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Lasers in Medical Science

, Volume 16, Issue 1, pp 34–39 | Cite as

Visual Observation of Infrared Laser Speckle Patterns at Half Their Fundamental Wavelength

  • T. Theodossiou
  • E. Georgiou
  • V. Hovhannisyan
  • D. Yova
Regular Article

Abstract

. In the course of work aimed to examine second harmonic generation in biological macromolecules, it was discovered that 1064 nm pulsed nanosecond infrared laser radiation, after scattering on the optically rough sample surface, was perceived as double the fundamental frequency green speckle pattern by the unaided eye. The threshold of this arresting phenomenon was found to be around 60 mJ/cm2 on hyaluronic acid potassium salt in dark ambient conditions. This effect is of a second order non-linear nature. After experiments with nearsighted, farsighted and normal vision observers in combination with second harmonic generation experiments on various lamb eye tissues, the effect was mainly attributed to second harmonic generation in the cornea arising from phase interference of the incident infrared radiation. The current work could possibly have implications in the fields of speckle interferometry and biomedicine.

Keywords: Collagen; Corneal disorders; Laser speckle; Second harmonic generation 

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Copyright information

© Springer-Verlag London Limited 2001

Authors and Affiliations

  • T. Theodossiou
    • 1
  • E. Georgiou
    • 1
  • V. Hovhannisyan
    • 2
  • D. Yova
    • 1
  1. 1.Biomedical Optics & Applied Biophysics Laboratory, Department of Electrical and Computer Engineering, National Technical University of Athens, Athens, GreeceGR
  2. 2.Laboratory of Biomedical Optics, Applied R&D Division, Yerevan Physics Institute, Yerevan, ArmeniaAM

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