineral compositions of outcrops, in this case at the Haughton impact structure in the Canadian High Arctic.

The Caltech imaging spectrometer system (also called a hyperspectral imager) consists of a quad-core processor and two sensors (f/2.5 aperture vertical slit cameras) co-boresighted on an optical bench. The system was custom-built by Headwall Photonics, Inc. and is field-portable.

  • Rapid, non-destructive mineral or non-mineral material mapping of samples and outcrops
  • Visible-near infrared sensor: CMOS array, 0.4-1.0 μm wavelength coverage, 5 nm spectral resolution, 1.625 nm spectral sampling
  • Shortwave infrared sensor: MCT array, 0.9-2.6 μm wavelength coverage, 6 nm spectral resolution, 6 nm sampling interval
  • Signal-to-noise ratio (SNR) >100 for all channels
  • All measurements are made relative to Spectralon®and corrected for the absolute reflectance properties of Spectralon®

This instrument was purchased through cost-sharing between a NASA Planetary Major Equipment grant, a Rose Hills Foundation grant, and internal Caltech support.

Laboratory setup (microscopic mode)


The instrument is mounted on a custom rack built by Caltech looking downward with the field of measurement illuminated by a halogen slit lamp (output manually set up to 180 W). Images are acquired by moving the sample under the instrument with a fine motion-control stage to obtain images at spatial resolutions of ~71 μm/pixel (VNIR) and ~212 μm/pixel (SWIR).

  • This instrument can acquire images over any stage or track that moves samples at a constant rate up to a few cm/s for offsite applications. We have experience interfacing with a GeoTek Multi-Sensor Core Logger aboard the JAMSTEC drilling vessel Chikyu.
  • The instrument can be raised and lowered and the light source adjusted to accommodate samples of varying thicknesses.

Field setup


The imaging system can be mounted on a Headwall-supplied tripod with a fine motion-control rotational stage to acquire panoramic images of outcrops from a few meters distance to infinity. While the precise spatial resolution varies with distance from the outcrop, the effective instantaneous field-of-view (IFOV) on target from a standoff distance of 20 m is 0.6 cm (VNIR) and 1.7 cm (SWIR).

  • Our custom lightweight battery system can power the instrument for ~15 hours of continuous runtime with no need for a generator.
  • The imaging spectrometer fits in an 80 L backpack, and other components are easily carried by 1-2 others.
  • Calibration targets of varying reflectance levels assist in atmospheric removal and calibration of the data.