Development of a Cryogenic Infrared Camera with a Wide Field of View

低温红外相机的发展所需的元件分为三类：低温，光学和电子学。设计并制造了一台大开口的低温恒温器。尽管大量的热量从窗口进入，但通过使用闭合循环冷却器，整个光学系统可以保持在80 K以下，并且检测器单元可以保持在30 K以下。采用铟封和铜线改善热传导，有效地将热量从冷却头中排出。低温发动机是由普通的商用发动机通过更换轴承制成的，它们的试验已经确定了它们在液氮温度下的运动。首先，制作了几个小的测试镜：偏置抛物面镜、直径为10厘米的抛物面镜和直径为15厘米的球面镜。所有这些都被证明具有足够的准确性。采用Ritchey-Chretien光学系统作为主镜和次镜。设计并制造了初级（直径25 cm）和次级。同时还制造了用于像差校正的两件式透镜。完成了测试电子学，显示出足够低的噪声。MESSIA-III（日本国家天文台）将作为独立于探测器的部分使用，上述三个要素将被整合，今年将开始用它观测银河平面。

Elemnts required for the development of the cryogenic infrared camera were divided into three categories : cryogenics, optics, and electronics. Each development is nearly completed.A cryostat with a large opening was designed and manufactured. Despite of large heat coming in from the window, the whole optics can be maintained below 80K and the detector unit below 30K,by using a closed cycle cooler. Indium seal and copper wires were employed to improve heat conduction and expel the heat from the cooler head efficiently. Cryogenic motors were made out of usual commmerical motors be changing bearings, and their tests have established their motion at the liquid nitrogen temperature.Metal mirrors were manufactured and examined. First, several small test mirrors were made : offset parabolas, parabolas of 10 cm in diameter, and spherical mirrors of 15 cm in diameter. All of them turned out to have sufficient accuracy. A Ritchey-Chretien optics was adopted as the primary and secondary mirrors. The primary (25 cm in diameter) and secondary have been designed and manufactured. Two-pieceens for aberration correction was also manufactured.Test electronics was completed and shows sufficiently low noise. MESSIA-III (National Astronomical Observatory of Japan) will be used as detector-independent part.The above three elements will be integrated, and observation of the Galactic plane with it will be started this year.