Posted in | Photodetectors

Application-Specific Near-Infrared Software Module

Devices use near-infrared (near-IR or NIR) light emissions to detect three-dimensional (3D) objects beyond the human visible spectrum, thus avoiding human visual distraction and visible light interference.

However, since NIR emissions are known to be “invisible,” test equipment needs to be utilized to guarantee sufficient intensity and distribution of NIR light for detecting objects.

The TT-NIRI module is part of the TrueTest™ Software family from Radiant Vision Systems. This application-specific software module offers the advantages of the TrueTest™ Software to efficiently carry out image-based measurements. But this comes with application-specific tests to assess the precision of 850 or 940 nm NIR LEDs, structured light patterns, and lasers that are utilized for:

  • Eye-tracking as well as iris detection
  • Gesture and facial recognition
  • Multimodal sensing for motion and gesture control
  • Automotive LiDAR for sensing autonomous vehicles
  • Other non-visible 3D sensing applications

Radiant Vision Systems offers a complete NIR test solution that integrates the TT-NIRI application-specific software module with its NIR Intensity Lens solution, to carry out fast and automated visual inspection of NIR emitters.

Application-Specific Near-Infrared Software Module

With the help of the Fourier optics of the NIR Intensity Lens solution, the TT-NIRI assesses all angular emissions of a source in one image, and also all the dots in a structured light pattern generated by diffractive optical elements, or DOE.

When compared to a goniometric or spot measurement device, a Radiant NIR test solution has the ability to capture and process data relatively faster and more reliably. Captured by the TT-NIRI software and the NIR Intensity Lens, the DOE dot source analytics provide complete radiometric data. This data cannot be achieved through alternative techniques like casting a dot pattern against a wall or other similar Lambertian surface.

Supported products — NIR Intensity Lens solution

System requirements:

  • NIR Intensity Lens solution
  • Windows® 10, 64-bit
  • 16-32 GB RAM
  • Additional system requirements vary by camera.

Comprehensive NIR Test Suite

Assessing the precision of NIR emissions depends on radiometric measurements to establish the intensity and scope of NIR-emitting sources, and also the angular position of accurate emission points (dots) against defined tolerances.

An all-inclusive NIR test suite provided by the TT-NIRI module enables users to define measurement parameters as well as pass/fail criteria for certain points of interest in a single image. Specific tests are included in the software module for NIR light source measurement, including:

  • Max. power
  • POI total power
  • Total flux (mW or W)
  • Dot source analysis
  • Pixel solid angle
  • Inclination solid angle
  • Image export
  • Points of interest
  • Flood source analysis

Angular Distribution of a Source

Cross-section radar plot in TT-NIRI software showing radiant intensity as a function of angle for a NIR LED light distribution.

Cross-section radar plot in TT-NIRI software showing radiant intensity as a function of angle for a NIR LED light distribution.

Diffuse “Flood” Source Analysis

Certain NIR applications depend on a powerful flash of NIR light (at times known as “flood” distribution) for proximity sensing, utilizing a time-of-flight (ToF) measurement. In facial recognition, for instance, flood emitters can be used for detecting the presence of a face and thus establish focus distance, even in darkness.

Within the TT-NIRI software, the “Flood Source Analysis” test quantifies the flood function of these light sources to make sure that they conform to the planned performance parameters, and to detect any irregularities like intensity fall-off or hot spots.

Analyze flood distributions from diffuse NIR light sources

Analyze flood distributions from diffuse NIR light sources to evaluate uniformity across angular emissions (in terms of intensity at each degree), center values, angular fall-off, hot-spots, including:

  • Full width half maximum (or full width 90% maximum, etc.)
  • Average radiant intensity across the cross-section
  • Maximum radiant intensity across the cross-section
  • Slope widths (how long it takes the sample to “fall off” in degrees)
  • Edge slopes (mW/sr) per degree (metric for how quickly or slowly the sample “falls off” on the edges)
  • Center of the sample (degrees)

Structured Light Dot Pattern Analysis

The TT-NIRI module contains a “Dot Source Analysis” test to output flux statistics, maximum intensity, and uniformity for every dot in a structured light pattern generated by a NIR laser via a DOE. This test is capable of analyzing regions of dots or individual dots to make sure that the patterns are projected in the exact angle (inclination, azimuth) and with the exact intensity (W/sr).

Close-up on the analysis of dot source emissions used for 3D sensing like facial or gesture recognition. Each dot in the pattern can be evaluated for accurate position and intensity, with data output

Close-up on the analysis of dot source emissions used for 3D sensing like facial or gesture recognition. Each dot in the pattern can be evaluated for accurate position and intensity, with data output including:

  • Location in pixels (x,y)
  • Location in inclination/azimuth (degrees)
  • Intensity (W/sr)
  • Peak average intensity (mW/sr)
  • Peak solid angle (sr)
  • Pixels at maximum peak
  • Spot power uniformity (%)
  • Maximum peak radius (°)
  • Total flux (mW or W)
  • DOE flux (mW)
  • Image export

As with all the TrueTest platform modules, tests from the TT-NIRI test library can be introduced to a sequence, and pass/fail settings and test parameters are input for every test. It is possible to run the whole sequence end-to-end automatically and store it so that numerous sequences can be generated and recalled as required. In addition, individual test outcomes are shown and can be captured in a report.

Complete Measurement Solution

The TT-NIRI module offers application-specific testing for comprehensive NIR emission measurement. It is utilized with a ProMetric Y Imaging Radiometer coupled and calibrated with the Radiant NIR Intensity Lens. This setup offers a turnkey radiometric imaging solution that fulfills the form factor as well as the cost needs of users’ applications.

The TT-NIRI module

The TT-NIRI module — supported by Radiant Vision Systems’ universal support staff and distributor network — is field-proven and has been used for testing 3D sensing technology for the new, high-end devices in automotive and electronics applications.

Key Features and Highlights of the TT-NIRI Module

  • Emitters can be characterized in the laboratory for research and development; data can be used as a benchmark at the time of production for real-time quality control
  • Predefined tests can be rapidly applied for measuring NIR emissions
  • Hardware integration and software test sequencing enable automated production-level testing
  • Complete angular measurements can be captured concurrently for optimal efficiency of the production line
  • Data analysis functions, such as cross-sections, bitmaps, radar plots, and isometric plots, can be used
  • Data files can be easily changed within the Radiant range of software

Typical Applications

The TT-NIRI module helps in assessing NIR emissions to achieve high-resolution measurements of angular distributions of NIR light, and also structured light dot patterns created by DOE.

  • Assessment of 850 or 940 nm light sources can be performed for precise radiant intensity output at angles of ±70°.
  • Can be used with the Radiant NIR Intensity Lens solution.
  • Angular measurement can be made for devices employed for 3D sensing applications such as gesture recognition, facial recognition, automotive LiDAR, multimodal human-machine interface (HMI), and eye-tracking.

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