Measure distance with accuracy from a few microns to a few millimetres, over a range of a. France has developed and been using an optical triangulation method otm which uses the measurement of tank angles to determine the tank diameter. The inspection by optical, noninvasive methods for analyzing surface objects or those surfaces, is also introduced. Oct 15, 1985 optical triangulation apparatus and method.
Single point optical triangulation is an easy to use method of measuring distances to objects without touching them and requires little operator knowledge or supervision. Triangulation for stereo cameras with parallel optical axes, focal length f, baseline b, corresponding image points xl,yl and xr,yr, the location of the 3d point can be derived from previous slides equations. A new displacement measurement system is described in this paper according to the basic principles of traditional laser triangulation method. An imagebased laser triangulation width model applied in. Three independent ccds, which are distributed uniformly along the optical axis, are used to achieve subsection measurement. In the system 10, a workpiece 12 is positioned to receive the light output of a light source 14. In most cases an optical triangulation sensor is mounted near the top of the swinging door frame, inside a long extruded aluminum tube with an optical window facing the floor. Again using the known diameter of the earth as a baseline, basic provided the means of calculating distances to the planets and closest stars. They are noncontact height or range measurement devices. Optical triangulation apparatus and method general. The official version is available for download from the acm digital library. Optical triangulation position sensors use reflected waves to pinpoint position and displacement. Calibration of upright cylindrical tanks using the opticaltriangulation method ansiapi mpms ch.
Pears1 department of engineering science, university of oxford. Development of a diffractiontype optical triangulation sensor. This tutorial gives an overview of single point optical triangulation. Kr20110017158a a measuring apparatus and method using. Single point optical triangulation is an easy to use method of measuring distances to objects without touching. A distant object is sighted from two well separated locations. In order to solve this problem it is necessary to know the parameters of the camera projection function from 3d to 2d for the cameras involved, in the simplest case represented by the camera matrices. An optical triangulation method for noncontact profile measurement. In the standard geometry, which is the most commonly employed method, the laser line is projected perpendicular to the nominal measurement x, y plane. Optical triangulation gear inspection diffracto ltd. The triangulation method discussed in the previous section is used to calculate the effective distance from sensor to surface. Machine vision systems based on 3d triangulation are employed in a range of industries from automotive and electronics manufacturing to lumber mills.
Monthly espensea of these parties ull tu high 85 315. Range sensors based on active optical triangulation are currently among the. Oct 09, 2000 the current measuring methods have the problems such as low precision and low efficiency. An opticaltriangulationbased method for measurement of. A noncontact optical microtopographer based on an active, discrete triangulation procedure has been under development for some time at the physics department of the university of minho. Laserbased 3d triangulation systems can be configured in numerous ways to optimize the performance of a machine vision system. To use to measure distances, a surveyor must be familiar with trigonometry, the mathematics of geometrical angles. The optical triangulation method is another technology that accomplishes calibration from ground level. See this course at siggraph 2009 on wed august 5 from 8. The range of the traditional measuring method is enlarged by measuring in sections. Design of optical triangulation devices sciencedirect. Zhaojun xu, a, shenjian ni, a maolin yu, b and lei huang b. Us8160334b2 method for optical measurement of objects.
Pdf optical triangulationbased microtopographic inspection of. For optical triangulation systems, the accuracy of the range data depends on proper interpretation of imaged light reflections. Understanding laserbased 3d triangulation methods vision. Adis proprietary photonics technology enables a new method of object location and triangulation, providing a viable alternative to ranging and. A displacement measurement system based on optical. High requirement on robustness and speed the measurement technology of today has achieved accuracy and processing performance which allows an integration of acquisition and analysis in online production processes. The imaging lens receives the scattering light, and images the light on the sensitive area of position detector ccd of light spot. They allow a fast and accurate determination of surface profiles, while consisting of relatively simple hardware and software configurations. At least one further shutter means is used to produce a further pattern and to project the further pattern as a further. Optical triangulation based microtopographic inspection of surfaces article pdf available in sensors 124. It is an electronic type of measurement, performed through a runtime measurement and a phase position measurement.
