SQUID与半导体样品的无损检测

随着半导体集成度的不断提高，半导体检测技术也不断拓展和更新。SQUID是目前所知的最灵敏的磁场和磁通探测器。本文将介绍一种以SQUID为探头的、非接触式的、半导体材料和器件检测装置。     

复合材料无损检测与光纤传感器

本文讨论了复合材料测试特点,介绍了光纤传感器原理及特点,重点讲述光纤传感器在复合材料无损测试中的应用。     

无损检测机构的质量管理分析

由于科学社会的不断发展与进步,人们对无损检测机构的质量要求越来越高,而无损检测机构也是社会十分重视的,因为它影响着无损检测机构的投入融资和经济效益,所以要不断的提高无损检测机构的质量管理,要把对无损检测机构的质量管理作为首要任务。随着无损检测机构的不断发展,无损检测机构的质量管理方式也在不断的改革,在新的改革中把无损检测机构的质量放在了首位,虽对此进行了一些改革措施,但依然不能避免一些问题的发生,所以要重视对无损检测机构的质量管理,这有这样才可以确保产品质量获得有效的控制,从而不断加强无损检测本身的质量。     

半导体无损检测仪器

我国唯一能对半日导体器件实现无损检测的仪器——光调制反射显微镜，由南京大学信息物理系专家研制成功，目前，我国半导体器件检测，是将半导体集成电路板上的所有元件折下来，把扳上铝箔之类的焊接材料溶解，这样，检测后的电路板就被损坏了。现在用光调制反射显微镜，     

无损检测在木材应用中的现状及发展趋势

无损检测技术在木材检测中的地位日益重要,本文主要从应力波检测、超声波检测、X射线检测和机械应力检测四个方面介绍了无损检测在木材中的应用,阐述了其基本原理和特点,概述了发展历史和研究现状,并展望了未来研究方向及工作重点。     

浅谈压力容器的无损检测

随着科技的不断进步、经济的不断发展,对产品的质量和产品的安全状况以及使用的性能都提出了很高的要求。由于无损检测不但检查的灵敏度高,而且还具有不损伤材料不破坏试件等许多优点,因此,此检查方法得到越来越广泛的应用     

桩基质量和承载力的无损检测

本文应用振动理论,分析了解态锤击法对桩基质量和承载力无损检测的原理和方法,讨论了可靠准确检测桩基的几个实用技术问题和测试仪器的合理配置。     

陶瓷涂层的无损检测

无损检测可避免有损检测带来的使用安全隐患,这是一种值得推广应用的技术.为此,介绍了陶瓷涂层常见缺陷种类及产生原因,阐述了陶瓷涂层无损检测的几种重要方法的基本原理以及目前国内外在这方面的研究现状.     

高温超导量子干涉器在无损检测中的应用研究

研制了一套可长时间稳定工作在无屏蔽环境中的高温超导量子干涉器(SQUID)无损检测装置,其中SQUID由Yba2Cu3O7(YBCO)制成,为了减小低频噪声,SQUID器件采用多圈条形结构,膜条宽度8pm,膜条间隔10pm,器件的有效面积为0．01mm^2,在无屏蔽环境中的磁通白噪声约为200μφ0／（Hz的平方根）,利用该装置对有内部缺陷的铝样品进行了电磁无损检测实验研究,并对激励频率与缺陷深度、缺陷大小与信号响应之间的关系进行了初步的探讨。     

High Dynamic Range SQUID Readout for Frequency-Domain Multiplexers

A 16-SQUID array has been designed and fabricated, which shows 0.12 μΦ ₀ Hz^−1/2 flux noise at 4.2 K. The readout amplifier based on a cryogenic silicon-germanium bipolar transistor employs short-delay negative flux feedback and reaches 7 MHz bandwith for a 1 Φ _0p-p signal. The −1 dB compression is reached approximately at 4.2 Φ _0p-p amplitude when the signal frequency is 1 MHz. In the feedback mode the flux noise is anomalously increased to 0.35 μΦ ₀ Hz^−1/2.      

SQUID生物磁图仪

简述了生物磁测量原理、测量难点以及国内外水平．着重提出了开展这一研究的相关的关键技术，并提出了今后开展这一研究工作的建议。     

Performance of a 2-hole Y-Ba-Cu-O rf SQUID

A two-hole rf SQUID has been fabricated out of bulk YBCO by drilling two holes and careful erosion of the wall between the holes. Commercial SQUID electronics is inductively coupled to the SQUID through a copper coil glued in one of the holes. Periodic oscillations in V-B characteristic of the SQUID are observed at 77 K. The spectral density of the flux noise in the white noise region is 5·5 × 10⁻⁴Φ₀ / √Hz. The flux noise is frequency-dependent below 200 Hz.     

