Disparity Surface Reconstruction Based on a Stereo Light Microscope and Laser Fringes

Abstract

Microscopic vision systems based on a stereo light microscope (SLM) are used in microscopic measuring fields. Conventional measuring methods output the disparity surface based on stereo matching methods; however, these methods require that stereo images contain sufficient distinguishing features. Moreover, matching results typically contain many mismatched points. This paper presents a novel method for disparity surface reconstruction by combining an SLM and laser measuring techniques. The surfaces of small objects are scanned by a laser fringe, and a stereo image sequence containing laser stripes is obtained. The central contours of the laser stripes are extracted, and central contours are derived for alignment. A disparity coordinate system is then defined and used to analyze the relationship between the motion direction and reference plane. Next, the method of aligning disparity contours is proposed. The results show that our method can achieve a precision of ±0.5 pixels and that the real and measured shapes described by the disparity surface are consistent based on our method. Our method is confirmed to perform much better than the conventional block-matching method. The disparity surface output obtained by our method can be used to measure the surface profiles of microscopic objects accurately.

Surface Reconstruction of Microscale Objects Based on Grid-Patterned Structured-Light Measurements

“…The combination technique of a binocular stereovision system and a fringe-patterned structured light had some advantages. In this kind of technique, two telecentric microscope lenses (Hu et al, 2019) or a stereo-light microscope (Wang, 2018) were used to develop the measurement system, and the fringe-patterned structured light was emitted through either the projection equipment or a laser light source, which was used to either calibrate the system or as the mark of projection. The height distribution of the surface was calculated based on the stereo-matching principle and disparity.…”

“…In relevant research, the measured height of the samples was mostly in the millimeter scale, involving small resistors, capacitors, small stones, clamp tips, etc. (Wang, 2018). This kind of technique has advantages due to its simplicity of reconstruction, but the resolution (the vertical distance corresponding to a disparity pixel) in the vertical direction as it relates to the height distribution is dependent on the structure of the system.…”

“…For the morphology reconstruction of microscale objects, the accuracy of coordinate reconstruction is very important. In this kind of system, the synchronization of the image sequence of the fringes must be considered (Wang, 2018). Relative movement can easily cause measurement errors, so precise calibration and error correction are crucial.…”

Orthogonality Measurement of Three-Axis Motion Trajectories for Micromanipulation Robot Systems

“…In recent years, laser displacement sensors based on the principle of triangulation have developed rapidly, with the emergence of point sensors, stripe-structured light sensors, etc., which can detect the position of a single point or multiple simultaneously and are being increasingly widely used for many tasks such as shape reconstruction, geometric dimension measurement, distance measurement, etc. [28][29][30][31]. The design of the laser displacement sensor is modularized and compact.…”

Design of thin‐structured‐light projection system for small‐height measurement

“…The line-structured light source can directly generate fringes and project the line-structured light directly on the surface of the small object. But at present, the minimum width of the fringe can reach tens of microns, for example, Wang (2018) reconstructed the 3D shape of some small-height objects (such as small resistance, small gravel, micro clamp tip, etc.) based on line-structured laser source and stereo vision technique, and the width of line-structured fringe can reach 25 μm (Supplementary Videos S1,S2, S3,S4,S5).…”