斜入射干涉检测大口径碳化硅平面反射镜

采用自行研制的口径为600 mm的近红外相移平面干涉仪在斜入射条件下对大口径碳化硅(SiC)平面反射镜进行了绝对测量.首先,在一个标准的斐索干涉测试结构中测出空腔波面数据;然后,将被测平面置于干涉光路中,使被测件光轴与干涉仪光轴成α角,测得第二组波面数据.对两组波面数据处理后得到SiC平面反射镜中心垂线方向的绝对面形分...     

中频波面的旋转平移法干涉绝对检验

基于Zernike多项式拟合的传统干涉绝对检验方法由于平滑了波面和丢失了中频成分,仅可以实现面形误差的绝对检验.本文提出利用旋转平移法来实现中频波面的干涉绝对检验.将被测波面分解成旋转对称成分和旋转非对称成分,通过N次旋转被测件,求解波面中的旋转非对称成分;通过平移被测件实现伪剪切,求解波面中的旋转对称成分.与传统绝对检验方法相比,该方法既能够恢复整个波面,又不需要对整个波面进行Zernike多项式拟合;由于仅对旋转对称成分用偶次多项式进行提取,提升了计算速度,降低了拟合误差,保留了中频成分,数值仿真显示其比传统方法优越,测量精度可达到1 nm rms.在ZYGO干涉仪上完成了平面元件的干涉绝对检验测量.采用改变伪剪切比和更换标准镜两种方案,分别实现了实验数据的自比对;将测试结果与经典三面互检法得到的水平和垂直方向的一维轮廓数据进行比对,验证了旋转平移法的准确性.     

球面绝对检测及误差控制

高精度检测技术是促进光学加工技术发展的必备条件.ZYGO干涉仪检测光学表面面形代表着国际先进水平,常规检测精度取决于仪器配备的标准镜头(通常标准镜头精度为λ/10,最高精度可达λ/20),λ/20测量精度不能满足更高精度面形检测的需求.本文探讨了表面绝对检测技术及误差控制,通过用ZYGO干涉仪及两种精度等级的参考镜头对f/1.07的球面镜进行常规GPI干涉和双球面实时绝对检测比对,证明了表面绝对检测的有效性.实验及分析表明在超净实验室、高精度防振平台、高精密可旋转5维调整架及精密导轨的测量条件下,采用表面绝对测量技术,严格控制基准定位和共焦位置旋转角度定位,多次重复测量,λ/10标准镜头同样能够达到λ/30 PV的高精度检测目的.     

斜入射法测量蓝宝石基片仿真分析与实验

为获取具有微米量级变化的蓝宝石基片的面形分布,采用斜入射法拓展数字干涉仪测量范围。根据斜入射测量原理,推导了斜入射角、平面面形偏差与系统波像差之间的关系。通过Zemax构建了斜入射测量仿真光路,研究了面形偏差及入射角度对检测结果的影响。通过仿真实验得出最佳斜入射角度等关键参数,并在斐索干涉仪上测量了直径为100 mm的蓝宝石基片,测量结果的PV为5.182μm,RMS为1.251μm。研究了斜入射角对分辨率、灵敏度因子、条纹对比度的影响。研究表明,斜入射角为70°时,适宜测量矢高值≤5μm的蓝宝石基片,引入误差小于0.1μm,测量范围是正入射测量范围的1.46倍,且能获得适宜的条纹对比度。     

非球面补偿板三维面形检测方法的研究

本文对准直激光束检测非球面方法进行了研究。它不用接触被检件表面,同时也无须处理干涉条纹。测量时只要保证激光细束保持一致的入射方向扫描被检表面,用CCD光电探测器检出面形的斜率变化,而后在扫描范围内积分便能获得面形高度。本文以测量光学系统中用于波面补偿目的的旋转对称镜面为例对测量系统进行分析。该系统不仅可以进行一维测量,通过转台旋转亦可进行二维测量,通过面形重构获得三维的被测体面形。给出了三维面形重构方法,并编制数据处理软件,可以把测量数据处理成高度曲线或三维面形。     

非球面补偿板三维面形检测方法的研究

本文对准直激光束检测非球面方法进行了研究。它不用接触被检件表面,同时也无须处理干涉条纹。测量时只要保证激光细束保持一致的入射方向扫描被检表面,用CCD光电探测器检出面形的斜率变化,而后在扫描范围内积分便能获得面形高度。本文以测量光学系统中用于波面补偿目的的旋转对称镜面为例对测量系统进行分析。该系统不仅可以进行一维测量,通过转台旋转亦可进行二维测量,通过面形重构获得三维的被测体面形。给出了三维面形重构方法,并编制数据处理软件,可以把测量数据处理成高度曲线或三维面形。     

