The US Naval Research Laboratory has demonstrated a passive, broadband (8.4 to 11.2 µm), LWIR spectrometer with a resolving power of ~500 that has no moving parts, is immune to scene changes and has high throughput. It uses a compression assembly spatial heterodyne spectroscopy (SHS) interferometer (C-SHS) which employs precision spacers that result in a robust, self-aligning, economical assembly, and enables easy replacement of optical components.
The basic principle of spatial heterodyne spectroscopy is similar to a Fourier-transform spectrometer (FTS) in that it also features a beamsplitter which divides the incoming signal into two interferometer arms. However, in SHS, the latter terminate at fixed, tilted gratings that impose a wavelength-dependent tilt onto the diffracted wavefronts. After recombination at the beamsplitter and imaging onto a detector array, a complete interferogram can be recorded without using any moving parts.
- Rugged: No moving parts coupled with a self aligning, nestled design
- High throughput: Performance comparable to field widened FTS but much easier to design and implement field widening concepts
- Excellent on moving platforms and rapidly changing scenes: SHS is insensitive to spectral errors caused by changing scenes. It is ideal in applications where jitter is a concern such as on airplanes or ground vehicles and for imaging fast events such as combustion processes or explosions.
- Reduced manufacturing cost: Broadened optical tolerances coupled with the simple flexible design allows C-SHS to enjoy reduced costs and assembly time compared to traditional monolithic SHS
- SHSs have been successfully deployed for satellite remote sensing of the Earth’s atmosphere, planetary astronomy, and laboratory spectroscopy. C-SHS in LWIR has been demonstrated in the laboratory.
- Available for license and commercialization
- Peer-reviewed journal articles
- Potential for R&D collaboration with inventor