LASERS AND MICROWAVES Part II LASERS
William T. Ham, Jr., A. M. Clarke
Early laser safety research laid groundwork for understanding how different electromagnetic frequencies affect biological systems.
Plain English Summary
This technical report by W.T. Ham Jr. examined the biological effects of laser radiation, focusing on optical electromagnetic sources and their potential health impacts. The research was part of a broader investigation into both laser and microwave radiation effects on biological systems. This type of foundational research helps establish safety standards for laser devices used in medical, industrial, and consumer applications.
Why This Matters
Ham's laser research represents crucial early work in understanding how optical radiation affects biological tissue. While we often focus on radiofrequency EMF from phones and WiFi, laser radiation operates at much higher frequencies in the visible and infrared spectrum, creating different biological interactions. The science demonstrates that all forms of electromagnetic radiation, from radio waves to lasers, can produce biological effects depending on intensity, duration, and tissue type. What makes this research particularly relevant today is our increasing exposure to laser sources in everyday devices like laser pointers, barcode scanners, and optical communication systems. The reality is that while laser safety standards exist, they're primarily based on acute thermal effects rather than potential long-term biological impacts that this type of research began to explore.
Exposure Information
Specific exposure levels were not quantified in this study.
Study Details
To examine the biological aspects of lasers and their potential effects on living tissue, particularly the eye, and to discuss the safety considerations and applications of laser radiation in medical and research contexts.
The primary hazard from laser radiation is exposure of the eye; radiation levels, if kept below those damaging to the eye, will not harm other tissues and organs of the body. Eye damage can range from mild retinal burns with little or no loss of visual acuity to severe lesions with loss of central vision, and up to gross overexposure with total loss of the eye. Long term exposure of the retina to wavelengths in the visible spectrum at levels not far below the burn threshold may cause irreversible effects and should be avoided. Long term exposure of the eye to the near infrared wavelengths can result in opacification of the lens and should be avoided. Overexposure of the cornea to ultraviolet wavelengths produces a painful inflammation of the corneal epithelium. Overexposure to a Q-switched laser is especially dangerous and can result in loss of the eye. Retinal lesions from overexposure to laser beams are usually small because of the spatial coherency of most lasers. However, gross overexposure can result in massive lesions. Optical instrumentation such as telescopes and binoculars increase the intensity of radiation on the retina by the square of the magnification. For exposure times long enough to attain temperature equilibrium, image size on the retina is an important factor. For a given irradiance on the retina in watts/cm2, both the time to reach equilibrium and the maximum temperature attained are strong functions of image size, being much less for small spot sizes than for large ones. Enough data are available currently to establish tentative safety standards. While the military departments, several Government agencies, a few States, and many industrial corporations have established their own safety standards, there is not always agreement as to what constitutes safe exposure levels. There is a need for the establishment of national standards to resolve some of these discrepancies. At the present time, lasers do not constitute an environmental health hazard to the general public in the sense that water and air pollution, noise, etc. do, yet there is no assurance that this may not be the case in the future.
Show BibTeX
@article{lasers_and_microwaves_part_ii_lasers_g3602,
author = {William T. Ham and Jr. and A. M. Clarke},
title = {LASERS AND MICROWAVES Part II LASERS},
year = {n.d.},
}