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Range-gated active imaging in SWIR

Eye-safe Active Imaging

NIT have developed solutions in SWIR gated imaging. The products are offered with QVGA (320x256) or VGA (640x512) resolution, with USB3.0 or Camlink interface.

gated SWIR cameraThanks to its patented logarithmic pixel technology architecture, the WiDy SWIR cameras allow ultra-low exposure time (200 ns) fully synchronized with short pulse eye-safe laser (e.g. 1,55 µm) with utmost shutter efficiency outperforming any other InGaAs solutions on the market.

The latest Smart embedded Camlink camera Widy SWIR 640M-SPE (all image processing carried on FPGA) features a rise time of 20 ns from 10 to 90%, a jitter <10 ns and a delay capability programmable in 30 ns steps. With an adequate optic and laser it allows users to reconstruct a scene kilometers away by tomography technique in slices of 30 m (3 m precision) day or night, through various obscurant such as smoke, pollution or fog.

Technolgy

Short Wave InfraRed (SWIR) cameras based on InGaAs imagers work in a reflective imaging mode like visible and at the same time in detection mode of infrared radiation emitted by hot objects (>250°C). With a spectral response from 900-1700 nm, they are the solution of choice for decamouflage, seeing laser spot and through fog, smoke and foliage.

For extending vision capability of SWIR imagers especially at night, additional active lighting by LED or laser is often used. To remain covert, very short eye-safe laser pulses (1.5 µm) are used allowing thus gated imaging.

Several issues can be encountered in this domain which can impair a clear vision of the scene.

What do we offer?

With linear response SWIR sensor, the shutter efficiency is limited; NIT SWIR logarithmic response global shutter design offer the most efficient solution (close to 100%) on market.

In gated imaging, the exposure time defines the depth resolution. We offer very short exposure time down to 200 ns with low jitter (>10 ns) and minimal trigger delay. This translates into a depth resolution of 30±3 m.

Full well capacity of standard SWIR are limited and therefore prone to saturation on high level illumination. This is not an issue at all with our cameras. The NIT sensors offer a unique patented solution to these issues. The native logarithmic response allows for an instantaneous almost infinite dynamic range of over 140 dB with a single exposure. There is no need to sense the scene to adapt integration time like traditional HDR solutions that need time to analyze the image to adapt itself. Working in a solar-cell mode, there is no lag and no temperature dependence. The sensor behaves like the human eye and its performance can be immediately appreciated by the user.

To summarize, SWIR solutions from NIT offer unique features essential for high-quality active gated imaging.

Special Features

  • native logarithmic response
  • no saturation
  • instantaneous accommodation to light changes
  • simple controls with single exposure time
  • maximal shutter efficiency
  • high and constant injection efficiency

Further details

For detailed technical presentations please follow these links:

White paper active imaging
WDR log InGaAs sensor for eye-safe