The optical triangulation method of distance measurement is used. For example, one such prior art optical triangulation system is shown in fig. Optical triangulation methods based on a laser light sheet and digital camera are used as a surface measurement technique in a wide range of. The vast and increasing range of surface types, tolerance requirements and measurement constraints demanded during the last decades represents a major research effort in the development of new methods, systems and metrological strategies. This technique can be illustrated by a simplified diagram as shown in fig. The mixing of data types, known as data triangulation, is often thought to help in validating the claims that. The characteristics of projected pattern techniques suggest that. Zhaojun xu, a, shenjian ni, a maolin yu, b and lei huang b the yield of sawn lumber has been largely governed by the identification accuracy of the external face width. The method is an alternative to other methods such as strapping ch. Although this technology has been in use for over twenty years, its speed and accuracy has increased dramatically in recent years with the development of geometrically sta. The current measuring methods have the problems such as low precision and low efficiency. Asimple methodfor order to effectively use the data from the camera and laser obtaining depth information using least square method is range finder, it is important to knowtheir relative position.
The noninvasive inspection of surfaces is a major issue in a wide variety of industries and research laboratories. Optical triangulation allows establishment of metrological systems, due to. Better optical triangulation through spacetime analysis. Surface inspection by an optical triangulation method. The most important characteristic of this configuration is that height variations in the object along the projected line do not produce a. The definition and analysis of surface profiles on reflective materials plays an important roll in. Digital speckle correlation method used in triangulation system with strong scattering situation will help to improve the. For optical triangulation systems that extract range from single imaged pulses at a time, variations in surface reflectance and shape result in systematic range errors. The advantage of the proposed sensor is that it obtains not only the linear displacement of a moving object but also its three angular motion errors. Of course, there are other possible ways to configure a 3d triangulation vision system that use a laser line source, but these are all typically variations of the four basic geometries just described and alternative methods will typically inherit the basic characteristics of the fundamental geometry from which they are derived table 1. A first shutter means is used to produce a first pattern and to project the first pattern as a first projection beam onto the object to be measured. Jul 10, 2017 adis proprietary photonics technology enables a new method of object location and triangulation, providing a viable alternative to ranging and time of flight for distance sensing, and featuring.
Optical triangulationbased microtopographic inspection of. Omc technical brief single point optical triangulation single point optical triangulation is an easy to use method of measuring distances to objects without touching them and requires little operator knowledge or supervision. These sensors use an optical transmitter to project light on the target. Calibration of upright cylindrical tanks using the optical triangulation method ansiapi mpms ch.
Petroleum and liquid petroleum products calibration of vertical cylindrical tanks part 3. Triangulation in social science triangulation is defined as the mixing of data or methods so that diverse viewpoints or standpoints cast light upon a topic. In the first in vivo demonstration of spectral triangulation, biocompatible composites of singlewalled carbon nanotubes in matrigel have been surgically implanted into mouse ovaries and then noninvasively detected and located. Optical triangulation allows establishment of metrological systems, due to its. The definition and analysis of surface profiles on reflective materials plays an. A measuring device and method using an optical triangulation technique are provided to simplify a structure since it is possible to produce parallel lights by the adding of a lens simply. This optical method deduces the threedimensional position of a shortwave ir emission source from the wavelengthdependent attenuation of fluorescence in tissues. New tank calibration method could be wave of the future oil.
