Abstract
This work describes a study of perception of light signals used in aeronautics. Devices known as “obstruction light” (L-810 type, according to the Organization of International Civil Aviation OACI and the Federal Aviation Administration FAA) with LED technology were fed with square pulses of voltage, attaining flashes with imperceptible rise times. The lights were presented to observers, simulating the habitual vision conditions for these devices. With this diagram, perceptive comparisons for different flash frequencies were carried out, exploring especially the transition zone between flickering and steady vision of light. The test showed that an important number of people experienced a perceptive increase in such transition zone. The phenomenon, which can be related with to Broca-Sulzer effect, could be used in order to improve the signal visibility.
Highlights
When the frequency of a periodic luminous stimulus is lower than certain value, the visual system perceives the successive “offs”, producing the sensation of flickering light
That is, frequencies higher than frequency of fusion (FCF), the sensation produced by pulsing lights can be estimated by means of the mathematical relation known as Talbot’s law (Moon, 1936; Talbot, 1834), which assigns a temporal integrating function to the visual system
The group of observers that participated in the tests did not distinguish variations of ±15% in the successive presentations of the beacon with continuous light
Summary
When the frequency of a periodic luminous stimulus is lower than certain value, the visual system perceives the successive “offs”, producing the sensation of flickering light. The limit or transition frequency is known as critical frequency of fusion (FCF) This frequency, the luminance variation stops being seen and the result is the sensation of “steady light”. The luminance variation stops being seen and the result is the sensation of “steady light” In this last condition, that is, frequencies higher than FCF, the sensation produced by pulsing lights can be estimated by means of the mathematical relation known as Talbot’s law (Moon, 1936; Talbot, 1834), which assigns a temporal integrating function to the visual system. The critical frequency is around 30~50 Hz and depends on the stimulus intensity and the observer’s age, among other factors
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