photounitn.光电元件photon.照片v.拍照photocounting distribution光电计算分布photo slit lamp microscope照相裂隙灯显微镜photovoltaic power systems光伏系统photoelectric spectrometer光电分光计,光电频谱仪photoelectric dark current光电暗电流photo-dissociation laser光致离解激光器photovohaie electric power太阳能直接利用photoionization ion source光致电离离子源photoconductivity spectrum光电导光谱photo-electricity tracer光电跟踪仪