Views: 0 Author: Site Editor Publish Time: 2022-09-07 Origin: Site
SWIR and hyperspectral imaging
Materials such as plastic and glass are transparent to illumination in certain regions of the SWIR band. Other materials, such as water and lipids, show strong absorption at specific wavelengths in this region, which can make them easier to see inside the package. For example, 1450nm light can image the moisture content in disinfecting wipes. Light in the 1450~1550nm band can also penetrate plastic. For medical products that use opaque packaging (such as bottles) to maintain efficacy, SWIR can be an effective solution for detecting information about the substance inside the sealed product. Recent technological developments have greatly improved the intensity of SWIR light sources compared to light sources of a few years ago.
Another powerful imaging technique is hyperspectral imaging. Hyperspectral imaging combines imaging with spectroscopy using broadband light sources to generate images based on these unique "fingerprints" because pharmaceutical formulations absorb specific wavelengths of light. Hyperspectral imaging enables product quality assessment based on chemical composition, such as distinguishing between similar-looking pills and detecting contaminants and foreign objects. Using an appropriate illumination source that provides uniform illumination over the entire wavelength range in a similar manner to sunlight is absolutely critical to provide high-quality measurement results.
Conventional white LEDs are not suitable for these applications because they have a strong blue component with an intensity drop around 480nm and a weak red component. Natural light LEDs do have a spectral distribution similar to sunlight and offer a high color rendering index of Ra98. This ensures that the observed color of the illuminated object closely resembles that of nature, making natural light LEDs the light source of choice for applications requiring accurate color reproduction.
However, since hyperspectral imaging requires illumination wavelengths beyond 700 nm, CCS has developed a single LED illumination source that provides a nearly flat spectrum between 400 and 900 nm. This range can be further extended to 1000nm by adding two LEDs with outputs at 930nm and 970nm.
