Smooth Surface Visual Imaging Method for Eliminating High Reflection Disturbance

Abstract

At present, visual imaging is widely applied for surface defects such as bumps and scratches in the manufacture of precise parts with a highly reflective surface. However, the high light reflection and halo disturbance as a result of the illumination in visual imaging exert a direct influence on the accuracy of defect detection. In this regard, the present paper develops an adaptive illumination method based on space–time modulation for a visual imaging system. Furthermore, a digital micro-mirror device (DMD) is employed to realize the pixel-level spatiotemporal modulation of illumination. Then, in combination with the illumination intensity feedback of charge coupled device (CCD), the time-space ratio is adjusted automatically to achieve adaptive uniform illumination and effectively suppress the high light reflection and halo disturbance of highly reflective surfaces. The experimental results show that, in terms of restraining high light disturbance, the visibility and accuracy of visual imaging are improved.

Defect detection for highly reflective rotary surfaces: an overview

“…Experiments verified the effectiveness of this method. Shao et al proposed a method for unfolding the surface of a cylinder based on a high-precision turntable [31]. In this study, the authors placed the inspected parts directly on a high-precision turntable.…”

“…Shao et al designed an adaptive optical lighting system and used the striped illumination formed on the surface of the measured workpiece to realize the visual detection of highreflection rotary surface defects. This method could effectively suppress the intensity over-exposure and halo interference caused by high reflection interference during the defect detection process [31].…”

“…(a) Single sensors: This kind of sensor is used to sense real information about HRRS defects. In HRRS DDSs, various single sensors have been used such as fiber optic sensors [11][12][13], an ultrasonic probe [14], capacitance sensors [ 15,16], vision sensors [3,4,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], etc. It is difficult to achieve rapid, accurate and comprehensive detection of HRRS defects using single sensor-based detection methods.…”

Stainless steel cylindrical pot outer surface defect detection method based on cascade neural network

“…This work serves as a valuable reference for detecting imperfections on other similarly smooth cylindrical surfaces. In a related study, Shao et al [6] tackled issues arising from intense light reflection and halo interference on precision components. They employed a digital micro-mirror device to achieve pixel-level spatiotemporal modulation of the illumination system.…”

Method and Device of All-in-Focus Imaging with Overexposure Suppression in an Irregular Pipe

“…However, the highly reflective and freely changing structural features quickly lead to overexposures, which reduce the utility of the acquired information for fault detection. To mitigate these negative effects, Shao [ 23 ] devised a digital micro-mirror device (DMD) to realize pixel-level spatiotemporal modulations of illumination, the principle of which is that the reflected light (adaptive stripes with spatiotemporal modulation) modulated by DMD is projected through a triangular prism, mirror, and projection lens onto a workpiece with a highly reflective surface, and a uniform illumination is formed on the workpiece surface to highlight the defect information. Liu [ 24 ] introduced a study that uses a coaxial light source to obtain the first coaxial optical images to identify the bearing center coordinates and text information; then, under the multiangle light, images are obtained at different angles in turn, and all the defects of the bearing can be highlighted after image fusion.…”