Light emitting diodes for illumination in photoelasticity

Journal Article · Tue Jul 15 00:00:00 EDT 1997 · Experimental Techniques

DOI:https://doi.org/10.1111/J.1747-1567.1997.TB00537.X· OSTI ID:22771577

Ng, T. W. ^[1]; Asundi, A. ^[2]

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1. National University of Singapore, Department of Mechanical and Production Engineering (Singapore)
2. University of Hong Kong, Department of Mechanical Engineering (Hong Kong)

ConclusionIn this paper, the performances of conventional incandescent and discharge lamps in photoelasticity are compared with LED devices. LED devices are found to have superior luminous efficacy, lamp life and flash response. Although the spectral bandwith of LEDs is broader than that of sodium discharge lamps, they are within the 100 nm limit necessary to ensure measurement accuracy. LED devices are also easily available in a range of wavelengths that enhance their application in photoelasticity when birefringent materials with selective spectral absorption characteristics have to be illuminated. With the availability of LEDs that radiate at different wavelengths, selection can be easily done by simple electrical switching. Due to their miniature construction, LED devices can also be designed as flat panel illuminators by connecting them up on printed circuit boards. Due to their versatility and improved characteristics, it is easy to conclude that LED devices are ideal for use as illuminators in photoelasticity. For a lens polariscope, a single LED provides adequate illumination and eliminates the problem with a multiple source image at the recording plane. It has been shown that a single LED provides adequate illumination even at exposure times of 1 µs. This has been used to develop a low cost Cranz-Schardin system.

• OSTI ID: 22771577
• Journal Information: Experimental Techniques, Vol. 21, Issue 4; Other Information: Copyright (c) 1997 Society for Experimental Mechanics, Inc.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0732-8818
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ABSORPTION
ACCURACY
ILLUMINANCE
LENSES
LIGHT EMITTING DIODES
MATERIALS
PHOTOELASTICITY
PRINTED CIRCUITS
WAVELENGTHS