Two dimensional Keitz method for the radiant power measurement of planar ultraviolet excilamps

• qianwen zhu, FUSHENG LI, Qiuyi Han, and Shanduan Zhang
• received 01/29/2024; accepted 04/26/2024; posted 04/26/2024; Doc. ID 520397
• Abstract: The planar XeBr* and XeCl* excilamps emitting the non-coherent narrow-band UVB light (280-315 nm), are now widely used to cure the psoriasis and vitiligo as well as to synthetic Vitamin D. The two-dimensional integral formula has been deducted in this study, which is a good method and has great practical significance to calculate the total radiant power and assess the energy efficiency of planar UV lamp. The measured radiant power of planar white LED lamps through a two-dimensional Keitz formula has been compared with that of gonio-photometer, verifying the applicability of the formula. The optimum measurement distance is dependent on the lamp length, as 1.5L≤D≤3.5L, for which the derivation from the two methods can be controlled within 10%. The planar XeBr* excilamps have been measured and compared to the coaxial excilamps, which show the similar patterns of change for the radiant characteristics. Since planar radiant power formula only needs to measure the normal illuminance at a certain distance from the symmetric center of the lamp, it is more convenient to use and low-cost method to promote the development of large-sized planar ultraviolet lamps.