This optical method deduces the threedimensional position of a shortwave ir emission source from the wavelengthdependent attenuation of. To reduces the optical noncontact measurement uncertainty, this paper presents an optical triangulation based method for measurement of. Optical triangulation apparatus and method general electric. Course notes an updated version of the course notes is maintained here see the links below. Optical triangulation systems have been commonly employed for measurement and for inspection applications. An 880 nm led light source emits a collimated, nearinfrared light beam. Sick laser triangulation sensors are even able to measure the thickness of transparent material. This method again provides a means for calibrating vertical cylindrical tanks using external measurement of angles with a theodolite or a laser theodolite. Optical triangulation position sensors selection guide. Solar panel substrate planeness measuring system by an. On the first view, this traditional photogrammetric. Using a single point sensor, it is possible to measure a single point distance, or with the addition of a motion system, a pointbypoint profile scan or surface scan is also possible. The developed sensor is composed mainly of a laser source, two quadrant detectors, and a reflective. Request pdf an optical triangulation method for noncontact profile measurement in this paper we present a triangulation based range sensor for noncontact.
Since no probe radius compensation, high efficiency, noncontact optical measurement methods get more and more attention, but the inspection uncertainty of optical measurement is usually between 30um to 50um. Optical 3d measurement by laser triangulation method machine vision in online production processes. A point in this subset is then a singularity of the triangulation method. Triangulation today is used for many purposes, including surveying, navigation, metrology, astrometry, binocular vision, model rocketry and, in the military, the gun direction, the trajectory and distribution of fire power of weapons. We propose a diffractiontype optical triangulation sensor based on the diffraction theorem and the laser triangulation method. Better optical triangulation through spacetime analysis brian curless marc levoy. A slit light3 is emitted from a slit unit2 and is projected to a target4. Electro optical triangulation rangefinder for contour measurement. Among the different systems developed, optical methods have the most important role and among those triangulationbased ones have gained a major status. Optical triangulation provides a noncontact method of position measurement. An optical triangulation method for noncontact profile.
This technique is sometimes referred to as structured light, and is the equivalent of an automated light section microscope. Us8160334b2 method for optical measurement of objects using. In computer vision triangulation refers to the process of determining a point in 3d space given its projections onto two, or more, images. The accuracy of optical triangulation methods hinges on the abil ity to locate the. Triangulation parties now consist of from two to nine observing units and the limit has bp no means been reached. In triangulation method measurement, for the situation of interface with low roughness and weak scattering, first step is to design the. Omc technical brief single point optical triangulation. Optical triangulation methods based on a laser light sheet and digital camera are used as a surface measurement technique in a wide range of applications. Further, we show that the principle generalizes to other scanning geometries. The angle is the triangulation angle while the laser plane in focus. In vivo optical detection and spectral triangulation of. Introduction optical triangulation devices have been used as distance sensors for robots and threedimensional profile measuring systems2. Optical 3d measurement by laser triangulation method.
The developed sensor is composed mainly of a laser source, two quadrant detectors, and a reflective diffraction. In some applications, it is desirable that the triangulation is independent of the coordinate system used. Preferred machine construction uses specialized geometrical relationships of sensor to gear, and specialized high accuracy photodetector array based laser triangulation sensor units of large range and high response speed. A method for optically measuring an object by means of an optical recording apparatus includes a triangulation method. Method of, and device for effecting contactfree measurement by. The mixing of data types, known as data triangulation, is often thought to help in validating the claims that might arise from an initial pilot study. Based on the actual engineering project of the solar panel substrate planeness measuring system, a solar panel substrate planeness noncontact measuring system is presented, which employs an optical triangulation method and bases on virtual precise datum. The basic measuring principle was outlined in maas et al. An imagebased laser triangulation width model applied in sawn lumbers external face measurement. However, even if we know no trigonometry at all, we can still solve the problem. Sep 14, 1982 optical triangulation systems have been commonly employed for measurement and for inspection applications.
The reflection of that light is focused via an optical lens on a light. This method is called trigonometric parallax and is based on the method of used by surveyors. A measuring method using an optical triangulation technique is as follows. The yield of sawn lumber has been largely governed by the identification accuracy of the external face width. Slides an updated version of the presentation slides is maintained here see the links below. This method of peak detection is very similar to the one presented in this paper for solving some of the problems of optical triangulation.