共光路空间外差干涉仪理论与性能分析

介绍一种利用一块光栅兼作分束器和色散器的Ｓａｇｎａｃ型空间外差干涉仪的基本结构和原理,利用光波传播角谱理论详细分析给出此干涉仪形成的干涉图样和条纹定域位置。作为无动镜傅里叶光谱仪的干涉分光系统,阐明分光原理,给出理论仪器函数、无谱分辨极限和分辨本领、工作光谱范围、及光通量和视场等性能。指出它兼有传统傅里叶变换光谱仪和光学多通道分析仪（ＯＭＡ）的优点。     

Infrared laser heterodyne ozone spectrum

An infrared laser heterodyne spectrometer (IRLHS) has been developped for both laboratory and atmospheric studies. A long path and temperature adjustable cell has been designed for laboratory spectra. An ozone spectrum with 5MHz (0.00016 cm^?1) resolution is presented.     

Heterodyne spectrometer for the 10 micron region

We first consider the interest of infrared heterodyne spectroscopy to study the vertical distribution of atmospheric constituents such O₃. Then an heterodyne spectrometer is described. It operates in the 10 micron region with a CO₂ laser and gives a resolution of 5 MHz. A laboratory spectrum of C₂H₄ is presented as a preliminary result.     

Broadband acoustooptic spectrometer used as backend for remotesensing of trace gases in the atmosphere

A broad-band acoustooptical spectrometer was used as a backend of a millimeter wave heterodyne receiver to detect the rotational transition of ozone at 142.175 GHz. The AOS has a total bandwidth of 1.07 GHz covered with 1728 channels with 1.2 MHz resolution bandwidth each. The influence of the instrumental filter characteristic, linearity in power, stability in power and frequency, to the measurements and subsequent retrieval of atmospheric ozone profiles have been analyzed. Estimation of a linear slope and an offset brightness temperature has been included in the inversion process using the optimal estimation method     

Fast Holographic Image Reconstruction Using Phase‐Shifting Assisted Depth Detection Scheme for Optical Scanning Holography

For the implementation of a real‐time holographic camera, fast and automatic holographic image reconstruction is an essential technology. In this paper, we propose a new automatic depth‐detection algorithm for fast holography reconstruction, which is particularly useful for optical scanning holography. The proposed algorithm is based on the inherent phase difference information in the heterodyne signals, and operates without any additional optical or electrical components. An optical scanning holography setup was created using a heterodyne frequency of 4 MHz with a 500‐mm distance and 5‐mm depth resolution. The reconstruction processing time was measured to be 0.76 s, showing a 62% time reduction compared to a recent study.     

综合孔径微波辐射计二阶量化数字相关器研究

微波辐射计作为一种无源遥感器,在遥感技术领域有着巨大的应用前景.传统的微波辐射计的空间分辨率受到天线孔径的限制.综合孔径微波辐射计利用了干涉测量原理和复相关技术,是一种可以有效地提高空间分辨率的新型辐射计.本文针对综合孔径微波辐射计的数字相关器进行了深入研究,分析论证了二阶量化数字相关器的工作机理,并对采用该种相关器的系统的信噪比进行了分析.初步的试验验证结果证明了该方案的有效性.     

A low power digital controlled oscillator

A simple CMOS digital controlled oscillator (DCO) is developed for digital phaselock-loop and digital communication applications. The new DCO has a very simple structure with high linearity and resolution. For example, a four-bit DCO requires only fifteen MOS transistors. The new DCO has a tuning range from 15 MHz to 29 MHz. The maximum power consumption at 29 MHz is equal to 5.5 mW.     

A 9-V/Lux-s 5000-frames/s 512/spl times/512 CMOS sensor

A high-responsivity 9-V/Lux-s high-speed 5000-frames/s (at full 512/spl times/512 resolution) CMOS active pixel sensor (APS) is presented in this paper. The sensor was designed for a 0.35-/spl mu/m 2P3M CMOS sensor process and utilizes a five-transistor pixel to provide a true parallel shutter. Column-parallel analog-to-digital converter (ADC) architecture yields fast readout from pixels and digitization of the data simultaneously with acquiring a new frame. The chip has a two-row SRAM to store data from the ADC and read previous rows of data out of the chip. There are a total of 16 parallel ports operating up to 90 MHz delivering /spl sim/1.3 Gpixel/s or 13 Gb/s of data at the maximum rate. In conclusion, a comparison between two high-speed digital CMOS sensor architectures, which are a column-parallel APS and a digital pixel sensor (DPS), is conducted.     

