三维测量工业内窥镜的双目光学系统

针对国内工业内窥镜只限于观察,无法满足工件三维尺寸测量的现状,设计了一种探头外径为6mm并且可以向任意方向弯曲的三维测量工业内窥镜,并介绍了该内窥镜的双目光学系统及镜体内部结构的设计。首先,基于双目立体成像的原理,提出了一种具有双物镜、单图像传感器的新型双目光学系统。其次,根据光学系统的技术要求,设计了内窥镜的头部结构。考虑到一些工件内部结构比较复杂,分别设计了内窥镜的可弯曲结构以及后部操控机构以方便一些精密工件的检测。最后,通过三维图像处理软件对待测物表面两个特征点进行长度测量试验,得到了两个特征点的间距。实验结果表明:待测物表面两个特征点的长度测量误差在±0.2mm内。该系统基本实现了工业内窥镜的三维测量功能。

一种利用透射式太赫兹时域光谱技术精确提取样品折射率的方法

运用透射式太赫兹时域光谱技术提取可区分回波样品折射率,主要依靠测得信号的相位差计算得到.具体有两种方法:一是利用参考脉冲和太赫兹波第一次透过样品的脉冲信号,二是利用太赫兹波第一次透过样品的脉冲信号和经样品内部反射两次后的第二个透射信号.实际操作中入射光束与样品表面法线存在夹角,该夹角不易测量,计算时通常忽略,这会最终引起折射率的测量误差,且该误差与选用的折射率提取方法有关.在分析两种方法因夹角引起误差的基础上,提出一种全新的折射率修正方法,该方法能从理论上消除夹角引起的误差,同时实验验证了该方法的有效性.

CsB3O5晶体高效三倍频产生28.3W 355nm激光

利用CsB_3O_5(CBO)晶体对Nd:YAG声光调Q准连续1064 nm激光的高效三倍频效应获得高功率355 nm激光输出.1064 nm激光采用大功率脉冲式半导体激光(LD)列阵侧面抽运Nd:YAG晶体的主振荡-功率放大(MOPA)系统实现210 W的调Q准连续输出,激光以1 kHz脉冲串方试运转,每个脉冲串包含5个调Q脉冲,单脉冲宽度为40 ns.经I类LiB_3O_5(LBO)晶体倍频产生98 W 532 nm绿光.通过30 mm长的II类CBO晶体对1064 nm与532 nm光和频获得28.3 W的355 nm紫外光,相应的三倍频转换效率为13.5%,比相同条件下II类LBO晶体高28.6%.研究了CBO三倍频产生355 nm光的温度敏感特性,得到其温度带宽为25?C,远大于LBO晶体的4?C.实验证明,CBO晶体在三倍频产生355 nm的转换效率和温度不敏感性方面均优于LBO晶体.

高功率窄线宽可调谐1064nm环形腔激光

文章采用了三镜环形腔内插入标准具获取高功率窄线宽可调谐1 064 nm激光。对环形腔的单向运行、标准具压窄线宽与调谐波长及激光大基模体积运转进行了理论分析与计算,结合实验优化了腔镜曲率与输出耦合率。在808 nm半导体激光泵浦功率151 W条件下,获得输出功率33.7 W、光束质量因子M 2=1.28、线宽0.1 GHz的单向1 064 nm激光输出,相应的光转换效率22.3%。采用高精度控温仪对标准具进行精确温控,实现激光波长的精密调谐。改变标准具温度获得1 064 nm波长调谐范围72.6 GHz,调谐精度为220 MHz。波长调谐过程中1 064 nm激光输出功率变化约10%。整个系统稳定可靠,而且相对简单,较易实现,为获得可调谐窄线宽1 064 nm激光提供了实用有效的技术手段。

