Why is ultraviolet light sometimes used for illuminating objects that should be imaged.
An object, that we can’t detect easily with visible light can be imaged being illuminated by ultraviolet light. Ultraviolet light is electromagnetic radiation with shorter wavelength and higher frequency. For this , ultraviolet light is invisible to human eyes. Ultraviolet light has more penetrating power than visible light. So, within an object ultraviolet light reaches easily and the radiation causes the object fluoresce. Now a days, for many purposes ultraviolet light is being used for detection. Detecting problem under skin, detecting evidence like-human secretions and stains from a crime spot, detecting originality of money, checking security cards are the common uses of ultraviolet light. The marks given for identification are not visible with eyes but can be seen under UV .
Sun emits uv and there are other sources of UV by which an object can be illuminated. An object under UV, emits radiation can be imaged by a camera which only allows UV to reach it’s lens.
To have a precise image of an object, that need to be placed under a UV source. Then with a camera that absorbs all lights except UV, an image can be taken.
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