Miniature Visible/Near Infrared Imaging Spectrometer

Technology      

The invention is a miniature visible/near infrared imaging spectrometer which is small enough to be used in a UAV. This imaging spectrometer provides a spatial map of the spectra from different pixels of the ground image, dispersing the visible and near infrared spectra and covering the wavelength range 400 nm to 2500nm. The design includes a flat low-cost grating, which has minimal straylight, and a cemented doublet is used as the main optical element. The total device volume is a factor of 10 smaller than imaging spectrometer designs with comparable capabilities. The spatial keystone and spectral smile is controlled to less than 0.1 pixels, eliminating the need for data resampling. The simplicity of the fabrication and alignment scheme ultimately leads to a low-cost design suitable for commercial production.  

Problem Addressed

Imaging spectrometers have excellent viability in both process control applications and commercial remote sensing. However, due to the large size, they are not easily integrated on small vehicles such as UAVs. Existing reflective imaging spectrometers must be flown in aircraft instrument bays or in large wing pods. Some designs also use convex gratings which are in limited supply and often produce straylight. Finally, the all-reflective designs often need to be diamond turned, post polished and shimmed into tight alignment tolerances with respect to each other.  

Advantages

• Small size with excellent optical performance
• Simple design easy to fabricate and align
• No data resampling
• No convex gratings  

Publications

"Design of a Hyperspectral Imaging Spectrometer for Visible and Near Infrared Region Applications." In 2014 22nd Signal Processing and Communications Applications Conference, 2014.

"Spectral Imaging for Remote Sensing." Lincoln Laboratory Journal 14, no. 1 (2003).