Localized fluid flow measurements with an He-Ne laser spectrometer

This tutorial reviews various noncontact optical sensing techniques that can be used to measure distances to objects, and related parameters such as displacements, surface profiles, velocities and vibrations. The techniques that are discussed and compared include intensity-based sensing, triangulation, time-of-flight sensing, confocal sensing, Doppler sensing, and various kinds of interferometric sensing with both high- and low-coherence sources.

Optical methods for distance and displacement measurements

Методы подавления шумов и помех в электронных системах. (Noise reduction techniques in electronic systems)

In this paper, the role and importance of the machine vision systems in the industrial applications are described. First understanding of the vision in terms of a universal concept is explained. System design methodology is discussed and a generic machine vision model is reported. Such a machine includes systems and sub-systems, which of course depend on the type of applications and required tasks. In general, expected functions from a vision machine are the exploitation and imposition of the environmental constraint of a scene, the capturing of the images, analysis of those captured images, recognition of certain objects and features within each image, and the initiation of subsequent actions in order to accept or reject the corresponding objects. After a vision system performs all these stages, the task in hand is almost completed. Here, the sequence and proper functioning of each system and sub-systems in terms of high-quality images is explained. In operation, there is a scene with some constraint, first step for the machine is the image acquisition, pre-processing of image, segmentation, feature extraction, classification, inspection, and finally actuation, which is an interaction with the scene under study. At the end of this report, industrial image vision applications are explained in detail. Such applications include the area of automated visual inspection (AVI), process control, parts identification, and important role in the robotic guidance and control. Vision developments in manufacturing that can result in improvements in the reliability, in the product quality, and enabling technology for a new production process are presented. The key points in design and applications of a machine vision system are also presented. Such considerations can be generally classified into the six different categories such as the scene constraints, image acquisition, image pre-processing, image processing, machine vision justification, and finally the systematic considerations. Each aspect of such processes is described here and the proper condition for an optimal design is reported.

Design and application of industrial machine vision systems

In this work, a surface finish method for parts built-up by selective laser sintering (SLS) is presented One of the main drawbacks of the SLS technique is the high surface roughness of resulting parts Therefore, parts have to be polished to be valid for operation conditions Polishing processes are usually based on manual abrasive techniques However, in the present paper, a surface polishing method based on laser irradiation is presented The laser beam melts a microscopic layer on the surface, which re-solidifies under shielding gas protective conditions, resulting in a smoother surface Laser-polishing tests for lines, planar surfaces and inclined planes have been performed, with satisfactory results in all the cases The experimental tests were carried out on sintered test parts with an initial roughness of 75–78 μm Ra The tested material is a commercial alloy denominated LaserForm ST-100©, composed by sintered stainless steel and infiltrated bronze that it is used mainly for the constitution of injection moulds Experimental results present final surface roughness below 149 μm Ra, which represent an 801% reduction of the mean roughness Finally, a complete analysis of test probes and its metallurgical composition is presented Considering that the material presents a non-homogeneous structure, the polished surfaces present slightly higher hardness values and are more homogeneous than the initial ones Thus, polished surfaces do not present any heat affected zone or cracks, which could cause failure during the part operation

Laser polishing of parts built up by selective laser sintering

Design and operation of a fiber optic sensor for liquid level detection

Design and operation of a double-fiber displacement sensor

In this article design and operation of a plastic optical fiber (POF) sensor based on the unconventional light leakage from one fiber to another one causing intensity modulation are presented. The dominant loss mechanism was found to be the evanescent loss and based on this phenomenon the optical fiber sensor was designed. The penetration depth of evanescent wave as a function of different refractive index of cladding was calculated. Operation of this sensor was tested as a liquid level sensor for different liquids and the experimental results are compared. The dry (air interface layer) and wet output (liquid interface layer) signals for this probe were measured for a series of measurements and important factors concerning sensor operation are described. The precision of measured values, reproducibility of the results (1.35% error), and the stability of sensing operation as a function of time at different launching powers are also reported (0.85% error). The reported results for this design are promising and verify the successful operation of such a device as a liquid level probe and also as an on/off level switch.

Hossein Golnabi

Papers

Design and application of industrial machine vision systems

Design and operation of a fiber optic sensor for liquid level detection

Design and operation of a double-fiber displacement sensor

Design and performance of a plastic optical fiber leakage sensor

Carbon nanotube research developments in terms of published papers and patents, synthesis and production