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Many commonly used IR LED or laser diode illuminators operate at or very close to 940nm. Bi940 filters feature a much narrower band design vs. BN940, which can be beneficial when used in situations where ambient light conditions might otherwise create poor contrast. These are frequently night vision, security, traffic control, LPR and industrial inspection applications.
NIR image sensors used in conjunction with 940nm illumination are also being used to support iris recognition in biometrics. When used as a secondary scanner (simultaneously with a primary, mobile scanning unit), the invisible 940nm band can similarly help improve finger-vein identification protocols. This technology identifies specific individuals using a distinct blood vessel pattern inside one’s hand. Use of a narrow band Bi940 filter can provide insurance in the event of unanticipated changes in ambient/background light. One application that is under development is to verify users in payment transactions instead of relying on a credit card.