兴隆60 cm望远镜主焦CCD系统测光性能的研究

对兴隆６０ｃｍ望远镜主焦ＣＣＤ系统的测光性能进行了测试和研究．测定了ＣＣＤ快门时间函数，讨论了快门延迟效应对短时间曝光观测的可能影响．通过观测大批Ｌａｎｄｏｌｔ标准星，较准确地定出了ＢＶＲＩ宽带测光的星等系统转换关系，结果表明本系统与标准ＢＶＲＩ系统很接近．对ＣＣＤ系统的天文测光精度作了仔细的检验和分析。

云南天文台RCA512×512 CCD系统的性能补充

云南天文台 1米镜于 1 993年安装使用了RCA 5 1 2× 5 1 2CCD(2号CCD) ,1 998年 5月对它的某些测光性能做了补充测定 ,包括 :本底场及其图案 (pattern)的变化 ;增益与读出噪音 ;线性 ;

Optical molecular imaging for detection of Barrett's-associated neoplasia

Recent advancements in the endoscopic imaging of Barrett's esophagus can be used to probe a wide range of optical properties that are altered with neoplastic progression.This review summarizes relevant changes in optical properties as well as imaging approaches that measures those changes.Wide-field imaging approaches include narrow-band imaging that measures changes in light scattering and absorption,and autofluorescence imaging that measure changes in endogenous fluorophores.High-resolution imaging approaches include optical coherence tomography,endocytoscopy,confocal microendoscopy,and high-resolution microendoscopy.These technologies,some coupled with an appropriate contrast agent,can measure differences in glandular morphology,nuclear morphology,or vascular alterations associated with neoplasia.Advances in targeted contrast agents are further discussed.Studies that have explored these technologies are highlighted;as are the advantages and limitations of each.

Liquid Drop Measuring Device for Analyzing Liquid Properties

Based on the correlation between certain properties of liquid and the properties of the corresponding liquid drop formed under given conditions, a liquid drop measuring device is utilized to monitor the drop formation process of the liquid sample with photoelectric measuring methods. The mechanical and optical characteristic of the liquid is explored with the optical fibers from the internal of the liquid drop during its formation. The drop head capacitor is utilized to monitor the growth process of the liquid drop to gain the drop volume information related to the physical property of liquid. The unique liquid drop trace containing the integrated properties of liquid is generated, and it is proved by experiment that for different liquids their liquid drop traces are different. The analysis on liquid properties and discrimination between different liquids can be proceeded with the liquid drop trace obtained by the liquid drop measuring device.

Bending Modulus Measurement of Single High Performance Fiber

The bending modulus property of high performance fiber is an important property for both polymer science and engineering. The measurement of the bending performance is, however, difficult because of the thin size of the fiber. We have measured this property by the axial compression bending method where single fiber with suitable slenderness is compressed in the fiber axial direction to obtain the peak point of the force-displacement curve. Then the bending modulus and the flexural rigidity can be calculated by measuring the protruding length and diameter of fiber needles and the critical force, Pcr. The measured data show that the bending characteristics of all kinds of high performance fiber are dissimilar evidently.

A Method of Peak Detecting for Nanosecond Pulse in Optical Performance Monitoring System

In optical performance monitoring system,the analog to digital converter is needed to detect the peak of nanosecond pulse and get the signal envelope.A scheme based on a designed anti-aliasing filter and analog to digital converter is proposed to broaden the nanosecond pulse and make it easier for the analog to digital converter to catch the peak of the nanosecond pulse.The experimental results demonstrate that,with the proposed scheme,the optical performance system needs less time to get the recovered eye-diagram of high speed optical data signal,and is robust to phase mismatch in the analog to digital converter circuit.

An Apparatus for Assessing Lustre of Fabrics

Luster is one of the main factors in assessing fabric appearance. There are many different ways to definite and describe the luster, which result in disorder and discommodious in evaluation. Based on previous work, an apparatus suited for the measure of lustre is developed. Which performed measure the reflection distribution of fabrics automatically. Then the objective judgment can be given by the geniophotometric curve. Finally taking several kind of specimens for example give the results to prove the effectiveness of the device.

