UV (HL) rays & optical brightener solution

A small 20W halogen lamp (HL) produces some ultraviolet rays, mostly long wave UV (UVA) type but also little medium wave UV (on borderline with LW UV), although powerful halogen lamps give off much more MW (UVB) UV rays. This filtered lamp will produce fluoresence with optical brightener solution. The halogen lamp is inside a box and switched on for only short time.

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