库存数量:
产品介绍:初级标准低温辐射计系统
NPL's cryogenic radiometer is the primary standard for the measurement of optical radiant power. It uses the electrical substitution technique, whereby the optical power incident on an absorbing cavity is compared with the electrical power required to heat the cavity to the same temperature. High Tc superconducting leads to the cavity heater ensure true equivalence of electrical and optical power.
The cavity is made of electroformed copper to reduce its mass and is coated internally with NPL super black. The design of the cavity in combination with operation at helium temperatures ensures an optimal response to incoming radiation. The cavity is isolated from fluctuations in the cold head of the cooler by a reference block maintained at a constant temperature. The accuracy of the system is further enhanced by operating the cavity within an isothermal shield.
The thermal link between the cavity and reference block is designed to optimise the temperature rise for a specific power level. A balance is achieved between the need for a high impedance to maximise the sensitivity and the need for a short time constant. This link is adjustable but is set at the time of order.
Purchasing a cryogenic radiometer allows a laboratory to establish their own scales traceable to a primary standard. These scales are usually disseminated using trap detectors as a transfer standard and solid state working standards. The cryogenic radiometer is used with a variety of laser sources.
工作环境要求 | |
工作温度 | 12 K |
绝对精度 | ± 0.005 % |
电源供电 | 220 V - 240 V, 50 Hz, 1.9 kVA 208 V - 220 V, 60 Hz, 2.0 kVA |
Cold head service interval | > 15 000 hours |
Absorber service interval | 15 000 hours |
Water cooling水冷系统 | 3 l/min minimum at 20°C |
Radiometric Properties辐射计性能指标 | |
Receiver response接收机响应 | 1.2 K/mW approximately |
Maximum power最大功率 | 2 mW |
Resolution at maximum power分辨率@最大功率 | 1 in 105 |
Time constant 时间稳定性 | 70 seconds |
Brewster window transmission | 400nm to 800nm 99.96% |
Cavity Absorption吸收率 | 200nm to 2000nm >99.99% |
其他选项 | |
Vacuum pumping station | The detector comparitor stage |
Detector comparator stage | |
Laser stabilisation facility | |
Brewster window assembly optimised for mid infrared use | |
Brewster window transmission measurement system |