A nondestructive laser profiler based on optical scanning method using a commercial compact laser triangulation displacement probe is described to measure the profile of the pipe inner wall surface. According to the optical feature of measured pipe inner wall surface, the adjusting posture method of laser triangulation displacement probe is put forward to reduce the disturbance and increase the measuring accuracy. the experiments are given. The method of the wavelet transform to analyze the measure results is used. The resolution of the nondestructive laser profiler is 30 micrometers .
A non-contact laser sensor based on the circular optical cutting image is developed to measure the size and the profile of the pipe inner wall. The sensor consists of a laser diode light source, an optical ring pattern generator and a CCD camera. The circular light from the optical ring pattern generator projects onto the pipe inner wall, which is then viewed by the CCD camera. The adapt weighted average value filter and subpixel technique in several step computing and half Gauss fitting are put forward to obtain the edge and the center of the circular image in order to filter the noise of the image and raise the resolution of the measuring system. The experimental results show that the principle is correct and the techniques are realizable.
KEYWORDS: Sensors, 3D metrology, System integration, Laser systems engineering, Semiconductor lasers, Light sources, 3D modeling, Databases, Computer simulations
In this paper an integrated scanning laser sensor system with large working distance for 3-D free form measurements is described. The sensor system consists of one diode laser light source and four position sensitive device (PSD) detectors. By the Lambertin model for diffusing surface, the fundamental analysis is performed. The working distance is 150 mm - 200 mm and measuring range is 80 mm. Therefore, the scanning measurement can be realized almost without Z axial tracing. Meanwhile the surface normal direction that is the inclination angles along the X axial and Y axial can be calculated at the same time. According to the inclination data, the measurement error can be compensated by verification database. Computer simulation and preliminary experimental results are also given in this paper.
In this paper a laser triangulation scanning method for the non-contact measurement of scratches on aircraft skins and window surfaces is described. According to analyses of diffusing and reflecting properties of the measured surface, the correct setting of the laser triangulation probe is given. The adjusting posture of probe method and the spreading surface method have been developed to improve the measurement accuracy. The scratch depth measuring system (SDMS) is made. It is characterized by working distance 38 mm, measurage range 5 mm, simple structure as well as low cost. The experimental results are given.
A new principle formula of optical triangulation displacement measurement has been built by the use of the theory of light scattering from object surface. The new formula has been compared with the existing formula based on the geometric optics. The main factors affecting the precision of displacement measurement has been analyzed with the new formula. The preliminary experiment results about the new formula have been reported. Some methods which can be used to reduce and correct the measurement error have been advanced.
This paper describes a non-contact laser sensor for pipe inner wall inspection using the circular optical cutting method. The sensor which consists of laser diode light source, an optical ring pattern generator and a CCD camera principally. The optical ring pattern generator forms the light from the laser diode as a circular light to project on the pipe inner wall. Then the reflected or the scattered light by the pipe inner circumference surface is imaged on the CCD camera. The fundamental performance analysis and simulation according to the theory of the light reflecting- scattering shows that it is possible to select the propose parameters. Using this sensor mounted on an automated moving systems on trial, the pipe interior diameter between 80mm to 160mm can be inspected within accuracy of 0.2mm.
In this paper a laser diode multisensor system for 3D free form surface non-contact measurement is described. The basic measuring principle is the optical triangulation method. The influence caused by the measured surface inclination is discussed first. Two prototypes of this system have been developed. One is the laser star multisensor system and the other is the linear polarized laser sensor with four PSDs. There are suitable to measure the machined 3D free form surface as well as the 3D free form surface made of `soft' materials such as clay and wood. The detected displacement is +/- 2 mm and the surface inclination could be up to +/- 90 degrees without a rotation servomechanism to track the surface normal. The computer simulation and experimental results are given.
