PVC被覆材料之光學特性測定

A Technique for Measuring Light Characteristics of Covering Materials in Agricultural Structures

本文提供一客觀的實驗測定法以了解被覆材料的光學特性。實驗設計包括日射量透過率測定、光照度透過率測定和分光波長輻射能量透過率測定等三部分。並測定台製和日製軟質PVC布被覆材料22種，結果顯示：抵達地面的太陽輻射能量中，可見波長區佔約三分之一能量，其中短波長側含有能量比極低，紅色光側能量比高，而以黃橙色波長區（560nm以上）的單位波長能量強度最高。透明PVC布的全日光能量透過率為86〜91%，其中可見光波區含有33%，不可見光波區則有67%。而可見光波區能量的透過率為90.3〜93.7%。至於日製及台製產品以及材料厚度不同，在透過率差異上並無明顯差別，只有在可見光波區內的短波長側，日製村比台製材有較高的分光透過率。即使不同著色PVC布，除了黑色及黃色霧狀等少數深色且噴霧處理的材料以外，均仍有高達82%及86%以上的光量和能量透過率。其中，透過霧狀材料的光線中，仍有70%光量和87%能量為直達光強度，且可見光波長能量透過率亦仍高達85%。除黑色PVC布以外，只有黃色霧狀PVC布可減低將近一半的透過率，達到63%光量及65%能量的透過率。

An objective measure technique is presented to measure the light characteristics of covering materials. Experimental designs include transmittance tests for solar irradiance, illumination tests, and spectral transmittance tests. Of twenty-two pieces of different PVC film covering materials tested, all of those were made in Taiwan and Japan, being tested. The results show that one third radiation energy belongs to the visible wavelength range in global solar energy, the unit wavelength energy of the short wavelength is much smaller than the long wavelength, and a yellow-orange light wavelength (above 560nm) posses the largest unit wavelength energy within the visible wavelength range. For the clear PVC film, the solar irradiance transmittance is about 86~91% and is composed of 33% visible wavelength and 67% un-visible wavelength, while the total energy transmittance is about 90.3~93.7% in the visible wavelength range. Both the clear PVC films made in Taiwan and in Japan, with different thickness (0.13~0.40 mm) have no visible difference transmittance, except that the PVC made in Japan have a high spectral transmittance in short wavelength range than that made in Taiwan. When the colour and mist is added in PVC film, the high illumination (82%) and solar irradiance (86%) is observed except two types of the black and yellow-mist PVC film, and about 70% of the transmitted illumination and 87% of the transmitted energy belongs to direct light. In addition, high spectral transmittance (85%) in visible wavelength range is also observed in color and mist PVC film. Among all tested PVC films except black color film only yellow-mist PVC film can get near a half transmittance of the illumination (63%) and the solar irradiance (65%).