The Research Of Measurement Technique About Spectral Radiation Parameters

The metrology of optical radiation is the most elementary part in optic metrology. This paper is mainly relative to three parameters1 measurement, which are spectral irradiance, spectral radiance and colour temperature. The metrology of these parameters plays an important role in moder war. With the development of infrared detection technique, infrared technique is firstly applied in military department because it provides the possibility to observe, detect military target in darkness and communicate in a secure way. We usually must know radiance of the image formed by optical system in infrared optical system applications. In order to assess property of infrared optical system we must know radiance of image also. In the regions of astrodome physics, solid physics, photochemistry and medicine, measurement and calibration of spectral irradiance of ultraviolet and vacuum ultra-violet have become more and more important research means and instrument. The measurement of colour temperature is important to bulb industrial and illumination engineering.Before 1990, more than a dozen of overseas nations had founded the standard of spectral irradiance and spectral radiance in succession. The standard of spectral irradiance and spectral radiance in this country founded in 1980s has not met the measurement accuracy required by the research development of national defence. So it is very important to found a higher accuracy standard of spectral irradiance and spectral radiance.The article begins with the conclusion of measurement approaches on spectral irradiance, spectral radiance, colour temperature and blackbody temperature and introduces measurement approach, theory, system and signal measurement technique systematically. The measurement system is made up of optical system, comparison system, control system and cooling system In the course of the temperature measurement of high temperature blackbody, we use filter radiometer that is a new approach to measure radiation temperature. The approach was adopted by PTB, NPL and VNIIOFO in 1997 when they made international comparisions of spectral irradiance. The approach is that we firstcalibrate the filter radiometer with cryogenic radiometer and measurement equipment of relative spectral responsivity and then calculate the absolute spectral responsivity. Because the drift in blackbody temperature directly influnces measurement accuracy, so we adopt a feedback system to stabilize blackbody temperature through controlling the current of blackbody that improves measurement accuracy greatly. In order to realize the measurement of several parameters and broad-band spectrum(250nm~3000nm) on the same standard equipment, we make use of two main light paths. One is to measure spectral radiance, the other is to measure irradiance through integral sphere, translational stage and mirror changing the light path. The standard equipment is a large and complex system including radiation standard, radiation transfer standard and comparison equipment. In the course of founding the standard equipment, we apply infrared technique, laser technique, weak signal detection technique, precision machining and computer technique. In order to meet the requirements of uncertainty, we need not only know the property of all apparatus but also precisely debug software, tune electric signal and light path to achieve optimal combination in every wavelength.In conclusion, we accomplish the project successfully and realize optimal combination of apparatus through our diligent work.