S. Fine

Biological effects of laser radiation.

Abstract : A summary of studies carried on during the year on (1) Anterior chamber measurements on CO2 corneal irradiation; (2) corneal calcification on CO2 laser irradiation; (3) ocular injury from CO2 laser irradiation; (4) application of thermal models to retinal threshold injury; (5) toxic and explosive hazards associated with lasers; (6) pathology of internal viscera following laser irradiation; (7) a method for detecting and measuring frequency of surface vibrations using a helium neon laser; (8) exploration of potential carcinogenic effects of pulsed laser irradiation; (9) lasers in biology and medicine; and (10) rupture and tensile strength measurements of fresh and treated canine aortic tissue. (Author)

Laser irradiation of biological systems

Investigations with the laser are in progress that may more clearly illuminate living processes. Applications to problems in biology and medicine are under exploration

Biological effects of high peak power radiation

Abstract 1. Interactions at high peak powers (greater than 10 8 watts) and at high peak power densities (greater than 10 watts/sq. mm), but relatively low energy levels (3 joules) between laser radiation and biological systems have been observed. 2. Qualitative as well as quantitative differences due to variations in peak power and in power density at equivalent energy levels of laser radiation were considered in the studies of the biological effects. Further studies should assist in elucidating the importance of high peak power as a parameter in the interactions between laser radiation and biological materials. 3. The similarities of the biological effects of laser radiation at high peak power and low energy and those of laser radiation at low peak power and higher energy output were noted.

Some effects of laser radiation on the skin of the Syrian hamster

Abstract In preliminary studies Syrian hamsters were exposed to radiation emitted by a laser utilizing a neodymium-doped glass rod. Lasered beams at 30 joule and 50 joule were focussed onto the surface of the anterior abdominal wall and of the exteriorized cheek pouch. Lesions resembling thermal burns were induced. The animals showed no other ill effects. Current studies deal with the manner in which dyes may modify the effects of lasered radiation, and with the actions of lasered radiation of higher intensities.

Effects of pulsed laser irradiation of the forehead in mice

Abstract 1. Non-focused or focused laser irradiation of the frontal area of mice produced neurological damage, followed by death in 75% within 24 hours of irradiation. These effects are attributed to other than thermal effects. 2. Initial studies with laser radiation delivered at high peak power (greater than 100 megawatts) appears to cause greater damage than at lower power levels. Consequently, power, and power density as well as energy delivered, may be of considerable importance in regard to the interaction with biological material, and radiation. 3. Attention should not be limited to the superficial area of interaction in personnel accidentally exposed to laser radiation. Deep effects may be of greater severity than the superficial lesion.

Effects of laser irradiation on some serologic properties of human gamma globulin.

Abstract High and low intensities of laser irradiation of 1 percent saline solutions of human (HGG) and rabbit (RGG) gamma globulin produced different effects than that of a thermal nature per se upon the precipitin reactions with rheumatoid factor. Heat treatment of globulin solutions at 63°C. for 15 minutes caused aggregation and measurably more precipitation with rheumatoid factor than untreated globulins, whereas the laser irradiation reduced or destroyed the capacity for the globulins to precipitate rheumatoid factor. Precipitin reactions between rabbit anti-HGG and laser irradiated HGG demonstrated a shift of position of precipitin curve peaks, as well as reduction of total amount of precipitation. Ultracentrifugal analyses to date did not reveal additional components with laser irradiation of HGG, as were observed with heat treatment of globulins. Immunochemical agar gel diffusion and immunoelectrophoretic analyses revealed slight differences of laser irradiated from native globulins. It was concluded that the interactions of high intensity electromagnetic (laser) radiation with globulins differ from those of heat per se, as demonstrated by differences in the serologic activity, certain physico-chemical changes and other pertinent parameters of the respective reactions.

A Method for Detecting and Measuring Frequency of Surface Vibrations Using a Helium‐Neon Laser

CW helium-neon laser used to detect and measure vibration frequencies of uniform diffuse surfaces

HAZARDS OF LASER RADIATION: MECHANISMS, CONTROL, AND MANAGEMENT.

Abstract Analysis of biological studies indicate the factors responsible for hazards associated with laser systems: (1) the laser radiation and its interaction with the biological system, (2) the pumping source, (3) the high voltage and current required for operation of a laser system and, (4) the environment in which this system is used. Short-term and long-term hazards associated with the beam are dependent on the properties of the radiation and those of the biological system. Hazards associated with flashtubes must be considered, particularly since misfire or accidental firing can occur. Long-term effects on the eyes due to either a single insult or to cumulative subthreshold insults are not yet known but continue to present a potential hazard. Hazards to the skin must also not be neglected in continued testing.

Biological Effects and Hazards of Laser Radiation.

Excerpt The range of biological effects and the potential hazards of laser radiation are increasing as rapid technological advances provide increasing energy and power levels in the ultraviolet, vi...

Effects of Laser Radiation on Biological Systems.

Excerpt Studies on the effects of laser radiation in normal and tumor bearing animals and on isolated biological systems have been carried out. Animals included hamsters, mice, rats, and monkeys. T...