用于光学表面检测的数字波面干涉仪

本文讨论了最近研制成功的用于光学表面检测的数字波面干涉仪。利用实时位相检测技术可以高精度重构出数字波面,叙述了仪器的光学系统,电子学接口和软件。该仪器可测定光学平面和球面的面形,精度分别达到λ/40和λ/20,由终端输出面形的数据。     

基于ASTM方法的光学平面面形检测

为分析光学平面面形偏差,以直径100mm光学平晶为检测对象,利用斐索干涉仪采集了被测光学平面的波面干涉图,按照美国材料与试验协会(American Society for Testing and Materials,ASTM)标准方法,通过分析,能够定性反映出被测光学平面的面形偏差。计算并分析了波面偏差指标峰谷值PV和均方根值RMS,将计算结果与利用ZYGO斐索干涉仪测得的数据对比,偏差为10-3λ,符合光学检测要求。综合考虑可操作性和计算精度,这种基于ASTM的方法是一种行之有效的光学检测分析方法。     

LDI-2激光数字波面干涉仪

<正> 富通光电工程公司新近开发出 LDI—2激光数字波面干涉仪。仪器采用独特的数字移相方法,可进行实时数字干涉测量。这种干涉仪可用于精确定量测量凹球面镜的面形误差和曲率半径。配备辅助光学件后,本仪器还可以测量凸球面、平面、非球面镜的面形误差以及光学系统的波像差等。仪器最大可测孔径达 F1.3,仪器不确定度λ/50(F4)、λ/5(F1.3)。     

Shack-Hartmann波前传感器检测大口径圆对称非球面反射镜

针对大口径非球面反射镜在研磨阶段后期其面形与理想面形存在较大偏差,且表面粗糙度较大、反射率较低,采用轮廓仪和普通干涉仪检测无法满足测试要求等问题,提出采用动态范围大且精度高的Shack-Hartmann波前传感器来检测大口径非球面反射镜.研究分析了Shack-Hartmann波前传感器检测系统的原理及系统误差并编写了相应的数据处理软件.为了验证该方法的可行性,对已经加工完成的350 mm口径旋转对称双曲面面形进行了检测,测量得到的面形误差PV值、RMS值分别为0.388λ、0.043λ(λ=632.8 nm);与干涉测量的标准结果进行了对比,得到的面形偏差PV值、RMS值分别为0.014λ和0.001λ.对比结果表明,Shack-Hartmann波前传感器的测量结果正确可靠,从而验证了Shack-Hartmann波前传感器检测大口径非球面反射镜的可行性.     

Optimization of the chemical mechanical polishing process for optical silicon substrates

Chemical mechanical polishing (CMP) experiments are performed to study the effects of four key process factors on the flatness and surface finish of the polished optical silicon substrates and on the material removal rate (MRR). The experimental results and analyses reveal that the pad rotational speed and polish pressure have significant effects on the MRR, the interaction of the polish head rotational speed and slurry supply velocity and the interaction of the polish pressure and polish head rotational speed have significant effects on the flatness, and the pad rotational speed has a significant effect on the surface roughness R _t of the optical silicon substrates polished. The optimal combination of the four factors investigated is a polish pressure of 9,800 Pa, a pad rotational speed of 20 rpm, a polish head rotational speed of 20 rpm, and a slurry supply velocity of 100 ml/min. A confirmation CMP experiment has been carried out using the optimal process parameter setting obtained from the design of experiments analyses. The goal to attain optical silicon substrates with nanometric surface roughness and micrometric flatness by an optimized CMP process with a high MRR simultaneously so as to reduce the polishing time to only 15 min from over 8 h has been achieved.     

HC轧机平直度调节手段对各次平直度分量的影响规律研究

现代轧机一般配备多种平直度调节手段,各种调节手段之间存在着一定的耦合关系,为分析各种平直度调节手段对各次平直度分量的影响规律,采用分割模型影响函数法和条元变分法建立HC轧机的平直度计算模型,利用该模型计算倾辊、工作辊弯辊、工作辊非对称弯辊和中间辊横移4种调节手段对1次、2次、3次和4次平直度分量的影响系数,分析发现,倾辊和工作辊非对称弯辊对平直度的影响规律类似,主要影响1次和3次平直度分量,并且对1次分量的影响程度要大于对3次分量的影响程度;工作辊弯辊和中间辊横移主要影响2次和4次平直度分量,并且对2次分量的影响程度要大于对4次分量的影响程度,该结果系统地揭示各种调节手段对各次平直度分量的影响规律,为平直度在线控制模型的建立、实现提供理论基础。     

硬质合金工件精磨表面粗糙度及平面度的试验研究

通过对硬质合金工件的磨削试验,分析了不同砂轮对工件表面粗糙度的影响,优选出可获得最佳表面质量的砂轮。通过将Matlab应用于磨削表面平面度检测的数学建模,提高了工件平面度的检测精度。     

