【作者】 宋殿友；

【导师】 刘铁根；

【作者基本信息】 天津大学 ， 光电子技术， 2012， 博士

【摘要】 PSD(位置敏感器件)作为一种光斑位置检测器件，相比CCD和CMOS器件，具有多种不可比拟的优势，因此，在各种测量领域其都将有很好的应用前景。本文首先对PSD特性和激光三角法进行了理论分析，并结合幅度调制解调原理制定了微位移测量方案；其次，通过对光源、光斑质量、被测表面特征和散斑等各种光学特性对测量影响的研究，确定了测量系统光学部分的重要参数；然后，在分析了干扰信号、不对称性和非线性等各种因素对PSD信号处理影响的基础上，设计了一款基于调制解调技术的PSD信号单通道处理模块，并结合光学部分集成制作了微位移测量系统样机，同时进行了系统性能实验验证和分析。最后，将差动激光三角法和微位移测量系统应用于精密薄板测厚系统，并设计了实验样机和工业样机，取得了良好效果。本文的创新性工作主要包括以下五部分：1、提出了将狭缝（小孔）空间滤波技术和双光束补偿原理相结合的光斑整形方法。该方法提高了激光光斑质量，大大降低了由于光斑的高频噪声和光斑整体偏移造成光斑重心漂移而产生的测量误差。2、提出了基于PWM&PFM(脉冲宽度调制和脉冲频率调制)激光调制的自适应被测表面特征的方法，该方法使系统能够自适应由于各种被测对象表面状况的不同引起的像斑强度变化，解决了以往采用数控电位器调节信号强度或通过改变激光器电流调节激光强度方法所带来的不易集成和测量误差增大等问题。3、提出了基于信号调制、带通滤波和峰值检测技术的PSD信号单通道处理方法，该方法在没有滤光片的情况下，有效地消除了背景光、暗电流的影响，同时降低了成本并大大抑制了温漂的影响。4、结合PSD输出特性，针对峰值检测的非线性和PSD本身的非均匀性畸变，提出了双重非线性校正的方法，并将分段最小二乘法应用于双重非线性校正，该方法既保证了系统的测量精度，同时也使系统易于处理，适合采用嵌入式技术实现。5、提出了将基于变频调制、高阶带通滤波、峰值检测等技术的PSD信号单通道处理方法和激光三角法相结合的微位移测量方法，通过该方法设计并制作了测量频率可达2KHz,分辨率达0.35‰，线性度好于12‰，电路温漂系数极小的具有自适应能力的激光微位移测量系统。更多还原

【Abstract】 As a kind of device for detecting the position of incident light, PSD (positionsensitive device) have many advantages compared CCD and CMOS. Therefore PSDwill have a good prospect of application in many kinds of fields on measurement.Firstly, the PSD characteristics and laser triangulation method are analyzedsystematically in this dissertation, and a micro-displacement measurement programsis developed combined the amplitude modulation and demodulation principle.Secondly, through the study of the impacts of light source, beam quality, measuredsurface characteristics and speckle on the measurement, we determine the importantparameters of the optical system. Then, based on the analysis of influence ofinterference signal, asymmetric and nonlinear on the PSD signal processing, amodem-based and PSD signal single-channel processing module is designed. Incombination with optical part, we make a micro-displacement measuring systemprototype, and give an experimental validation and analysis of system performance.Finally, we have designed the experimental prototype and industrial prototype ofprecision sheet thickness measurement system by using PSD micro-displacementsensors and differential triangulation，and achieved good results.The major innovations of the dissertation mainly include five parts, as follows:1. A spot shaping method based on the slit or pinhole spatial filtering technologyand dual-beam compensation principle is proposed. The method improves the qualityof laser spot, and greatly reduces the measurement error caused by drift of the centerof spot intensity which is mainly caused by high-frequency noise and spotdisplacement.2. An adaptive method based on PWM&PFM(pulse-width modulation andpulse-frequency modulation) laser modulation was applied to the measurementsystem。This method allows the system to be adaptive as the spot intensity variationcaused by different measured surface, and solves the problems, such as integrationdifficutlty and measurement error increases, which are brought about by theconventional methods such as using digitally controlled potentiometer to adjusting thesignal strength and changing the laser current to adjust the intensity of the laser.3. A PSD signal single-channel processing method based on many signalprocessing techniques including modulation, band-pass filter, peak detection, etc, isproposed. In case of no filter the method eliminates the impact of background lightand dark current, reduces the cost and significantly suppresses the temperature drift. 4. Combined with the PSD output characteristics, a dual nonlinear correctionmethod is proposed to correct the non-linearity of PSD and peak detection, and thealgorithm including segmentation processing and least squares method is applied tothe method. The method not only guarantees the measurement accuracy of the system,but also make the system easy to handle, and is suitable for embedded technology.5. A micro-displacement measurement method based the combination of PSDsignal single-channel processing and the laser triangulation is proposed, and the signalprocessing techniques include modulation, band-pass filter, peak detection, etc. Alaser micro-displacement measuring system is made according the method, withmeasurement frequency up to2KHz, resolution up to0.35‰, stability error betterthan0.90‰, linearity better than12‰.更多还原