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(a) Transmission of light at 0.1 mm* dependent upon skin type. (b) Transmission of light beyond 1.93 mm* dependent upon skin type. FST I–II, red; FST III–IV, green; FST V–VI, blue. *0.1 and 1.83 mm correspond to the average epidermal and dermal thickness respectively giving a total depth of 1.93 mm.43
