carefully evaluate the reflections from the SPS for the blue light actions spectrum of this class of injury. This will be done in the following sections. The final class of retinal light induced injury, called the color-blinding lesion, was so named because it produces selective degeneration of one class of color receptors (11). It is produced by repeated, intermittent exposure to spectral lights. Short wavelength, blue lights destroy only the blue-sensitive cones, when the intermittent regime is repeated daily for 6 to 8 days. Similarly, green and red lights damage the green-sensitive cones, but they recover in between one and four weeks. Although the light intensities which produce these effects can be reached by unconcentrated sunlight, it seems extremely unlikely that the required alternate bleaching and recovery repeated day after day would occur from viewing the SPS, so we can dismiss this class of damage as a hazard. Thus, it is clear that only the blue light produced photochemical lesion to the retina should be of concern as a possible hazard from viewing the elements of the Solar Power System from the earth. Therefore, in the following we will perform a quantitative assessment of the likelihood and conditions for such injuries for those elements of the system which produce sufficient irradiance on earth to be likely hazards. 3.1 Retinal Light Hazard Evaluation for Photochemical Injury from the Sun The American Congress of Governmental Industrial Hygienists (13) has recommended maximum permissible exposure values for viewing both point and extended light sources based on an analysis of the evidence for photochemical injury. They recommend that exposure to extended sources - those which subtend a solid angle at the eye greater than 1 X 10-4 steradian - should not exceed 100 Joules per square centimeter per steradian of blue light. Thus:
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