Y-type calibration optical path of cryogenic radiometer

（Imaged by PANG Weiwei）

Recently, A research reported that researchers designed a novel calibration optical path by placing the standard transfer detector in a Y-shape vacuum unit. This design theoretically eliminated the uncertainty caused by window transmittance. This study was conducted by Prof. ZHENG Xiaobing, Dr. PANG Weiwei and their study team. And the design entitled "Novel Calibration Optical Path of Cryogenic Radiometer " was published in Chinese Optics Letters.

It has been demonstrated that reflectance and scattering effect of Brewster window plays a significant role in characterizing absolute power of laser. As to the successive calibration in wide spectrum, the wavelength of the output beam from the tunable laser varies with polarization state. Thus it is essential to accurately measure and adjust the polarization state in different wavelengths repeatedly. However, the workload of this traditional experimental scheme is too large and meanwhile low repeatability of the optical path aggravates uncertainty.

In this study, a fine instrument with automatic reset technology was used to increase the accuracy of the cryogenic radiometer and transfer detector switching into the optical path, which decrease the uncertainty caused by spatial non-uniformity. Two calibration optical paths, covering visible and infrared spectrum respectively, have been established in a Y-shape vacuum chamber, in which beam shaping, spatial filtering power stabling, and stray light suppression technology were put into use. Such a design can be used as a new calibration technique for successive calibration in broad spectrum. And this research result becomes a powerful support for the quantitative traceability of radiation standard.

Contact:

Prof. ZHENG Xiaobing

Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences ，

P.O. Box 1125, Anhui, Hefei 230031, P.R. China

Tel: +86-551-65595330

E-mail:xbzheng@aiofm.ac.cn