Precision of a Low-Cost InGaAs Detector for Near Infrared Photometry
Precision of a Low-Cost InGaAs Detector for Near Infrared Photometry
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用于近红外光度测定的低成本 InGaAs 探测器的精度
DOI：
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发表时间：
2013
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通讯作者：
R. Simcoe
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作者：
P. Sullivan;B. Croll;R. Simcoe
我们已经设计、建造并测试了InGaAs近红外相机，以探索低成本探测器是否可以制造小型（≤1米）望远镜，能够对相对明亮的目标进行精确（< 1毫米）的红外测光。该相机围绕由FLIR光电元件公司制造的640 × 512像素APS640C传感器构建。我们设计了定制的模数电子设备，以实现最大的稳定性和最小的噪音。每冷却7°C， InGaAs暗电流就会减半，通过将阵列冷却到-20°C，我们将其降低到840 e- s-1像素-1（像素间的变化为±200 e- s-1像素-1）。超过这个点，读出的光占主导地位。单样本读取噪声149e -通过上行采样降低到54e -。实验结果表明，在2.4 × 104 e- s-1的通量下，双星差分光度测量的精度可达631±205 ppm (0.68 mmag) hr-1/2。采用三颗比较星和去相关参考信号进一步将精度提高到483±161 ppm (0.52 mmag) hr-1/2。对HD80606和HD80607 （J = 7.7和7.8）在Y波段的光度观测表明，在0.25 m的有效口径下，差分光度测量精度达到415 ppm (0.45 mmag) hr-1/2。下一代InGaAs探测器确实应该能够对较亮的矮星进行泊松限制光度测定，特别是对m晚期和L型矮星。此外，人们可以同时进行近红外光度测量和光学光度测量或径向速度测量，以最大限度地利用小型望远镜进行系外行星搜索。
We have designed, constructed, and tested an InGaAs near-infrared camera to explore whether low-cost detectors can make small (≤ 1 m) telescopes capable of precise (< 1 mmag) infrared photometry of relatively bright targets. The camera is constructed around the 640 × 512 pixel APS640C sensor built by FLIR Electro-Optical Components. We designed custom analog-to-digital electronics for maximum stability and minimum noise. The InGaAs dark current halves with every 7°C of cooling, and we reduce it to 840 e- s-1 pixel-1 (with a pixel-to-pixel variation of ± 200 e- s-1 pixel-1) by cooling the array to -20°C. Beyond this point, glow from the readout dominates. The single-sample read noise of 149 e- is reduced to 54 e- through up-the-ramp sampling. Laboratory testing with a star field generated by a lenslet array shows that two-star differential photometry is possible to a precision of 631 ± 205 ppm (0.68 mmag) hr-1/2 at a flux of 2.4 × 104 e- s-1. Employing three comparison stars and decorrelating reference signals further improves the precision to 483 ± 161 ppm (0.52 mmag) hr-1/2. Photometric observations of HD80606 and HD80607 (J = 7.7 and 7.8) in the Y band shows that differential photometry to a precision of 415 ppm (0.45 mmag) hr-1/2 is achieved with an effective telescope aperture of 0.25 m. Next-generation InGaAs detectors should indeed enable Poisson-limited photometry of brighter dwarfs with particular advantage for late-M and L types. In addition, one might acquire near-infrared photometry simultaneously with optical photometry or radial velocity measurements to maximize the return of exoplanet searches with small telescopes.