Optical power control filters: from laser dazzling to damage protection

Donval, Ariela; Golding, Karin; Nevo, Doron; Fisher, Tali; Lipman, Ofir; Oron, M.

doi:10.1117/12.905336

Cited by 3 publications

(1 citation statement)

References 5 publications

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“…Therefore, other protection techniques are necessary. Protection techniques include micro-mirrors blocking certain regions of the scene [11], optically limiting filters [12] and frequency agile filters [13]. Wavelength independent laser protection devices are however only in the research phase and due to their complexity they are not expected to be spread in large numbers.…”

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confidence: 99%

Laser dazzling impacts on car driver performance

et al. 2013

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A growing problem for the Police and Security Forces has been to prevent potentially hostile individuals to pass a checkpoint, without using lethatl violence. Therefore the question has been if there is a laser or any other strong light source that could be used as a warning and dazzling device, without lethal or long term effects. To investigate the possibilities a field trial has been performed at a motor-racing track.A green CW laser with an irradiance on the eye of maximum 0.5 MPE, as defined by ICNIRP [1] and the ANZI standard [2], was used as a dazzle source.Ten drivers have been driving with dipped headlights through a course of three lines with orange cones. In every line there has been only one gate wide enough to pass without hitting the cones. The time through the course, the choice of gates and the number of cones hit have been measured. For every second trial drive through the track, the driver was exposed to the laser dazzler. The background illuminances ranged from a thousand lux in daylight to about ten millilux in darkness. The protective effect of the sun-visor of the car was investigated. The drives visual system was carefully examined before and after experimental driving and a few weeks after the experimental driving to verify that no pathological effects, that could potentially be induced by the laser exposure, pre-existed or occurred after the laser exposure. An analysis of variance for a within subjects design has been used for evaluation.It was found that green laser light can have an obvious warning effect in daylight. Dazzling does reduce the drivers ability to make judgments and manouver the car in twilight and darkness. A sun-visor can reduce the glare and give the driver an improved control, but that perception can be unjustified. No damage to the visual system was observed.

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confidence: 99%

Laser dazzling impacts on car driver performance

et al. 2013

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How to assess good candidate molecules for self-activated optical power limiting

et al. 2018

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Abstract. Reverse saturable absorbers have shown great potential to attenuate laser radiation. Good candidate molecules and various particles have successfully been incorporated into different glass matrices, enabling the creation of self-activated filters against damaging laser radiation. Although the performance of such filters has been impressive, work is still ongoing to improve the performance in a wider range of wavelengths and pulse widths. The purpose of this tutorial is, from an optical engineering perspective, to give an understanding of the strengths and weaknesses of this class of smart materials, how relevant photophysical parameters are measured and influence system performance and comment on the pitfalls in experimental evaluation of materials. A numerical population model in combination with simple physical formulas is used to demonstrate system behavior from a performance standpoint. Geometrical reasoning shows the advantage of reverse saturable absorption over nonlinear scattering due to a fraction of scattered light being recollected by imaging system optics. The numerical population model illustrates the importance of the optical power limiting performance during the leading edge of a nanosecond pulse, which is most strongly influenced by changes in the two-photon absorption cross section and the triplet linear absorption cross section for a modeled Pt-acetylide. This tutorial not only targets optical engineers evaluating reverse saturable absorbing materials but also aims to assist researchers with a chemistry background working on optical power limiting materials. We also present photophysical data for a series of coumarins that can be useful for the determination of quantum yields and two-photon cross sections and show examples of characterization of molecules with excited triplet states.

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