Linear Avalanche HgCdTe Arrays for Photon Counting AO Wavefront Sensing

自20世纪90年代中期以来，自适应光学（AO）技术已经彻底改变了光学和红外（IR）波长的地面观测天文学。精确地感知来自自然恒星或激光导星的大气波前畸变对于达到望远镜的衍射极限至关重要。夏威夷大学的Donald Hall博士建议，通过国家在空间和军事雷达上的大量投资，通过生产适度格式阵列和展示其用于望远镜波前传感的光子计数性能，来适应和优化AO波前传感传感器。为了实现这一目标，该技术利用了HgCdTe独特的线性雪崩特性，这种物质已经成为天文学在1 - 5微米波段的首选材料，也是近红外天文学生产大格式阵列的技术基础。该项目将杂交32 × 32 HgCdTe线性模式雪崩光电二极管阵列，以优化64输出读出。这些杂交体将以高量子效率计算波长在0.85到2.5微米之间的单个近红外光子，帧率接近100 KHz，并且不会降低其基本泊松统计量。目标是生产超过一千个读出芯片，并制作几十个高质量的杂交阵列，用于望远镜AO系统的初始表征和部署。虽然拟议的研究有可能彻底改变AO波前传感及其在地面望远镜上实现的科学的各个方面，但它几乎没有触及天文学以外的更广泛应用的表面。这项调查还将包括潜在的太阳能应用，并可能使日冕物感测成为可能。最后，社会将受益于这项技术的发展，它在天文学以外的应用，以及它将使令人兴奋的科学发现成为可能。美国国家科学基金会天文科学部通过其先进技术和仪器项目为原型光谱仪的开发和建造提供资金。

Since the mid 1990's, Adaptive Optics (AO) techniques have revolutionized ground-based observational astronomy at optical and infrared (IR) wavelengths. The precise sensing of the atmosphere's distortion of the wavefront from a natural or laser guide star is crucial to achieving a telescope's diffraction limit. Dr. Donald Hall of the University of Hawaii proposes to adapt, and optimize for AO wavefront sensing, sensors developed through the nation's substantial investment in space and military LADAR by producing modest format arrays and demonstrating their photon counting performance for wavefront sensing at the telescope. To achieve this, the technique utilizes the unique linear avalanche properties of HgCdTe, a substance already the material of choice for astronomy in the 1 - 5 micron waveband and the technology base for production of large format arrays for near-IR astronomy. The project will hybridize 32x32 arrays of HgCdTe linear-mode avalanche photo-diodes to an optimized 64-output readout. These hybrids will count individual near-IR photons with wavelengths between 0.85 and 2.5 microns with high quantum efficiency, at frame rates approaching 100 KHz, and with no degradation of their fundamental Poisson statistics. The goal is to produce over a thousand readout dies and to make several dozen high-quality hybridized arrays available for initial characterization followed by deployment in telescope AO systems.While the proposed investigation has the potential to revolutionize AO wavefront sensing and all aspects of the science it enables on ground based telescopes, it barely taps the surface of broader applications that extend beyond astronomy. The investigation will also encompass potential solar applications and likely enabling coronal AO sensing. Finally, society will benefit from the development of the technique, its application beyond astronomy, and the exciting scientific discoveries it will make possible.Funding for development and construction of the prototype spectrograph is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.