多波长皮肤光疗仪的设计

为提高光生物效应治疗皮肤病的效率,解决光疗仪器辐照度普遍偏低的问题,基于光生物调节与光动力作用的原理及其临床应用,设计了一种具有治疗痤疮等功能的多波长皮肤光疗仪。用TracePro进行光学系统的设计与仿真,通过对LED光源进行硬件电路设计,使光能量布局集中且均匀,提高光的辐照度,且不同光波长和光能可自由组合使用。测试结果表明,该光疗仪在目标平面光照集中且均匀,总辐照度达50.5 mW/cm^2以上。

砷化镓吸收式光纤温度传感技术的解调方法

针对目前砷化镓吸收式光纤温度传感技术的数据解调方法叙述不详解且解调精度不高,本文以砷化镓光纤温度传感器的吸收光谱随温度变化的关系为基础,研究了一种基于光谱分析的砷化镓吸收式光纤温度传感技术的温度解调方法,提出一种新的数据处理流程。本文采用标准温度测量系统验证了该解调方法和数据处理流程。结果表明,在25℃~70℃区间内,测量精度小于±0.1℃;在70℃~250℃区间,测量精度小于±0.7℃。

太赫兹单像素计算成像原理及其应用(特邀)

太赫兹成像技术具有透视性、安全性以及光谱分辨能力等独特优点,有着广泛的应用前景。由于太赫兹面阵探测器的技术成熟度低、价格昂贵,太赫兹成像技术在较长时间内以单点扫描方案为主,存在系统复杂、成像耗时长等问题。近年来,基于计算成像算法的太赫兹单像素成像技术发展迅速,成为了获取太赫兹图像的重要途径之一。文章综述了太赫兹单像素计算成像技术的基本原理、技术实现手段和应用前景,总结了现存的一些关键问题,并展望了一些今后可能的发展方向。

空间欠采样太赫兹时域光谱成像方法

文章针对传统太赫兹时域光谱成像技术存在的扫描时间长以及数据存储量大等问题,提出了一种基于压缩感知理论的空间欠采样太赫兹时域光谱成像方法。首先通过扫描电机获得目标非等间隔欠采样信号,然后利用压缩感知方法来重构缺失像素点的太赫兹信息。实验结果显示,当压缩比为0.5时,所重构的太赫兹信号与全采样条件下的信号相关性可达99.95%。通过对压缩重建图像的显示分析,时域图像中的缓变区域和频谱成像中的低频信号恢复效果较好。该方法为快速太赫兹光谱成像提供了一种有效的技术手段。

基于聚焦物镜与PSD的激光对中测量方法研究

针对传统激光对中方法数学模型复杂、求解困难的不足,提出一种基于聚焦物镜与PSD的激光对中测量方法。该方法利用光学系统中视场与焦距的关系以及相似三角形的原理得到不对中的角度偏差和平行偏差,测量原理简单,求解方便。实验结果表明,当平行偏量和角度偏量的测量范围分别为0.5mm^1.5mm,0.047 7°~0.143 2°时,平行偏量测量误差范围为0.035mm^0.207mm,角度测量误差范围为0.000 2°~0.012 8°。最后对系统测量误差进行分析并提出一种消除安装误差影响的方法,给出了计算公式。

基于光学参量效应的太赫兹辐射源及其研究进展

太赫兹频段是电磁波谱中极具科学价值但尚待完全开发的电磁辐射区域,其中,太赫兹辐射源是影响太赫兹频段能否被广泛应用的关键器件,也是太赫兹技术研究领域的前沿问题。基于光参量效应产生太赫兹波的方法具有非线性转换效率高、波长在一定范围内连续可调、易小型化、能够在室温下稳定运转等优点,近年来得到了广泛的关注。文章介绍了光参量效应产生太赫兹波的原理,分析了影响太赫兹波输出功率的因素,总结介绍了其在国内外的代表性研究进展,最后提出了一定的改进方法。

