Time: 10:30-11:30am 17 Sep., 2012(Monday)
Location: Conference Room 440, the 3rd Academic Building, Yuquan Campus, Zhejiang University
New method for high-accuracy calibration of optical sensors using a low-cost tunable kHz OPO laser system
Abstract:
Continuous-wave (CW) and pulsed, mode-locked tunable lasers have been successfully used for calibration of optical sensors, especially for spectral irradiance and radiance responsivity, for many years at NIST and other National Metrology Institutes to achieve smallest calibration uncertainties. These tunable lasers, however, are expensive and difficult to automate; these characteristics limit their widespread use. To address these issues, a new method was developed recently at NIST for calibration of optical sensors using a low-cost, fully automated kHz pulsed tunable optical parametric oscillator (OPO) laser system with a continuously tunable range from 210 nm to 2400 nm. Unlike conventional methods, the new method is based on measurement of total energy of a pulsed OPO laser train using two synchronized current integrators (also called charge amplifiers) to obtain total integrated electric charges from a test detector or standard detector and a monitor detector, respectively. Extremely high measurement repeatability (10 ppm) is achieved by using this new method even though fluctuation of the OPO laser is approximately 10 %. Absolute expanded calibration uncertainty is estimated to be 0.05 % (with a coverage factor of k = 2), which is virtually the same as that by using tunable CW lasers. The calibration method, the kHz OPO laser system, and various applications will be discussed.
Brief Bio:YuqinZong graduated in 1984 from the Department of Optical Engineering, Zhejiang University. He received his Master of Science degree in high-speed photography in 1987 from the Institute of Optics & Electronics, Chinese Academy of Sciences, Chengdu. From 1987 - 1994, he was with the Shanghai Institute of Technical Physics, Chinese Academy of Sciences, working on meteorological satellite projects. Currently Yuqin is an electronics engineer at the Sensor Science Division, Physical Measurement Laboratory, National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, USA. His job responsibility includes realization and maintenance of the NIST photometry and colorimetry scales and providing calibration services to the industry. His research covers areas such as stray-light correction for array spectrometers and imaging instruments, measurement of high-power LEDs and solid-state lighting (SSL) products, and calibration of detectors using tunable lasers Yuqin is the chairman of technical committee TC2-63 of the International Commission on Illumination (CIE) for Optical Measurement of High-Power LEDs. He is also the chairman of the working group of the Illuminating Engineering Society (IES) for measurement of AC LEDs.