Photometry: Understanding Light and Human Vision

This lecture covers the principles of photometry, focusing on the relationship between light waves, human vision, and optical detectors. It begins with an introduction to the sensitivity of the human eye, highlighting that maximum sensitivity occurs at 550 nanometers, where one watt corresponds to 683 lumens. The instructor explains key concepts such as luminance, luminous intensity, and luminous flux, defining these terms in relation to light sources and detectors. The discussion includes examples of various light sources, such as the sun, incandescent lamps, and fluorescent lamps, illustrating their luminance and illuminance values. The lecture also delves into the efficiency of light sources, comparing the performance of incandescent lamps and LEDs, and explaining the conversion factors involved. The importance of color balance in light quality and efficiency is emphasized, particularly in the context of LED technology. Overall, the lecture provides a comprehensive overview of how light is measured and perceived, linking physical properties to human visual experience.