放电等离子体烧结法制备的Nd:Lu_2O_3陶瓷的高效激光运转

文章主要针对基于放电等离子体烧结方法制备的透明Nd:Lu_2O_3陶瓷激光性能展开实验研究。研究结果显示,退火后的Nd:Lu_2O_3陶瓷样品激光性能远优于退火前的样品:当采用直线腔测试方法时,退火后样品获得了最高功率为880 mW,最大斜效率为40%的输出;当采用V型腔测试方法时,退火后样品获得了最高为1.25 W,最大斜效率为38%的输出,输出光谱包含了两条位于1 076.7 nm和1 080.8 nm的谱线,但功率的进一步提高受到严重的热透镜效应限制。实验结果表明,通过放电等离子体烧结方法可以制备出高光学质量的Nd:Lu_2O_3陶瓷样品。

A 4.8-W M^2 = 4.6 Continuous-Wave Intracavity Sum-Frequency Diode-Pumped Solid-State Yellow Laser

A yellow continuous wave with beam quality M^2= 4.6 and output power of 4.8 W at 589nm is generated by intracavity sum-frequency mixing of 1064 nm and 1319 nm radiations of a Nd：YAG laser. To achieve high beam quality at high power, thermally near-unstable flat-flat resonators with two-rod birefringence compensation are designed to obtain the large fundamental mode size inside the Nd：YAG rods and the same beam width inside the KTP crystal. The optimal intracavity power ratio of both 1064nm and 1319nm beams is also considered. The output power fluctuation of the yellow laser remains less than 5% in four hours.

A Continuous-Wave Diode-Side-Pumped Tm：YAG Laser with Output 51W

A compact diode-side-pumped Tm：YAG laser is presented, which can output 51 W of cw power at 2.02 μm. The Tm：YAG rod is side pumped by nine diode arrays with the central wavelength of 783nm and the with bandwidth of about 2.5 nm at 25^o C. To decrease the thermal effect on the both ends and dissipate the heat effectively, one composite Tm：YAG rod with the undoped YAG end caps and the screw threads on the side surface of the rod is used as the laser crystal. The maximum optical-to-optical conversion efficiency of the 2.02-μm laser output is 14.2%, with a slope effciency of 26.8%

High Efficiency Multi-kW Diode-Side-Pumped Nd：YAG Laser with Reduced Thermal Effect

We demonstrate a high efficiency multi-kW diode-side-pumped Nd：YAG laser. High cooling efficiency of the diode-side-pumped module in the laser is achieved. The middle portion of the Nd：YAG rod in the module is cooled by a coolant jet with screwed side surface, and the end-caps of the rod without screwed side surface are cooled by Au coated on the surface. The thermal effect of the laser rod is reduced, which leads to high output power with high optical-optical conversion efficiency. By using three identical Nd：YAG laser modules, an output power of 4.2 kW and beam quality of 58 mm＆#12539;mrad with an optical-optical efficiency of 35% at 1064 nm is obtained in a laser oscillator. By using four identical Nd：YAG laser modules, an output power of 3.1 kW and beam quality of 17 mm＆#12539;mrad with an optical-optical efficiency of 25.8% is demonstrated in a master oscillator power-amplifier system.

High power high beam quality diode-pumped 1319-nm Nd:YAG oscillator-amplifier laser system

This paper demonstrated a high power and high beam quality diode-pumped 1319-nm Nd：YAG master oscillator-power amplifier laser system. A thermally near-unstable resonator with four-rod birefringence compensation fiat-fiat cavity was adopted as the master oscillator. A solid etalon was inserted in the unidirectional ring resonator to compress the laser linewidth. Under a repetition rate of 500 Hz and pulse width of 160 μs, the master oscillator delivers an average output power of 16.8 W at 1319 nm with linear polarisation, beam quality factor M^2=1.16 and linewidth of 3.2 GHz. A double-pass power amplifier with two amplifier stages was employed for higher power scaling and the output power was amplified to be 25.9 W with M^2 = 1.43.

