Machine vision lighting has different color and wavelength requirements compared to human-centric lighting. Most electronic sensors such as CCDs or Charge Coupled Devices tend to be more sensitive to deep red and near-infrared wavelengths between 600-900nm. There are also InGaAs-based sensors used specifically to monitor the short-wave infrared (SWIR) spectral region between 900-1700nm. In general, a direct correlation exists between the lighting wavelength and its penetration ability. For most materials, longer wavelength light such as red or infrared will penetrate deeper and reveal more details compared to short wavelength light. Depth measurement technologies such as LIDAR often use infrared lasers and sensors to reveal details not available to conventional cameras or the human vision system.
An ideal machine vision lighting source would have high color rendition in the visible parts of the spectrum while simultaneously deliver light rich in red and near-infrared wavelength for detailed imaging and deeper material penetration. We have developed various phosphor-converted LED (pcLED) solutions that can be used for such purpose. Such pcLEDs can be used to manufacture compact and high brightness lighting sources that can be customized for specific machine vision applications. This includes hyperspectral and multispectral technologies for capturing images and information from a broad segment of the electromagnetic spectrum covering both the visible and infrared.
The data below shows an emission spectrum from Vis-NIR COB pcLED device. The device can deliver high color rendition (CRI>90) and warm light with correlated color temperature (CCT) around 3000K. In addition, the pcLED emits various near-infrared spectral lines covering the 850-1150nm parts of the electromagnetic spectrum. Both the visible and IR parts of the spectrum can be customized with SWIR emission up to 1500-1700nm using various IR phosphor materials. Near-infrared enhanced LED lighting is also available as a plug-and-play fixture.
A COB LED capable of delivering both high CRI (>90) visible lighting in addition to near-infrared. The source can function as a warm white LED with CCT around 3000K and/or a near-IR emitter. The visible light emission can be suppressed using various optical filtering or down-conversion techniques.