Night-Vision Camera Combines Thermal And Low-Light-Level Images

By Raf Vandersmissen, XenICs NV

Even on moonless but starlit nights, highly sensitive InGaAs cameras still produce good images for short-wavelength infrared. By thinning the image sensor chip and with illumination right through the substrate, the wavelength range of the detectors can be extended into the visible spectrum to then span 400 – 1700 nm. Together with uncooled microbolometer arrays for long-wavelength infrared, this allows the design of universal analysis tools which can take advantage of the fusion of optical and thermal images.

IR imaging is already used successfully in many technical/scientific fields. Its development, like that of other imaging technologies, is heading in the direction of stronger resolution, increased sensitivity and higher speed.

Added to this is the multispectral capture across multiple IR spectral ranges. These begin with short-wavelength infrared (SWIR) which, with its wavelength of 0.9 – 1.7 µm, follows on directly from the visible spectrum (VIS) and is therefore also called near infrared (NIR). This is followed by mid-wavelength infrared (MWIR), which ranges from 3 – 5 µm. And long-wavelength infrared (LWIR), from approx. 8 – 14 µm, is also gaining in importance for various kinds of analysis.

As well as the improved performance of IR image sensors, their manufacture with common industry processes on standard production lines ensures steady price-reduction, which is bound to open up further application areas, including strong-selling ones, to IR array-sensor technology.