A mixed-signal approach to high-performance low-power linearfilters

We present a new approach to the design of high-performance low-power linear filters. We use p-channel synapse transistors as analog memory cells, and mixed-signal circuits for fast low-power arithmetic. To demonstrate the effectiveness of our approach, we have built a 16-tap 7-b 200-MHz mixed-signal finite-impulse response (FIR) filter that consumes 3 mW at 3.3 V. The filter uses synapse pFETs to store the analog tap coefficients, electron tunneling and hot-electron injection to modify the coefficient values, digital registers for the delay line, and multiplying digital-to-analog converters to multiply the digital delay-line values with the analog tap coefficients. The measured maximum clock speed is 225 MHz; the measured tap-multiplier resolution is 7 b at 200 MHz. The total die area is 0.13 mm². We can readily scale our design to longer delay lines     

Antireflection coated, wedged, single-crystal silicon aircraftwindow for the far-infrared

Operating far-infrared remote-sensing instruments from inside a pressurized cabin of an aircraft requires a window with high transmittance. Furthermore, the radiometric properties of the window, such as the transmittance and the emitted radiation (i.e., temperature distribution), have to be known. The design of a wedged, antireflection coated single-crystal silicon aircraft window, its modeled transmittance spectrum, and the applied coating technique are presented. Measurements of the window transmittance with the 2.5 THz heterodyne spectrometer TeraHertz OH-Measurement Airborne Sounder (THOMAS) and a Fourier-transform spectrometer are presented, showing a transmittance of about 90% around 84 cm^-1. The window was designed and built for the 2.5 THz OH-Sensor THOMAS, operated on the DLR research aircraft FALCON. The transmittance of 90% means a substantial improvement compared to the window used previously. With this new window, systematic errors in the measured atmospheric radiance could be lowered, making the retrieval of atmospheric parameters easier. Several successful flights with the new window up to an altitude of 43000 ft have already been performed     

用于空间外差光谱仪光谱定标的窄线宽可调谐光纤激光器

针对星载CO2遥感探测空间外差光谱仪2.04 μm通道光谱定标的应用需求,研制了一台2.04 μm波段窄线宽波长可调谐的高稳定性铥钬共掺光纤激光器(THDFL).利用线型复合谐振腔的维纳效应扩大有效纵模间隔,有效抑制了多模激光振荡,输出激光线宽达7.5 MHz;通过对振动隔离和温度补偿封装的FBG施以轴向拉伸应力,该THDFL可在2040～2042.5 nm范围内调谐,且输出波长不确定度小于5×10-3 nm;使用研制的1565 nm光纤激光泵浦源,THDFL输出功率达192 mW;利用该可调谐THDFL提供的输出激光,溯源于波长标准后实现了空间外差光谱仪2.04 μm通道的光谱定标,且定标精度优于设定的指标要求.     

成像光谱仪的离轴反射式光学系统设计

高分辨率成像光谱仪要求光学系统在宽视场和宽波段范围内具有高的空间分辨率和光谱分辨率。根据同轴三反光学系统初级像差理论计算初始结构,并分别将孔径光阑置于主镜、次镜和三镜焦点,通过光阑和视场离轴,设计了无中心遮拦的离轴反射式光学系统。其光谱范围为1.0~2.5 m,焦距f=1 600 mm,相对孔径为1/ 5,视场角为6.861.48,满足成像光谱仪宽视场、大相对孔径离轴三反消象散光学系统的设计指标。     

A New Technique for Recording High-Voltage Transients in Telephone Networks

Some basic difficulties in the protection of telephone networks against dangerous overvoltage disturbances such as lightning are discussed, and a new method for measuring and recording such transients is presented. The method essentially consists of measuring the analog disturbance signals, converting and coding their temporal values into digital numbers easily available to shift register memories and subsequently recording the results either with a teleprinter for computer analysis and statistical abstracts or with axy-recorder for a human observer. The instrument is capable of recording disturbance amplitudes of 0.1-MHz spectral content linearly with an 300-V interval up to voltages of 5 kV, the sampling rate of the A/D converter used for the recording being adjustable to values of 500 kHz, 1 MHz or 2 MHz. The digital circuits of the instrument use positive logic and are realized for the most part by TTL and MOS technologies.     

