Recent advancements in sensor and optics manufacturing technologies for UV and IR wavelengths have made imaging systems for these wavelength ranges more accessible.
As of recent years, the demand for machine vision systems that capture information in the ultraviolet (UV) and infrared (IR) spectral ranges has increased as more integrators and end users venture into new application spaces. These imaging techniques take advantage of unique light-matter interactions outside of the visible spectrum. The span of applications and industry spaces for these imaging techniques includes package or label inspection for the food and beverage industry, hyperspectral imaging and multispectral imaging for environmental monitoring and agriculture, material sciences and semiconductor inspection, and so many more. Even though imaging out in these spectral ranges is recently less cost-prohibitive and more accessible, many of the design and manufacturing approaches for camera sensors and optical lenses are the same and the same technological advances that drive down costs associated with these more novel applications are improving visible imaging system technologies as well. However, there are several key differences in the technology for both UV and IR imaging.
Camera sensors are an array of pixels that consist of a semiconductor photodiode substrate, metal wiring, and a microlens array. Seen in Figure 1, there are two main sensor architectures, both with a different order to the orientation of the constituent layers. Backside illuminated (BSI) sensors as show in Figure 1 A) feature superior signal-to-noise ratios and more even illumination across the entire sensor than frontside illuminated (FSI) sensor, shown in Figure 1 B), as the incident light has less depth to penetrate for a BSI sensor than for an FSI sensor.