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Evaluation of protection measures against laser dazzling for imaging sensors

: Ritt, Gunnar; Eberle, Bernd


Optical engineering 56 (2017), No.3, Art. 033108, 16 pp.
ISSN: 0091-3286
ISSN: 0036-1860
ISSN: 1560-2303
Journal Article
Fraunhofer IOSB ()
laser dazzling; pattern recognition; sensor protection; structural similarity index; triangle orientation discrimination

We present our work regarding the evaluation of protection measures against laser dazzling for imaging devices. Different approaches for the evaluation of dazzled sensor images are investigated to estimate the loss of information due to the dazzle spot: (1) counting the number of overexposed pixels, (2) based on triangle orientation discrimination, and (3) using the structural similarity index. The evaluation approaches are applied on experimental data obtained with two different sensors hardened against laser dazzling. The hardening concept of the first sensor is based on the combination of a spatial light modulator and wavelength multiplexing. This protection concept allows spatially and spectrally resolved suppression of laser radiation within the sensor's field-of-view. The hardening concept of the second sensor utilizes the principle of "complementary bands." The optical setup resembles a common three-chip camera, with the difference that dedicated filters with steep edges replace the regular spectral band filters. Although this concept does not really represent a "protection measure," it allows the sensor to provide information even in laser dazzling situations. The data for the performance evaluation were acquired both in a laboratory setup using test charts comprising triangles of different size and orientation as well as in field trials.