![]() The total energy of all the light given off is termed the “luminous flux.” Effectively, it sits at the center of a sphere of radiated light (which is why light units reference the steradian). Fluorescent lights appear white only as a result of fluorescence from a coating on the glass or tube and LEDs emit light only at one specific wavelength.Ī light source, like the filament of an incandescent bulb, emits light in all directions. The actual distribution of wavelengths within that light depends on the temperature of the source. Light sources based on heat (“incandescent” sources) radiate electromagnetic energy across all wavelengths, which is why they appear white. Longer wavelengths are termed infrared (which is sensed as heat) and shorter waves are ultraviolet and then x-rays. Light with a wavelength around 420 nm is perceived as blue, 525 nm is green and 635 nm is red. Individual wavelengths correspond to distinct colors. The difference is that humans possess receptors able to sense energy with wavelengths between 400 and 700 nm and turn it into images. Like microwaves and x-rays those waves have a wavelength and a frequency. Light is a form of electromagnetic energy that travels through space as a wave. To aid in understanding light intensity measurement this White Paper from OMEGA Engineering addresses: In addition, good lighting determines how well people can observe a show and take quality photographs. Industrial accidents are more common when light levels are low. Working under poor lighting causes fatigue and mistakes. That’s why precision work like surgery, measurement or assembly is best done under bright light. The eye is sensitive to a very wide range of light intensity but at low levels loses the ability to discern detail. Light reflects off surfaces into the eyes, passing through the cornea and pupil to form an image on the retina. How Bright is it? Shining a light on intensity measurement ![]()
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