Modified Fisheye Optical System

A design for a fisheye optical system is modified in order to enable IR vision in addition to the visible and UV lighting. The proposed modification goes to replace the optical material of the movable lens by another with less thermal dispersion. The choice of appropriate materials lead to a good focus appeared on the retina for a wide spectral range includes UV, visible, and near IR lighting. Then, the performance of the modified design is verified through some optical measures for imaging quality determinations. These optical measures are determined with the aid of Zemax software, which also used for testing performance of the modified fisheye optical system. The analysis mainly focuses on the energy distribution in the light spot on the focal surface. The results show that the modified design of the fisheye is acceptable.

Identification and Mutagenesis of Lactic Acid Bacteria from Chinese Sauerkraut

In order to analyze the fermentation properties of lactic acid bacteria in Chinese sauerkraut and to improve acid production, 21 samples of Chinese sauerkraut from Inner Mongolia and Northeast China were collected and isolated with a Man-Rogosa-Sharpe （MRS） culture. Sixteen strains of lactic acid bacteria were identified by combining both phenotype and genotype methods. After activation, the 16 strains were inoculated into the MRS medium with a concentration of 4% and then incubated at 37 ~C. The pH and the absorbance of the culture were mea- sured. The activated strains were then mutagenized in a field of 4 KV/cm mutation, with dosages administered within 20 minutes and 30 minutes, respectively. The variation curves of the pH and the absorbance of the culture were determined. The experimental results showed that the lactic acid bacteria isolated from the soup were identified as Lactobacillus and the acid production of the bacteria was signifi- cantly improved by the mutagenesis of the corona electric field.

Analysis of I-V Thermal Characteristic on GaN-based p-i-n Ultraviolet Detector

The I-V characteristic of GaN-based p-i-n ultraviolet detector is presented. It is measured at different temperatures and analyzed with changing temperature. The ideality factor of the device is 2.09 at room temperature. The maximum ideality factor is 2.14 at 100 ℃, which declines above 100 ℃, and the minimum ideality factor is 1.26 at 300 ℃. The coefficient of forward voltage vs. temperature is -1.97 mV/℃ with a forward current of 1 mA. Based on double injection model, the deep lying impurity activation energy in the i-region is 0.1 343 eV.

High-performance Ge p-i-n photodetector on Si substrate

High-performance and tensile-strained germanium （Ge） p-i-n photodetector is demonstrated on Si substrate. The epi- taxial Ge layers were prepared in an ultrahigh vacuum chemical vapor deposition （UHV-CVD） system using low tem- perature Ge buffer technique. The devices were fabricated by in situ doping and using Si as passivation layer between Ge and metal, which can improve the ohmic contact and realize the high doping. The results show that the dark current of the photodetector with diameter of 24 lain is about 2.5 × 10.7 μA at the bias voltage of-1 V, and the optical responsivity is 0.1 A/W at wavelength of 1.55 μm. The 3 dB bandwidth （BW） of 4 GHz is obtained for the photodetector with diameter of 24 μm at reverse bias voltage of 1 V. The long diffusion time of minority carrier in n-type Ge and the large contact resistance in metal/Ge contacts both affect the performance of Ge photodetectors.

Self-catalyzed growth of GaSb nanowires for high performance ultraviolet-visible-near infrared photodetectors