低频水下声信号调制下衍射光场的分布

建立了一个简单可行的光学系统用于探测低频水下声信号。水下声信号产生的低频声波通过水介质传到液体表面产生表面波,激光束入射到液面时,在光屏上观察到了清晰、稳定的衍射图样,发现在低频水下声信号的调制下衍射光场的分布具有明显的不对称性。实验中得到了衍射图样光斑光强与位置的分布,理论分析发现,结果与实验所观察到的现象是很吻合的。结果表明,在低频水下声信号调制下衍射光场的分布是非对称分布的。     

Ignition and combustion characteristics of the gas turbine slinger combustor

This paper describes the ignition and combustion characteristics of a gas turbine slinger combustor with rotating fuel injection system. An ignition test was performed under various airflow, temperature and pressure conditions with fuel nozzle rotational speed. From the test, there are two major factors influencing the ignition limits: the rotational speed of the fuel nozzle, and the mass flow parameter. Better ignition capability could be attained through increasing the rotational speed and air mass flow. From the spray visualization and drop size measurement, it was verified that there is a strong correlation between ignition performance and drop size distribution. Also, we performed a combustion test to determine the effects of rotational speed by measuring gas temperature and emission. The combustion efficiency was smoothly enhanced from 99% to 99.6% with increasing rotational speed. The measured pattern factor was 15% and profile factor was 3%.     

Viscoelastic behavior of polishing pad: Effects on edge roll-off during silicon wafer polishing

In semiconductor device fabrication, surface flatness of silicon wafers has a significant impact on the chip yield. Hence, there is a strong demand to prevent the deterioration in surface flatness near the wafer edge due to edge roll-off during polishing. In the present study, we investigate the viscoelastic behavior of polishing pads and its effects on the uniformity of material removal distribution near the wafer edge. On the basis of the findings, we propose polishing conditions required to improve surface flatness near the wafer edge. The double-sided polishing experiments performed using silicon wafers reveal that the proposed polishing conditions effectively reduce edge roll-off.     

变桨轴承钢球/沟道接触载荷分布规律

工程实践表明,安装基础刚性、螺栓预紧力、安装表面平面度等各种因素对风力发电机变桨轴承的运行性能有显著影响,钢球/沟道接触载荷分布规律是研究转盘轴承运行性能、承载能力及寿命等的基础。讨论了一种用弹簧单元模拟钢球/沟道接触的有限元建模方法,并给出了应用实例,研究了安装基础刚性、螺栓预紧力、安装表面平面度等对变桨轴承钢球/沟道载荷分布规律的影响。     

轴流泵变转速性能试验及内部流场数值计算

研制比转速550 r/min、转速2 900 r/min型QY90-4.4-1.5潜水轴流泵样机。通过型式及变转速外特性试验,得出轴流泵qV-H、qV-Pa和qV-η性能曲线变化规律;验证qV-H、qV-Pa曲线及各转速最优工况之间换算均不满足相似定律,泵综合特性曲线等效曲线与相似抛物线差别较大;采用计算流体力学(Computational fluid dynamics,CFD)方法进行转速对流场影响数值计算,得到不同转速下最优工况叶片表面速度和静压分布,阐明外特性变化规律内在原因;泵转速提高,叶片表面速度增大,内部流动基本符合圆柱层流面无关性假设;同时叶片所受升力增大,叶片背面所承受的负压强进一步降低,易发汽蚀的可能性增大,可以推测汽蚀是制约轴流泵高速化发展的主要因素之一。轴流泵内部液流轴向运动雷诺数较小,难以达到尼古拉兹试验粘性力相似的自动模型化区,且叶栅与单翼型升力系数的差异,也难以保持变转速工况之间升力的相似,这是不满足相似定律的主要原因。     

Effect of impact angle on the slurry erosion–corrosion of 304L stainless steel

This communication describes an investigation of the effect of impact angle on slurry erosion–corrosion of stainless steel using a new slurry erosion rig. With the new apparatus, it is possible to measure the individual erosion events under impact as both electrochemical current/time transients, and mechanical transients through acoustic emission (AE) simultaneously. Each sharp rise observed in the electrochemical current transient under particle impact is accompanied by an AE event. These sharp current rises are attributed to the rupture or removal of the oxide film on the surface by the abrasive particles. The correlation between the current rise and the maximum of the AE event, although scattered, shows an increase with decreasing impact angle. The current transients due to individual erosion events show that on the average, the current rise is greater and the rise time is longer at oblique angles compared with those at normal incidence. The degree of denudation of the metal surface by individual particle impingements, the process which strips the surface of its passivity, increases at more oblique angles. Weight loss measurements demonstrate that the synergistic effect between erosion and corrosion is enhanced by a more oblique angle of impact. The origin of the synergism is discussed.