采用相干技术的高分辨光谱检测系统设计

采用外差相干技术理论上可以获得低至MHz量级甚至更高分辨率的光谱信息。介绍了一种基于外差相干技术方法实现的光谱检测系统,并推导了90光学混频器和平衡探测器的信号传输原理,讨论了本振光和滤波器的性能参数与光谱检测分辨率的关系。利用光通信系统设计软件OptiSystem建立了完整的相干光谱检测系统的模型,并使用波长扫描和迭代运算模拟了实际本振光信号的工作模式,验证了该方案实现高分辨光谱分析的可行性和优越性。最后分析了对于频率间隔为40 MHz的被测信号,不同的本振光扫描线宽、扫描步长和滤波器带宽参数组合实现的仿真结果,并总结了光谱检测精度对本振光和滤波器等关键参数的要求。     

单频激光宽频段频率和强度噪声测量技术

报道了一种mHz至MHz宽频段激光噪声的规范测量技术。通过研制基于迈克耳孙光纤干涉仪的相关延时自外差频率噪声测量装置和具有定标功能的光外差拍频测量装置,结合频谱分析仪和快速傅里叶变换分析仪等标准仪器,规范地测量出了单频激光在mHz至MHz宽频段内的频率和强度噪声特性,并验证了测量结果的准确性。该测量技术有望应用于引力波探测和精密测量等应用中的激光噪声评估。     

空间外差光谱仪干涉图修正研究

空间外差光谱技术（Spatial heterodyne spectroscopy, SHS）是一种新型的光谱分析技术,本文基于空间外差光谱仪的基本原理和特点,研究了实际测量中干涉仪两光臂不平衡造成的畸变干涉图的修正方法,模拟计算了干涉仪两光臂不平衡时干涉图的强度变化,并对其进行了模拟修正,修正后的干涉图与理想的SHS干涉图一致性较好。修正方法主要是测量干涉图的非调制项（即未发生干涉时单个光臂的光强）,以及在干涉图数据处理中引入了一个修正因子。通过对干涉仪两臂不平衡的修正,可以有效地提高干涉图反演光谱的精度。     

The Long Wavelength Array

The Long Wavelength Array (LWA) will be a new multipurpose radio telescope operating in the frequency range 10-88 MHz. Upon completion, the LWA will consist of 53 phased array ldquostationsrdquo distributed over a region about 400 km in diameter in the state of New Mexico. Each station will consist of 256 pairs of dipole-type antennas whose signals are formed into beams, with outputs transported to a central location for high-resolution aperture synthesis imaging. The resulting image sensitivity is estimated to be a few millijanskys (5 sigma, 8 MHz, two polarizations, 1 h, zenith) in 20-80 MHz; with resolution and field of view of (8 ^', 8^deg) and (2^', 2 ^deg) at 20 and 80 MHz, respectively. Notable engineering features of the instrument, demonstrated in this paper, include Galactic-noise limited active antennas and direct sampling digitization of the entire tuning range. This paper also summarizes the LWA science goals, specifications, and analysis leading to top-level design decisions.     

High frequency stability of laser diode for heterodyne communication systems

The emission frequency of a single-mode GaAlAs laser diode was locked to a Fabry-Perot interferometer reference by using a high sensitivity and fast response feedback loop controlling the injection current. Long-term fluctuations have been reduced to 8 MHz with a short-term jitter less than 1.5 MHz. These figures are consistent with the requirements of heterodyne communication systems above 140 Mbit/s.     

彩色大面阵数字航空遥感相机技术的研究

提出了一种以彩色大面阵CCD探测器作为成像介质的大视场数字航空摄影相机设计技术。采用对称Russar型光学系统,在获得了大视场角的同时最大程度的降低了光学畸变;设计了精确的微位移传动系统移动CCD探测器以补偿前向像移,提高了相机的动态分辨率;设计了一种双叶片的中心式机械快门,获得了宽范围的曝光时间控制,保证了探测器的均匀曝光及合适的图像重叠率。地面及空中成像测试中相机的静态分辨率达到了CCD特征频率的要求,获得了清晰的航拍彩色图像,表明相机的各项技术性能满足要求,该相机技术已应用到国土资源的遥感普查中。