Characterization of Surface Micro-Roughness by Off-Specular Measurements of Polarized Optical Scattering

Abstract

The characterization of surface micro-roughness is investigated by using off-specular measurements of polarized optical scattering. In the measurement system, the detection angles of optical scattering are defined by the vertical and level scattering angles. The rotating mechanism of angles is controlled by stepper motors. Waveplate and polarizer are used to adjust light polarization and detection. We conduct the optical scattering measurements by using four standard metal sheets of surface roughness. The nominal values (Ra) of standard micro-roughness are 1.6 μm, 0.8 μm, 0.4 μm, and 0.1 μm, respectively. Samples with different surface roughness are evaluated with the utilization of laser sources at three incident wavelengths. These polarized images are analyzed using a computer program to obtain the distribution of light intensity. The results show great correlation between the metal surface roughness and polarization states. This measurement system can be used to quickly and accurately distinguish between different surfaces and properties.

Analysis of visualization through depolarization via light scattering related to surface structure in visible and infrared light

“…Light scattering-induced depolarization is a frequently observed occurrence in polarization imaging. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] To investigate the light scattering effect, we measured the surface structure of the meter's surface using a laser microscope (VKX3000; KEYENCE Inc.). The observed surface structures between the text part and the black board part are shown in Fig.…”

“…A detailed analysis of this phenomenon forms the basis for the societal implementation of polarization imaging in various scenarios. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Various parts of the living body induce polarization changes through light scattering, enabling distinctive visualization of the corresponding areas. Gurjar et al achieve quantitative analysis of nuclear size, degree of pleomorphism, degree of hyperchromasia, and epithelial cell nuclei by illuminating the specimen with white linearly polarized light through a color filter and performing imaging through a cross-Nicol arrangement of polarizers to capture the backscattered light.…”

“…The study demonstrates a strong correlation between metal surface roughness and polarization states. 17) Although not specifically focused on polarization imaging for visualization research, a novel approach has been proposed to restore polarization images based on the transmitting characteristics of an object's polarization information, aiming to mitigate image degradation in imaging through scattering media. 19) Recently, we have investigated the influence of illumination light wavelength and polarization in polarization imaging of birefringent media placed behind scattering structures.…”

A Fast and Low-Power Detection System for the Missing Pin Chip Based on YOLOv4-Tiny Algorithm

“…However, traditional manual detection methods are inefficient and unable to meet the growing demand for high-speed and accurate detection in modern chip production [2] and are gradually being replaced by automatic detection technology. In traditional machine vision detection, the automatic optical inspection method has gained popularity for quality detection of PCBs in electronic devices using optical sensors and computer technology [3,4]. However, this approach still presents urgent problems with the measurement of key geometric dimensions of chip pins [5,6].…”

Automatic Detection of Chip Pin Defect in Semiconductor Assembly Using Vision Measurement

“…Previously, the quality of the chip package was monitored manually, which has low efficiency, bad reliability and cannot meet the requirements of high speed assembly production [3]. With the development of optical sensors and computer technology, quality detection of the PCBs using the automatic optical inspection (AOI) method has become a main stream for the electronic devices in SMT [4]- [6]. Especially, the measurement of key geometric dimensions of chip pins, including the width distance of a pin, the distance between adjacent pins and the height of pins (whether there is abruption, warping, collapsing or not) and other key dimensions, is an urgent issue to be solved in the current chip packaging process [7]- [8].…”