We describe a new precision displacement probe-the precision holographic optical probe (PHOP)-with the use of double holographic optical element (DHOE) technology. It is a novel noncontact method for the measurement and inspection of displacement and surface quality control. To improve the measurement resolution and linearity, the differential method for the PHOP is introduced. Infrared DHOEs are made by using a computer-generated hologram method. Mathematical models have been developed to analyze the performance of the probes. Computer simulations and experimental results have been obtained, showing sensitivity on the order of nanometers for these probes. The complexity and the size of the probes can be significantly reduced. They are both compact and inexpensive.
Usual commercial laser triangulation range sensor offers a noncontact means of measuring part dimensions for use with CMMs. However, there are several factors such as surface inclination and reflection variation which must be taken into account if accurate and reliable results are to be achieved. In this paper a precision laser triangulation range sensor with double detectors is proposed. The sensor can continuously and simultaneously detect the range of displacement and the surface inclination as well as generate a tracing signal to trace the surface normal. Using the summing signal processing method, the measurement error caused by surface inclination can be partly compensated. In this paper the derivation of the relation between the displacement of the surface and the centroid shift on the detector is presented. The computer simulation and experimental results show that the proposed sensor is able to provide the means with noncontact, high speed, high accuracy for profile measurement, even though for sculptured surface measurement on CMMs.
In this paper, an optical stylus displacement sensing principle has been studied, which serving a composite holographic optical element as an off-focus detection element. The mathematical models of optical measuring system have been established by means of Operator Algebra. The analysis results show that: the displacement of the tested surface is proportional to the image spot size on the detector. The sensibility of the sensor is obviously affected by the ratio of the equivalent focus length of the holographic optical element to the focus length of the objective lenses. To improve the measuring resolution and S/N ratio, so called off-plane detection method has been adopted. With which the output of the measuring results have a better linearity with the displacement of the tested surface. No less than 0.01 micrometers high resolution with linear measuring range of 5 micrometers have been obtained. Some measuring experiments are given.
Precision surfaces are needed in many fields. Usually they should be finished with nm order surface roughness as well as with a highly form accuracy. In order to know the textures of the machining surface and diagnose the machining process, the measurement should be carried out in the condition which is usually influenced by vibration disturbances. The purpose of this paper is to describe a new precision surface profiling probe - Integrated Holographic Optical Probe (IHOP) for precision surfaces profile measurement which is nearly insensitive to vertical vibrations. IHOP is an integrated sensor which serves a four sensors. It can be used in the differential mode to eliminate or to minimize errors caused by vibrations. In this first report, the computer simulation and experimental results are obtained. They show the sensitivity with the order of nanometers for this probe. The complexity and the size of the probe can be significantly reduced.
The purpose of this paper is to describe a new precision displacement sensor--Compact Precision Holographic Optical Probe--with the use of holographic optical element (HOE) technology. It is a novel non-contact method for the measurement and inspection of displacement and surface quality control. The IR HOEs are made by using a computer generated hologram method. A mathematical model has been developed to analyze the performance of the probe. The initial experimental results are obtained. The probe is both compact and inexpensive.
The purpose of this paper is to describe a new precision displacement sensor--Multi-Beam Holographic Optical Sensor (MBHOS) for control of diamond turning--with the use of holographic optical element (HOE) technology. MBHOS is actually an integrated sensor which serves as three sensors. It can be used with the function of a single sensor to be a feedback component in closed loop control system and it can be used in the differential mode to detect the angular components of the micro-tool servo motion and to eliminate or to minimize the vibration errors with the function of three sensors. The ir HOEs are made by using a computer generated hologram (CGH) method. A computer simulation method is used to analyze the performances of this integrated sensor system. The initial experimental results of the MBHOS are obtained. The MBHOS is both compact and inexpensive.
Off-focus detection methods have been successfully applied in measuring micro-displacement and surface roughness. but there are imperfects in these methods. For example range of measurement is too small and accuracy of measurement is seriously affected by the inclination of measured surface To overcome these problems focus-tracing methods have been developed. In this paper a moving voice coil is used as focus actuator to drive the object lens up and down. The basic composition and characteristics of the actuator are described The features of displacement and frequency response of the probe are analysed. Some experiment results are given.
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