The measurement of optimal power distance in LEDs

Abstract

Background: The use of light technology in dermatology has grown rapidly over the last decade, with many developments in its use for the treatment of a wide variety of skin conditions from non-melanoma skin cancers to facial resurfacing for photo-damaged skin. Light-emitting diodes (LEDs) have attracted much attention in medical fields. Objective: (1) To assess the optimal distance of 630 nm LEDs (OmniLux®, (Phototherapeutics Ltd, the UK)) and 830 nm LEDs (Healite® (Lutronic, Korea)) for maximum power as determined by a power meter and (2) to apply theory to practical use. Methods: Two separate hinged planar light emitting diode arrays were studied: 1) the Omnilux ReviveTM (Phototherapeutics Ltd, the UK), which delivers non-coherent red light at a wavelength of 633±3 nm and 2) the Lutronic Healite (Korea), which delivers non-coherent light at a wavelength of 830±5 nm. An X93 power meter (Gigahertz-Optik, Germany) was placed against a black background in order to reduce the amount of reflected light. We measured the LED powers over a range of 3-25 cm in 1 cm increments. Results: On the irradiation side of the LED, power increases according to the mass effect of the radiation angle. However, at a certain distance, the power decline effect predominated over the amassment effect. In this respect, the LED light was estimated to be emitted in a reverse V shape. The proper irradiation distance for use in medical fields can thus be determined. Conclusion: The proper irradiation distance of LED will be useful and the proper use of LED under the subjects' shape will be done in many medical fields.