Figure 1: Spectrum of water-filtered infrared-A radiator (Hydrosun ® 500). Calculated for Hydrosun ® 500 with 4 mm water cuvette and standard yellow filter at approximately 385 mW/cm² (= 3.85 x 10³ W/m²) total irradiance intensity (in a distance of 25 cm), from Measurement of University of Applied Sciences Munich, dated June 30, 1999