| Popis: |
A measuring system for the cutoff depth of out-band of solar blind UV filters with a large dynamic range is proposed by using narrow-band Light Emitting diode (LED) lights as the standard light source. The measuring error of the system is also analyzed. The system consists of LED light sources, the standard reflective neutral attenuators known attenuation coefficients and a photomultiplier. Based on substitution method, the photomultiplier detects the current of the LED through the attenuator as reference to substitute LED initial current, thus the cutoff depth of the out-band of filters is acquired. For the reflective attenuator in the system, an attenuator combination method is presented to insure the photomultiplier working continuously within a linear response range. Experimental results show that the cutoff depth of the out-band of filters is measured to 11-OD in the large spectral range of 350-800 nm. Furthermore, the uncertainty is less than 2% and the relative repeatability error is less than 0.2%. The measuring system has a simpler structure, higher precise, a large spectral range and a wider dynamic range and has been widely used in the measurement of the filter cutoff depth of filters. |
