Downloaded from https://www.everyspec.com MIL-sTo-8ioc h. Radiant flux, also,radiant ““power($). Radiant fIux, also radiant power, is the average radiant e“nergy’ emitted, transferred or received as radiation per unit time per unit area. i. Radiation, infrared. Infrared radiation‘is radiation for which the: ~ wavelengths are greater than those for visible radiation and less than about O.1 millimeter. . .: j. Solar“beam incident”angle. The solar be~ incident angle is the angle measured at an arbitrary point in the test volume (see figure below)’between the incident rays striking that,point and a line parallel to the axis of the solar beam.
The angle be measured so that 95 percent “ormore of the solar energy incident at the aforementionedpoint is included. The maximum incident angle, usually fourid at “theextreme edge of the’test volume (or plane), is sometimes referred to as the solar beam divergence angle. J APPARENT SOURCE SOLAR BEAM AXIS INCIOENT ANGLE SUBTENSE ANGLE DIVERGENCE ANGLE —ARBITRARY POINT Figure 517.2-1. Geometrical Relationship of Solar Subtense and Incident Angle k. Solar subtense angle. The solar subtense angle is that angle subtended I by the maximum dimension of the apparent source at an arbitrary point on the I test specimen. (See figure above.) I NOTE:
The terms .decollimationangle” and field angle, are sometimes used for subtense angle. The term subtense angle is preferred. The angle shall be measured so that 90 percent or more of the simulated solar energy incident at any point in the test volume is r6ceiiredfrom the apparent source as herein defined. METHOD 517.2 517.2-12