A simple self-catalyzed chemical vapor deposition process was conducted to synthesize single-crystalline GaSb nanowires,where Ga droplets were utilized as the catalysts.The as-grown GaSb nanowires exhibited typical p-type semiconductor behavior with the calculated hole mobility of about 0.042 cm^2 V^-1 s^-1.The photoresponse properties of the GaSb nanowires were studied by fabricating nanowire photodetectors on both rigid and flexible substrates.The results revealed that the photodetectors exhibited broad spectral response ranging from ultraviolet,visible,to near-infrared region.For the device on rigid substrate,the corresponding responsivity and the detectivity were calculated to be 3.86×10^3 A W-1 and 3.15×10^13 Jones for 500 nm light,and 7.22×10^2 A W-1 and 5.90×10^12 Jones for 808 nm light,respectively,which were the highest value compared with those of other reported Ga1-xInxAsySb1-y structure nanowires.Besides,the flexible photodetectors not only maintained the comparable good photoresponse properties as the rigid one,but also possessed excellent mechanical flexibility and stability.This study could facilitate the understanding on the fundamental characteristics of self-catalyzed grown GaSb nanowires and the design of functional nano-optoelectronic devices based on GaSb nanowires.

Space-confined growth of high-quality CsBi3I10 lead-free perovskite film for near-infrared photodetectors with high sensitivity and stability

As a lead-free perovskite,CsBi3I10 has attracted significant attention because of its high thermal tolerance and long electron diffusion length.Solution-processed high-performance CsBi3I10 perovskite devices,however,are hindered by the formation of a two-dimensional structure,which results in an extremely high surface roughness and many pinholes.In this paper,we reported a space-confined growth(SCG)method using a single-layer polystyrene(PS)sphere template to obtain high-smoothness,high-crystallinity,and dense CsBi3I10 perovskite films.Compared with traditionally spin-coated CsBi3I10 photodetectors(PDs),the metal-semiconductor-metal PDs made by SCG showed a higher photocurrent,a lower dark current,and a bigger on/off ratio.In addition,the photocurrent of our unencapsulated CsBi3I10 perovskite PDs was not attenuated under long-time illumination.In addition,when the device was stored in air for 30 d,its performance also showed no degradation,demonstrating ultra-high stability.Furthermore,the synthesis was free of antisolvents,such as chlorobenzene and toluene,which is beneficial for the environmentally friendly assembly of the devices.Our strategy opens up a new way to prepare high-quality lead-free perovskite,which may be useful for applications in light-emitting diodes and solar cells.

High-performance ultraviolet-visible tunable perovskite photodetector based on solar cell structure

An ultraviolet （UV）-visible tunable photodetec- tor based on ZnO nanorod arrays （NAs）/perovskite hetero- junction solar cell structures is presented, in which the ZnO NAs are prepared using the hydrothermal method and an- nealed in different atmospheres. Based on solar cell structure perovskite photodetectors, it exhibited highly repeatable and stable photoelectric response characteristics. In addition, the devices with ZnO NAs annealed in a vacuum showed a high responsivity of about 1014 cm Hz1/2 W-1 in the visible region, whereas the devices with ZnO NAs annealed in air exhib- Red good detectivity in the UV region, especially at around 350 nm. Furthermore, when the annealing atmosphere of the ZnO nanorods was changed from vacuum to air, the domi- nant detection region of the photodetectors was altered from the visible to the ultraviolet region. These results enable po- tential applications of the ZnO NAs/perovskite photodetec- tors in ultraviolet and visible regions.

High-performance flexible and broadband photodetectors based on PbS quantum dots/ZnO nanoparticles heterostructure

Flexible and broadband photodetectors have drawn extensive attention due to their potential application in foldable displays, optical communications, environmental monitoring, etc. In this work, a flexible photodetector based on the crystalline PbS quantum dots(QDs)/ZnO nanoparticles(NPs) heterostructure was proposed. The photodetector exhibits a broadband response from ultraviolet-visible(UV-Vis)to near infrared detector(NIR) range with a remarkable current on/off ratio of 7.08×10^3under 375 nm light illumination.Compared with pure ZnO NPs, the heterostructure photodetector shows the three orders of magnitude higher responsivity in Vis and NIR range, and maintains its performance in the UV range simultaneously. The photodetector demonstrates a high responsivity and detectivity of4.54 A W-1and 3.98×10^12Jones. In addition, the flexible photodetectors exhibit excellent durability and stability even after hundreds of times bending. This work paves a promising way for constructing next-generation high-performance flexible and broadband optoelectronic devices.

