| 摘要 |
A 150-250w halogen lamp (11) with reflector (12) produces temperatures of 300 deg. C. at the focussing plane (S) - too high for e.g. polymethyl methacrylate (Perspex, Plexiglass RTM), on cost and technical grounds the preferred light-guide (3) material. A quartz - opt., glass - intercept (2) placed between the focussing plane and the guide end-face (31), having a length (L) 2 to 3 times the former's diameter, transversely diffuses (23) and attenuates the infra-red radiation, giving guide entry temperatures of 70 deg. C. The guide comprises numerous fibres of e.g. 500 microns diameter, adhesive-bonded. For arc or iodide lamps producing higher temperatures (700 deg.C), a homogenising glass-fibre intercept is inserted in front of the quartz, and a finned heat dissipator fitted.
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