Development of High-T c SQUID System for Nondestructive Evaluation

Nondestructive evaluation (NDE) system with high spatial resolution power based on high-T _c superconducting quantum interference device (SQUID) has been developed. The SQUID is fabricated by YBCO thin film and mounted in vacuum at the end of a cold finger fixed at the inner wall bottom of the dewar, which is filled with liquid nitrogen (77 K) to cool the SQUID sensor. The sensor faces a thin flat sapphire window on the outer wall of the dewar and is thermally isolated from it by a vacuum space at a distance of less than 1 mm. The magnetic field sensitivity of SQUID is about 40 pT/ Hz in magnetically unshielded environment. This NDE system was used to detect the flaws buried into materials. The remnant magnetic field inducted by the local damages in a stainless steel sample was measured. Incorporated a gradiometric double-D excitation coil, the eddy current NDE was carried out. Small cracks in the aluminum below the surface can be detected effectively in unshielded environment.      

Design and characteristics of HTSC SQUID magnetometer with a sensitivity of 10−13 THz−1/2

The results are presented of the experimental studies on forming weak links in yttrium ceramics by scribing and high-voltage discharge. The energy resolution of SQUIDs and the magnetic field sensitivity of magnetometers produced according to these methods were 6×10⁻²⁸ J/Hz and 10⁻²⁸ J/Hz, 5×10⁻¹³ T/Hz^1/2 and 2·5×10⁻¹³ T/Hz^1/2, respectively. Different designs of HTSC interferometers sensitive to the external magnetic field variation are described. The factors affecting the sensitivity of r.f. HTSC SQUID-magnetometers are considered.     

Recent Results of a New Microwave SQUID Multiplexer

We present recent results of a prototype microwave SQUID multiplexer containing four SQUIDs coupled to GHz frequency resonant circuits and fed with a single microwave readout line. The system is operating at a readout frequency range of 8–10 GHz. All four SQUIDs share a common DC bias and modulation lines. A new modulation scheme is tested to eliminate the need for individual flux biasing of the SQUIDs, which extends the dynamic range of the readout. In this scheme a common modulation signal is imposed on each SQUID and the received signal is demodulated at one and two times the modulation frequency to maintain sensitivity at any flux state. We also demonstrated a microwave RF bias scheme eliminating the necessity of the DC current bias to the SQUID. Our preliminary performance tests at 4.2 K show that the input noise of the device is ∼5 pA/ .      

A TDMA Hybrid SQUID Multiplexer

We have developed a multiplexed read-out for transition-edge sensors (TES) based on a hybrid time- and frequency-domain basis set, similar to that used in time-division multiple-access (TDMA) mobile phones. The hybrid basis set uses bandwidth more efficiently than microwave frequency-division SQUID multiplexing, making it possible to multiplex more detectors in each output line. The high open-loop bandwidth provided by our SQUID TDMA system also makes it possible to multiplex large arrays of fast, high dynamic range detectors such as fast x-ray calorimeters. In this approach, we embed the second-stage SQUID amplifier of our standard time-division multiplexer in an impedance matching circuit coupled to a broadband cryogenic high electron mobility transistor (HEMT) in a microwave reflectometer configuration. The input signals are flux coupled into the first-stage SQUID amplifiers whose signals are time-division multiplexed into the second-stage SQUID. At room temperature, the signal from the HEMT is mixed down to dc for analysis and further signal processing.      

Construction and test of a cryocooler-cooled low-Tc SQUID gradiometer system

A cryocooler-cooled low-Tc SQUID gradiometer system was designed and constructed. It is based on a 4 K GM-cooler that is positioned several meters from the measuring head containing the SQUID sensors. The cooling power is transported by means of a circulating helium flow. Thus, there are three main components: the cooler vessel, the measuring head and the connecting flow-line.In stable operation, the SQUID and gradiometric pick-up loop are about 4.3 K. The overall heat loads to the cooler 1st and 2nd stages are estimated at 17 W and 0.3 W, respectively. The overall system noise was about 10 fT/√Hz although a number of peaks were observed in the spectrum. As an example, an adult heart beat was recorded.