Passively Q-Switched Nd：KLuW Laser with Semiconductor Saturable Absorber

We demonstrate a passively Q-switched Nd：KLu W laser with a semiconductor sat urable absorber mirror （SESAM） at wavelength 1070 nm. At a pump power of 1.3 W, the pulse width is measured to be about 17ns with repetition rate of lOkHz and with the average output power of 260roW. To our knowledge, this is the first demonstration of Nd：KLuW used for passively Q-switched laser with an SESAM.

Unidirectional plasmonic Bragg reflector based on longitudinally asymmetric nanostructures

Plasmonic Bragg reflectors are essential components in plasmonic circuits.Here we propose a novel type of plasmonic Bragg reflector, which has very high reflectance for the right-side incidence and meanwhile has extremely large absorption for the left-side incidence.This device is composed of longitudinally asymmetric nanostructures in a metal–insulator–metal waveguide.In order to efficiently analyze, design, and optimize the reflection and transmission characteristics of the proposed device, we develop a semi-analytic coupled-mode model.Results show that the reflectance extinction ratio between plasmonic modes incident from the right-side and the left-side reaches 11 dB.We expect this device with such striking unidirectional reflection performance can be used as insulators in nanoplasmonic circuits.

Highly Efficient Diode-Side-Pumped Six-Rod Nd：YAG Laser

We have demonstrated a highly efficient, high average output power laser based on the optimized resonator made up of multiple Nd： YA G rods. The laser consists of three groups, each of which contains two rods with one quartz 90° rotator between them. By a desirable design of the resonator, the average output power of 1906 W at 1064 nm is reached with repetition rate of 1.1 kHz. The optical to optical conversion efficiency is up to 50.8% with the pulse width 224 μs and it is the highest conversion efficiency of six rods resonator.

Spectroscopic measurements and terahertz imaging of the cornea using a rapid scanning terahertz time domain spectrometer

Spectroscopic measurements and terahertz imaging of the cornea are carried out by using a rapid scanning terahertz time domain spectroscopy（THz-TDS） system.A voice coil motor stage based optical delay line（VCM-ODL） is developed to provide a rather simple and robust structure with both the high scanning speed and the large delay length.The developed system is used for THz spectroscopic measurements and imaging of the corneal tissue with different amounts of water content,and the measurement results show the consistence with the reported results,in which the measurement time using VCM-ODL is a factor of 360 shorter than the traditional motorized optical delay line（MDL）.With reducing the water content a monotonic decrease of the complex permittivity of the cornea is observed.The two-term Debye relaxation model is employed to explain our experimental results,revealing that the fast relaxation time of a dehydrated cornea is much larger than that of a hydrated cornea and its dielectric behavior can be affected by the presence of the biological macromolecules.These results demonstrate that our THz spectrometer may be a promising candidate for tissue hydration sensing and practical application of THz technology.

A 1550-nm linearly tunable continuous wave single-mode external cavity diode laser based on a single-cavity all-dielectric thin-film Fabry Pérot filter

A 1550-nm linearly tunable continuous wave （CW） single-mode external cavity diode laser （ECDL） based on a singlecavity all-dielectric thin-film Fabry-Pérot filter （s-AFPF） is proposed and realized in this paper. Its internal optical components as well as their operation mechanisms are introduced first, and then its longitudinal mode output characteristic is theoretically analyzed. Afterwards, we set up the experimental platform for the output characteristic measurement of this tunable ECDL; under different experimental conditions, we execute accurate and real-time measurements for the output central wavelength, output optical power, output longitudinal mode distribution, and the line-width of the tunable ECDL in its tuning process. By summing up the optimal experimental condition from the measured data, we obtain the optimal tunable ECDL relevant parameters： the tunable ECDL has a linear mode-hop-free wavelength tuning region of 1547.203 nm-1552.426 nm, a stable output optical power in the range of 40 μW-50 μW, and a stable output longitudinal mode distribution of a single longitudinal mode with a line-width in the range of 100 MHz-150 MHz. This tunable ECDL can be used in environmental gas monitoring, atomic and molecular laser spectroscopy research, precise measurements, and so on.