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Laser‐speckle properties and their effect on target detection
Author(s) -
Gaska James P.,
Tai ChiFeng,
Geri George A.
Publication year - 2007
Publication title -
journal of the society for information display
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.578
H-Index - 52
eISSN - 1938-3657
pISSN - 1071-0922
DOI - 10.1889/1.2825086
Subject(s) - speckle pattern , optics , speckle noise , laser , luminance , spectral density , pixel , physics , contrast (vision) , noise (video) , computer science , artificial intelligence , telecommunications , image (mathematics)
— Laser projectors are currently being developed for use in high‐fidelity wide‐field‐of‐view displays. In order to assess the effects of laser speckle on target detection, contrast thresholds as a function of target spatial frequency on both a laser‐speckle background and a uniform‐luminance field have been measured. For all spatial‐frequency targets tested, speckle increased contrast thresholds relative to those obtained on the uniform field. In addition, a power‐spectral‐density metric for characterizing laser speckle and predicting its effect on target detection has been developed. To evaluate themetric, contrast‐energy thresholds on both a laser‐speckle background and backgrounds consisting of randomly modulated pixel luminance ( i.e. , pixel noise) have been measured. The results of previous studies, concerned with the detection of targets in wideband noise, suggest that these thresholds should be the same when the power spectral densities of the backgrounds are equated. It was found, however, that, for the same background power spectral density, energy thresholds on pixel noise were slightly higher than those obtained with laser‐speckle noise. This small difference could be accounted for, however, by the well‐documented individual differences in the optical parameters of the eye, particularly pupil size.