Fabrication and properties of ultraviolet photo-detectors based on SiC nanowires

A new type of ultraviolet photo-detectors （UVPDs） based on a bundle of highly aligned SiC nanowires was fabricated and the photo-electric properties of the UVPDs including 1-V characteristics and time response were studied in this work. SiC nan- owires were prepared by pyrolysis of a polymer precursor with ferrocene as the catalyst by a CVD route. The diameters of SiC nanowires varied from 100 to 200 nm while they were some centimeters long and the SiC nanowires were with zinc blended cubic form （β-SiC） tested by X-ray diffraction. A bundle of nanowires was fixed onto two legs＇ base by conductive silver paste to form the UVPDs. The electrical measurement of the device showed a significant increase of current when the device was exposed to 254 nm UV light, and the rising time of the device is very short, but the falling time is relatively long. Our results show that the UVPDs based on SiC nanowires have excellent electrical and optical properties which can be potentially applied.

Design and realization of high precision FBG rain gauge based on triangle cantilever beam and its performance research

A novel fiber Bragg grating （FBG） rain gauge is proposed in this paper to achieve high precision rainfall measurement. One core sensitive FBG, a temperature compensation FBG and a mechanical transition system construct this novel FBG rain gauge. Sensing principle of this FBG rain gauge is explained in detail, and its theoretical calculation model is also established, which shows that the relationship between center wavelength of sensitive FBG and external rainfall has very good linearity. To verify its detection performance, the calibration experiment on one prototype of this FBG rain gauge is carried out. After experiment data analysis, the detection precision of this FBG rain gauge is 15.4/.tm which is almost two orders of magnitude higher than that of the existing rainfall measurement device. The experimental data confirm that this FBG rain gauge can achieve rainfall measurement with high precision.

A chain-type diamine strategy towards strongly anisotropic triiodide of DMEDA·I6

Linearly bonded triiodide chains with fairly small distance between the adjacent iodine ions feature a facile electron transfer and highly anisotropic properties.Here,we demonstrate a novel strategy towards a new one-dimensional linear triiodide DMEDA·I6,using chain-type N,N'-dimethylethanediamine(DMEDA)cation to coordinate triiodine ions.This triiodide has the shortest distance between adjacent I3^- and good linearity.An estimated electronic band gap of1.36 e V indicates its semiconducting properties.100 fold differences both in polarization-sensitive absorption and effective mass were achieved by simulation,with directions parallel and perpendicular to the a-axis of DMEDA·I6.The DMEDA·I6 single crystal-based photodetectors show a good switching characteristic and a distinct polarization-sensitive photoresponse with linear dichroic photodetection ratio of about 1.9.Strongly anisotropic features and semiconducting properties of DMEDA·I6 make this triiodide system an interesting candidate for polarization related applications.

DNA template-synthesized silver nanoparticles:A new platform for high-performance fluorescent biosensing of biothiols

To develop the high-performance fluorescent bio-sensors, the metal nanoparticles were employed as nanoquenchers and at- tracted reasonable attention in the design of fluorescent biosensors. In this work, silver nanoparticles （AgNPs） were obtained via reduction of Ag＋ on FAM-labeled DNA template. For the tight binding between AgNPs and DNA, the tem- plate-synthesized AgNPs turned out high quenching efficiency and could be applied as super nanoquenchers to establish the biosensing platform for fluorescent detection. As an example, the template-synthesized DNA-AgNPs conjugates were em- ployed in sensing thiols. By forming S-Ag bonds, thiols interact intensely with AgNPs and replace the FAM-labeled DNA off from the surface of AgNPs, resulting in a fluorescence enhancement. Besides the advantages of lower background and higher signal-to-background ratio （S/B）, the conjugates present better stability, making them applicable in complicated biological fluids. To further evidence the feasibility of sensing thiols in real samples, the thiols in human urine were detected. The total amount of free thiols found in human urine was ranging from 229 μM to 302μM with the proposed sensor. To conclude the reliability, low content of Cys was added and the recovery was 98%-103%.