A visual feedback system for micromanipulation with stereoscopic microscope

2018

Microsc Microanal

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.

Section: Introductionmentioning

confidence: 99%

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

2018

Microsc Microanal

“…He set up a complex parameter calibration method to obtain high‐precision reconstruction data. Sano, Hidekazu, Hiroshi, Takeshi, and Hidekim () and Seok, Kyunghwan, and Deok‐Ho () used SLM stereovision to construct microinjection and microassembly systems. They analyzed the projection principle and proposed a stereovision model, which is used to calculate the world coordinates and guides the motion of micromanipulator.…”

Section: Introductionmentioning

confidence: 99%

A stereovision model applied in bio‐micromanipulation system based on stereo light microscope

Microscopy Res & Technique

2017

A bio-micromanipulation system is designed for manipulating micro-objects with a length scale of tens or hundreds of microns based on stereo light microscope. The world coordinate reconstruction of points on the surface of micro-objects is an important goal for the micromanipulation. Traditional pinhole camera model is applied widely in macrocomputer vision. However, this model will output bad data with remarkable error if it is directly used to reconstruct three-dimensional world coordinates for stereo light microscope. Therefore, a novel and improved pinhole camera model applied in bio-micromanipulation system is proposed in this article. The new model is composed of binocular-pinhole model and error-correction model. The binocular-pinhole model is used to output the basic world coordinates. The error-correction model is used to correct the errors from the basic world coordinates and outputs the final high-precision world coordinates. The results show that the new model achieves a precision of 0.01 mm in the X direction, 0.01 mm in the Y direction, and 0.015 mm in the Z direction within a maximum reconstruction distance of 4.1 mm in the X direction, 2.9 mm in the Y direction, and 2.25 mm in the Z direction, and that traditional pinhole camera model achieves a lower and unsatisfactory precision of about 0.1 mm.

“…And after images synthesis, the 3D picture can be obtained. Therefore, stereomicroscopes [5][6] [7] [8] are used widely in microassembly.…”

Section: Introductionmentioning

confidence: 99%

Pose measurement method with six parameters for microassembly based on an optical micrometer

Zhang

et al. 2009

SPIE Proceedings

This paper presents a new pose measurement method of microminiature parts that is capable of transforming one dimension (1D) contour size obtained by optical micrometer to three dimension (3D) data with six parameters for microassembly. Pose measurement is one of the most important processes for microminiature parts' alignment and insertion in microassembly. During the past few years, researchers have developed their microassembly systems focusing on visual identification to obtain two or three dimension data with no more than three parameters. Scanning electronic microscope (SEM), optical microscope, and stereomicroscope are applied in their systems. However, as structures of microminiature parts become increasingly complex, six parameters to represent their position and orientation are specifically needed. Firstly, The pose measurement model is established based on the introduction of measuring objects and measuring principle of optical micrometer. The measuring objects are microminiature parts with complex 3D structure. Two groups of two dimension (2D) data are gathered at two different measurement positions. Then part pose with 6 parameters is calculated, including 3 position parameters of feature point of the part and 3 orientation parameters of the part axis. Secondly, pose measurement process for a small shaft, vertical orientation determination, and position parameters obtaining are presented. 2D data is gathered by scanning the generatrix of the part, and valid data is extracted and saved in arrays. A vertical orientation criterion is proposed to determine whether the part is parallel to the Z-axis of the coordinate. If not, 2D data will be fixed into a linear equation using least square algorithm. Then orientation parameters are calculated. Center of Part End (CPE) is selected as feature point of the part, and its position parameters are extracted form two group of 2D data. Finally, a fast pose measurement device is developed and representative experiments are carried out. Results show that the measurement method could obtain pose of complex 3D micro parts fast and accurately, and can meet the demand of microassembly system.