An edge-from-focus approach to 3D inspection and metrology

Best Paper Award 2015We propose an edge-based depth-from-focus technique for high-precision non-contact industrial inspection and metrology applications. In our system, an objective lens with a large numerical aperture is chosen to resolve the edge details of the measured object. By motorizing this imaging system, we capture the high-resolution edges within every narrow depth of field. We can therefore extend the measured range and keep a high resolution at the same time. Yet, on the surfaces with a large depth variation, a significant amount of data around each measured point are out of focus within the captured images. Then, it is difficult to extract the valuable information from these out-of-focus data due to the depth-variant blur. Moreover, these data impede the extraction of continuous contours for the measurement objects in high-level machine vision applications. The proposed approach however makes use of the out-of-focus data to synthesize a depth-invariant smoothed image, and then robustly locates the positions of high contrast edges based on non-maximum suppression and hysteresis thresholding. Furthermore, by focus analysis of both the in-focus and the out-of-focus data, we reconstruct the high-precision 3D edges for metrology applications

Depth from Refraction Using a Transparent Medium with Unknown Pose and Refractive Index

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Single-lens multi-ocular stereovision using prism

Ph.DDOCTOR OF PHILOSOPH

Programmable Spectral Source and Design Tool for 3D Imaging Using Complementary Bandpass Filters

An endoscopic illumination system for illuminating a subject for stereoscopic image capture, includes a light source which outputs light; a first complementary multiband bandpass filter (CMBF) and a second CMBF, the first and second CMBFs being situated in first and second light paths, respectively, where the first CMBF and the second CMBF filter the light incident thereupon to output filtered light; and a camera which captures video images of the subject and generates corresponding video information, the camera receiving light reflected from the subject and passing through a pupil CMBF pair and a detection lens. The pupil CMBF includes a first pupil CMBF and a second pupil CMBF, the first pupil CMBF being identical to the first CMBF and the second pupil CMBF being identical to the second CMBF, and the detection lens includes one unpartitioned section that covers both the first pupil CMBF and the second pupil CMBF

Endoscope and System and Method of Operation Thereof

An endoscope including a rigid section having opposed first and second ends and an opening situated between the first and second ends, the rigid section defining a longitudinal axis; a handle portion coupled to a first end of the rigid section and having first and second scissor-type handles suitable for grasping by a user; and a base part situated at the second end of the rigid section and coupled to the first handle of the scissor-type handles such that displacement of the first handle causes a rotation of the base part

Single-channel stereoscopic imaging system using rotating deflector

Dept. of Biomedical Engineering/석사In a conventional dual-channel stereoscopic imaging system (SIS), two cameras are often used to take images at different visual orientations, creating a three-dimensional (3D) image. Because two cameras are used, visual fatigue may be caused by differences between the cameras involving temporal synchronization, geometrical calibration, and color balance. Furthermore, owing to its mechanical composition, the imaging system is generally bulky.To eliminate the possible limitations of current conventional dual-camera SISs, research was conducted to develop a 3D SIS using a single camera. Its purpose is to create image disparity (ID), a key factor in producing stereoscopic images. Using a transparent rotating deflector (TRD), ID was mimicked assuming that light refraction through the TRD would create the necessary ID.First, the system’s efficacy was tested using a thorough simulation and experiment based on Snell’s law. Light propagation through the TRD was modeled using ZEMAX. The ID was calculated for various TRD refractive indices and thicknesses. On the basis of the simulation and calculation, a TRD-based SIS (TRD-SIS) was developed using manual rotation of the TRD. Second, a real-time TRD-SIS was set up to allow real-time stereoscopic imaging and display. A complementary metal–oxide–semiconductor (CMOS) camera was used along with a stepping motor controlled by a microcontroller unit. The acquiredimages were visualized in 3D using an active 3D method. Finally, the system was evaluated in terms of two factors: (1) temperature generation and (2) the image characteristics. The temperature changes in the optical components were measured at the motor surface and motor driver. The image characteristics were evaluated by calculating the coefficient of variation of acquired images of a white reflectance target. In addition, a method of controlling heat generation using a heat sink and motor fan was devised.ope

Stereo Imaging Miniature Endoscope with Single Imaging Chip and Conjugated Multi-Bandpass Filters

A dual objective endoscope for insertion into a cavity of a body for providing a stereoscopic image of a region of interest inside of the body including an imaging device at the distal end for obtaining optical images of the region of interest (ROI), and processing the optical images for forming video signals for wired and/or wireless transmission and display of 3D images on a rendering device. The imaging device includes a focal plane detector array (FPA) for obtaining the optical images of the ROI, and processing circuits behind the FPA. The processing circuits convert the optical images into the video signals. The imaging device includes right and left pupil for receiving a right and left images through a right and left conjugated multi-band pass filters. Illuminators illuminate the ROI through a multi-band pass filter having three right and three left pass bands that are matched to the right and left conjugated multi-band pass filters. A full color image is collected after three or six sequential illuminations with the red, green and blue lights