Friday, September 17, 2021

Melexis Integrates 940nm Bandpass Filter on Top of its iToF Sensor

Melexis has developed a new version of its time-of-flight 3D camera MLX75026 with a fully integrated infrared bandpass (IRBP) filter. By integrating the IRBP, it is no longer required to include a separate IR filter in the lens or sensor assembly. This solution is said to be unique in the industry. It reduces design complexity and cost, while creating more design choice when sourcing a lens.

An IR filter is mandatory in every ToF application to reduce out-of-band infrared light in the operating environment, which could otherwise lower the dynamic range of the sensor,” explained Gualtiero Bagnuoli, Optical sensors marketing manager at Melexis. “A separate filter adds cost and complexity to a design, but by using the MLX75026 with IRBP filter, engineers can avoid both the cost and complexity, and explore the benefits of time-of-flight sensing more easily.

The integration of the correct IR bandpass filter is not trivial: the passband must be adapted to the illumination and the filter shall accept light from a wide range of incidence at minimal spectral shift (optically hard filter). This facilitates the usage of ToF-lenses with high apertures (low f-number). Melexis is the only ToF sensor manufacturer currently offering this option, which is now available as a variant of the MLX75026.

MLX75026 with IRBP filter has QVGA (320x240 pixels) resolution with a 1/4 inch optical format and supports 940 nm illumination. Samples of the MLX75026 with IRBP filter are available now.

2 comments:

  1. I agree with the advantages of integrating the bandpass filter. But it's not unique in the industry at all. TI's OPT8241 and OPT8320 have had integrated bandpass filters for ages.

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  2. Albert Theuwissen - Harvest ImagingSeptember 18, 2021 at 4:03 PM

    Is the IR filter integrated on top of the image sensor, or is it part of the cover glass ? The spec sheet says : "double sided AR OR 940 nm bandpass filter". So this suggests that the bandpass filter is part of the cover glass. Am I right ???

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