Mims Forrest M
Geronimo Creek Observatory, Seguin, TX, USA.
Photochem Photobiol. 2003 Jan;77(1):30-3. doi: 10.1562/0031-8655(2003)077<0030:aysoan>2.0.co;2.
Light-emitting diodes (LED), which are designed as quasi-monochromatic light sources, can also function as spectrally selective photodiodes. This provides a new kind of photosynthetically active radiation (PAR) sensor that is inexpensive and has much better stability over time than interference filters used in some PAR sensors. The action spectrum of photosynthesis in green plants has principle peaks in the blue and red regions. LED with response peaks in the UV-A (380 nm) and red (620 nm) regions have been used to measure PAR at or near solar noon in an ongoing study begun on 30 April 1996. The sum of the signals from the two LED is highly correlated with measurements by a calibrated filterless PAR sensor (Apogee QSO; Logan, Utah) from 13 September 1997 to 16 January 2002 (r2 = 0.97). The sum of the LED signals is also highly correlated with measurements by a calibrated filter PAR sensor (LI-COR LI-190SA; Lincoln, Nebraska) from 20 April 1998 to 16 January 2002 (r2 = 0.97). Thus, pairs of spectrally selective LED can function as PAR detectors in economical PAR radiometers. The separate 380 and 620 nm responses also permit an assessment of the differential impact of aerosol events on blue and red PAR and phototropic radiation.
发光二极管（LED）被设计为准单色光源，也可作为光谱选择性光电二极管发挥作用。这提供了一种新型的光合有效辐射（PAR）传感器，它价格低廉，且随着时间推移稳定性比一些PAR传感器中使用的干涉滤光片要好得多。绿色植物光合作用的作用光谱在蓝光和红光区域有主要峰值。在一项于1996年4月30日开始的正在进行的研究中，已使用在UV - A（380纳米）和红光（620纳米）区域有响应峰值的LED来测量接近太阳正午时的PAR。从1997年9月13日至2002年1月16日，来自两个LED的信号总和与经校准的无滤光片PAR传感器（Apogee QSO；犹他州洛根）的测量值高度相关（r2 = 0.97）。从1998年4月20日至2002年1月16日，LED信号总和与经校准的滤光片PAR传感器（LI - COR LI - 190SA；内布拉斯加州林肯）的测量值也高度相关（r2 = 0.97）。因此，成对的光谱选择性LED可在经济的PAR辐射计中用作PAR探测器。380纳米和620纳米的单独响应还允许评估气溶胶事件对蓝光和红光PAR以及向光辐射的不同影响。
