Inner Hole Range Sensor With Laser Triangulation

The application of hole shaft parts play a vital role in the national production and life, andthe detection of hole parts is more difficult than the detection of shaft parts. The hole’sdetection is used mostly mechanical testing at present measurements, however, hole parts’internal surface morphology or some other parameters can not be detected by mechanicaltesting conveniently and fast. In view of this situation, this paper put forward a new lasertriangulation based on trapezoid prism, and we designed a laser triangulation hole measuringsensor, which can detect the inner hole parts’ internal surface morphology and wall surfaceparameters.The sensor based on the characteristics that when measure the inner parts, the physicalspace is limited, and we put forward a new method that the sensor uses the trapezoid prismrefraction-such characteristics limiting the light path in a narrow space, meanwhile, combineswith the laser triangulation’s advantages in Geometric measurement. This method can bettersolve the problem of inner hole detection, according to the sensor’s design and production, inthis paper we have done the following work:1. According to the characteristics of the inner hole’s test and the reason about ordinaryoptical measurement method can not measure the hole parts surface parameters, we made acomprehensive analysis, and put forward a measuring method which used the trapezoidalprism’s total reflection.2. Puts forward a kind of optical structure which bilateral symmetry of trapezoidal prismsand imaging lens, we make optical analysis and optical simulation about this optical structureand make a comprehensive analysis about the structure’s shortcomings, then, propose severalimprovement plans according to the faults.3. Sure a reasonable optical measurement scheme and design some mechanical structuresto fix the optical element according to the relative position of optical element, built a set ofexperimental platform, and at last assemble and debug the sensor according to the designrequirements.4. Doing algorithm design and interface design using the software of MATLAB, and thencalibrating sensor. Then doing repeatability tests, some precision experiments, accuracyanalysis and verification about the final results of the measurement. 5. According to the influence of tilt surface on the result of the measurement, we designeda tilt correction algorithm.Experimental results indicated that the measurement precision can reach2um whenmeasuring range between0and1.6mm. This sensor can better solve the problem of thephysical space is limited, combined with the characteristics of laser triangulation technique,can achieve the requirements of precision measurement for inner hole surface parameters.