Proposed Specimen Chamber

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In order to study the environmental durability of materials used in building and construction applications, it would be advantageous to uniformly irradiate specimens under a variety of conditions. This could be accomplished by equipping each port with a specimen chamber in which temperature, relative humidity, mechanical loading and other factors can be independently controlled. Because each chamber is independent of the others, a multiplicity of environmental conditions can be evaluated in a given experiment. While the UV irradiance would be identical between the ports, narrow band-pass filters or neutral density filters can be installed at the exit port to study the effect of a narrow wavelength region or to adjust the intensity, respectively. Other unique exposure environments can also be created, including freeze/thaw cycling and acid rain.

It will be necessary to situate the specimen chamber at some distance from the integrating sphere exit port to accommodate specimens which need to undergo mechanical loading, due to the physical space taken up by the loading frame and specimen grips. In order to convey the highly uniform radiation from the sphere exit port to the above-described specimen chambers without loss of uniformity and with minimal loss in intensity, non-imaging optical devices will be utilized. Such non-imaging optical devices are also known as compound parabolic concentrators, Winston cones, and cone concentrators, and are considered to be more efficient than conventional image-forming optics in concentrating and collecting light.

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