Papers by Keyword: Optical Inspection

Abstract: 3-channel analysis technique consisting of optical inspection, photoluminescence and X-ray topography methods for defect inspection of SiC epitaxial wafers has been investigated. The effectiveness of SiC wafer inspection image correction to enable automatic defect analysis is verified. Next, it is shown that the 3-channel analysis technique improves SiC defect inspection accuracy compared to conventional 2-channel analysis one.

Abstract: The paper presents a method of optical inspection of manufacturing processes in the visible band. The presented model of the test bench was based on a monochrome CCD camera that allows one to conduct research in the field of digital image analysis. The wavelet transform was proposed for the detection of objects. This wavelet transform allows examining pictures with use of textures. The article presents an analysis of the results of experiments for selected objects using the proposed method, allowing the evaluation of the correctness of classification. In the article, the advantages of using the proposed method in a sample manufacturing process to recognizing surface defects (e.g. cracks or scratches) is discussed.

Abstract: The article presents the structure and operation of the developed system for graphic personalisation of cards and paper sheets. The system is responsible for the input of unique graphics in the form of prints corresponding with suitable data recorded in the memory of a microprocessor. In the verification process, an electronic record is compared with alphanumerical information, and the conformity of digital graphics with the print is checked. The system was used in the construction of a process line for producing RFID-secured documents. The system has a modular structure and is composed of two modules responsible for the prints and automatic verification of graphic personalisation. The printing module enables the application of the print in the form of alphanumerical signs or unique graphic symbols and a barcode, which is conducted according to the structure of the database from which information on personalisation is obtained. The verification module compares the electronic record from the microprocessor with alphanumerical information and checks whether digital graphics agree with the print. Printing is performed using an inkjet printhead, whereas for the verification process, a digital line scan camera is applied. Mechatronic positioning systems enable the printhead and camera shift freely along the print and inspection area and allow changes in positioning speed parameters.

Abstract: The article presents the optical inspection method for the correct assembly of bearings with rolling elements in the form of balls. During the assembly process, faults can occur of incomplete fill of the rolling elements in a bearing cage or a lack of rivets for fixing both parts of the cage. These are critical defects, disqualifying the bearing from the operation. In order to detect these faults, the method of backlighting was used in the form of a modular LED panel illuminator located under the inspected bearing. The chosen method of lighting provides a high contrast and good sharpness with a simultaneous low sensitivity to contamination that may arise in the field of view of the camera. In order to verify the developed method, an experimental automated research stand was made. For vision inspection, a modular vision controller with a monochromatic CCD camera was used. Due to the range of bearings subjected to vision inspection, the algorithm of the program allows automatic detection of the bearing type based on its characteristics. The operation of the vision system was presented for each of the individual stages of the inspection process. The functions used in the field of computer-based image processing and analysis were described. Examples of bearing inspections, with use of the developed method, were presented.

Abstract: The FSW method is a modern and still not very common method for joining materials by mixing them after plasticising with a special tool. The rotary motion of the tool and its pressure against the welded surface causes friction and, as an effect, local heating of the material that then causes plasticisation. Then the tool moves linearly along the trajectory of welding, while the stem causes the mixing of materials and tool’s shoulder concentrates and presses the material in the produced weld. An important feature of the process is that the material does not pass to the liquid phase and remain in the solid phase. This method allows the combination of non-welding and difficult to weld materials, including combining different materials (dissimilar). The FSW method is a new method and there are no tools to assess the quality of the process, especially on-line, that is in the making of the weld. Currently, the research methods used include point temperature measurement and measurement of forces on the tool performed during welding, and metallographic methods that are destructive can be used after the weld. This article presents the authors’ method for monitoring the Friction Stir Welding (FSW) processes with use of a multi-spectral vision method. The monitoring method uses the system built of two visual channels that work in different light bands; hence, the name of the method is multi-spectral. The main component of the system is an infrared camera that is used for the observation of the temperature distribution on the surface of the welded materials. The second visual channel uses the line-scan visual band camera for recording the image of the surface of the weld. Such observation allows the detection of weld defects and non-compliances, which include excessive burrs, discontinuities, uneven edge of the weld, as well as the subsurface faults such as cavities and sub-surface discontinuities. In addition, the temperature of the process is monitored to prevent under-and over-heating, which may result in a weak joint or cracks in the material. The presented method is applied for monitoring the FSW process and presents a worldwide novelty.

Abstract: The paper presents a method of optical inspection of manufacturing processes in the visible band. The presented model of a test bench was based on a monochrome CCD camera that allows you to conduct research in the field of digital image analysis. The wavelet transform was proposed for the detection of objects and was compared with a Fast Fourier Transform (FFT). The article presents an analysis of the results of experiments for selected objects using the proposed method, allowing the evaluation of the correctness of classification. The paper also presents an analysis of the efficiency of the compared methods. In the article, the advantages of using the proposed method in the sample manufacturing process have been discussed.

Abstract: Faster and more accurate optical aspheric testing methods are required in many technical fields. A digital moiré phase shifting interferometer (DMPSI) with partial compensation lens (PCL) is proposed. With digital phase shifting technique, only one shot of interferogram is required, so the system structure is simpler with lower sensitivity to the environmental vibration. PCL is designed to enlarge the measurement range of asphericity. A DMPSI prototype in Fizeau configuration has been developed. After calibration, spherical surface is tested with accuracy comparable to Zygo interferometer.

Abstract: he article presents a measurement system designed for “on-line” high throughput simultaneous optical inspection of large set of geometrical parameters (more than 1000 points) defining geometry of some complex surface. The measurement system is based on the distributed network of optical distance sensors. Specialized optical sensor as basic system element was developed for this purpose. Among its features are the following: non-contact measurement, high optical and electromagnetic noise immunity, small footprint, and mass-production oriented. The system allows us to measure up to 1700 linear distance parameters simultaneously in the range of 40mm, with accuracy (3σ) of 0.1 mm and sampling rate of at least 103 Hz.

Abstract: A new dry cleaning methodology named laser shock cleaning and optical inspection technique has been applied not only to remove the particles from the surfaces of image sensors but also to inspect the surfaces automatically before or after the cleaning. In the packaging of CMOS and CCD image sensing modules, the particles generated during the assembly process should be removed from the surfaces of image sensors in order to ensure clear image as well as to enhance the yield. The different kinds of particles were removed from the surfaces by the laser shock cleaning technique which utilizes the airborne shock wave induced by intense laser pulse. For the quantitative evaluation of cleaning performance, number, shape and size of the particles on the surfaces of image sensors were measured by vision inspection technique before and after cleaning. It was found that most particles on the surfaces were successfully removed after the treatment of laser-induced shock waves. The average removal efficiency of the particles was over 95 %. It is interestingly found that the remaining particles after the cleaning are based on organics, which are probably attached during the bonding process.

Abstract: This paper deals with the measurement and the detection of errors in the threedimensional geometry of high-strength structure components. Firstly different geometrical measuring systems and their usability for the measurement of high-strength structure components are discussed. An optimized solution is suggested, an adaptive projection method based on pattern projection is introduced. The technique takes care of the special properties of high-strength structure components within the production process. The measurement procedure is divided into two steps. Within the adaptation-step the luminescence and the resolution of the projected pattern is adapted on the measured object. The actual picture is taken and calculated in a second step in order to avoid vibrations. The paper concludes with a description of the data processing procedures necessary in order to evaluate the correctness of the measured structure and describes how a 100% geometrical quality control can be achieved using the described methods.