HIGH SIGNAL-TO-NOISE, LOW STRAY LIGHT
The holographic diffraction grating is fundamental to every Headwall Hyperspec® instrument. Headwall is the only spectral imaging sensor manufacturer that also makes its own diffraction gratings. These gratings are available to OEMs for their own spectral measurement applications, which include color measurement and biotechnology.
These components are all-original, not replicates. This assures a peak efficiency tuned to the wavelength of interest. Because Headwall's gratings are master-quality and based on a holographic process, several important benefits assure outstanding imaging performance. The first is low stray light, which in turn results in high signal-to-noise. Where spectral signals might be weak, having high signal-to-noise is crucial. Low stray light means that more of the desired signal reaches the focal plane array.
Aberration correction is a function of the groove structure of each grating. Typical image aberrations called 'smile' and 'keystone' are eliminated, which means an edge-to-edge crispness across the entire field of view.
The objective of a spectral imaging sensor is to collect very high spatial and spectral resolution, and achieve 'square pixels' on the focal plane array. Headwall precisely engineers its diffraction gratings to meet this objective. Replicated and ruled gratings introduce higher amounts of stray light and more of these unwanted aberrations.
Headwall's diffractive optics using gratings and mirrors approach allows for the production of spectral instruments that are small, light, rugged, and elegantly simple. The same basic design is fundamental and proven whether the imaging instrument is UV-VIS (250-500nm) or SWIR (900-2500nm).
The optical design is concentric, meaning reflected light reaches the focal plane without using any moving parts or components that would otherwise distort the image. There are no exotic glasses or crystals to impact robustness and serviceability.
Headwall's diffraction gratings are used by OEM customers for use in their own spectral measuring instruments. In addition, these gratings are the foundation for Headwall's spectral modules (also for OEM use) and for spectral imaging sensors (for OEMs and end-users).
Headwall manufactures sensors covering ranges such as the visible-near-infrared (VNIR) from 400-1000nm as well as the shortwave-infrared (SWIR) from 900-2500nm.