The objective of this presentation is to give a layman's definition for the phenomenon and a brief history of successful uses of daylight fluorescent colors in safety products and applications. Fluoresence is defined as the phenomenon in which light energy of a relatively short wavelength is converted into visible light energy of a longer wavelength. In comparing fluorescent and conventional red-orange color examples side by side under simulated daylight, the two surfaces appear quite similar. Both are obviously reflecting red-orange light to our eyes and the primary difference is that the fluorescent example is brighter. However, when the samples are illuminated with yellow-green light, something very unusual occurs. The conventional color appears to darken, while the fluorescent surface continues to emit a distinctive red-orange effect. This is due to its ability to convert yellow-green to red-orange, rather than absorbing the transmitted light as does the regular red-orange. The effect is even more dramatic with short wavelength blue-violent light. Conventional red-orange goes almost completely black, while the fluorescent again continues to emit bright red-orange color. Thus, fluorescent colors are brighter than ordinary colors because they are capable of converting light energy that is normally absorbed and wasted to visible light, which in turn reinforces the color in intensity. Hence, there is greater visibility in daylight conditions. (Author)

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    • Presented at the Symposium on Conspicuity on the Highway, St. Paul, Minnesota, 24-26 June 1980. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
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    Transportation Research Board

    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Authors:
    • Smith, H J
  • Publication Date: 1981-5

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  • Accession Number: 00335157
  • Record Type: Publication
  • Report/Paper Numbers: HS-032 446
  • Files: HSL, TRIS, TRB
  • Created Date: Oct 28 1981 12:00AM