Photometers are specifically designed to measure emitted, reflected or transmitted light in photometric terms of luminous flux, luminance, illuminance or luminous intensity.

光度计是专门用于测量发射，反射或透射光的光通量，亮度，照度或发光强度等。

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Low light level TV is usually operated under extremely low illuminance or other adverse circumstances and the output SNR decreased to such a level that possibility of detection is greatly reduced.

微光电视工作于极低照度或恶劣环境下，输出信噪比明显降低，目标完全淹没在背景噪声中，使探测率大大下降。

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Experiments show that the guide has high light-transmitting efficiency that makes high illuminance at the end of the guide so that the surface of the guide is illuminated uniformly.

实验表明，无缝棱镜导光管能够以较高的效率传输光线，并将光线较为均匀地分布于传播路径。

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