Figure 1

Spectrophotometric measures of illumination are shown comparing daylight with the white and red treatment lights. Sunlight was measured with the photometer pointed towards the horizon (and shaded from direct sun) near noon on a clear sunny day (32.85 North latitude, 2/2/05). White light was measured at 18" with the photometer oriented towards the center of the box. The red light was measured with the photometer adjacent to the diffuser, because at 18" the illumination was too dim to be plotted on the same scale. The irradiance scale was arbitrary (uncalibrated) but identical for the three measures.