Robert Wood: UV Light
Wood's patents and theoretical work inform modern understanding of the physics of ultraviolet light, and made possible myriad uses of UV fluorescence
Woods Lamp
A traditional Wood’s lamp contains Wood’s glass, which is a mixture of barium-sodium-silicate glass and 9% nickel oxide. This glass coats the inside of tubes through which the UV light is transmitted. However, Wood’s glass is unique in that it blocks much of the visible light passing through the filter. Wood’s lamp produces a peak wavelength of 365nm. The longer the peak UV wavelength, the more visible light will be produced, which will result in less fluorescence.
Woods Lamp In Dermatology
First Used In Dermatology In 1925
Pseudomonas Green Nail On Woods Lamp
Bodily fluids like saliva, semen, and vaginal fluid do not require a chemical agent to make them emit light. Instead, they fluoresce when exposed to the right (short) wavelength of light.
In 1919, physicist Robert Wood found that UV-A light, what he called “black light,” could be useful in detecting certain bodily fluids. The technique caught, and since then, the light has been known as Wood’s light or Wood’s lamp.
Semen fluoresces blue between 300-450 nm, in the ultraviolet range. The invisible (to us) UV rays don’t interfere with the fluorescence, so forensic experts can see the stains.
When semen is exposed to wavelengths between 430-470 nm (within the visible spectrum), it generates an orange fluorescence.
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