The key modules in a typical reverse engineering system consist of the acquisition, registration, and the integration of three-dimensional range surface data. We present a self-made optical digitizer that is used for quick acquisition of range images from multiple views, and describe a visualized registration scheme that can reliably provide an initial estimate for the fine registration of
multiple range images in a unified coordinate system. We also present an efficient approach for merging multiple range images in order to build a complete geometric model of the objects in 3-D space and experiment results showing the effectiveness of this approach in 3-D imaging and modeling for the application of reverse engineering
Accurate object location is a key problem in image measurement system and the basis of other image processing procedures. In our project, we aim to locate some chromatic round objects in a large field. In this paper, the regions where the objects lie are isolated firstly from the original image using their color information, in which the edges of objects are detected. A novel fast method for fitting an
ellipse to the edge points in the region is presented, by which the geometric distortion is calibrated by the ellipse model calculated linearly according to the position of the region. And the position of object with the precision of one pixel is obtained through edge fitting. Finally the accurate data in 1/5 pixel result from subpixel subdivision.
This paper reports on development innovations at the Center for Optics Manufacturing (COM) that incorporate computer-aided deterministic manufacturing technology to produce highly precise optics. COM developed computer numerically controlled deterministic microgrinding equipment and magnetorheological finishing processes eliminate the industry's reliance on the specialized skills required to operate today's costly labor-intensive conventional manufacturing processes. These newly developed enabling technologies extend the manufacturing state-of-the-art to provide optical manufacturers with a cost effective capability to produce precision optics.
A 3-D coordinate measurement with novel concept and experimental arrangements of large space and multiple viewpoints is proposed. The measurement system includes a stereovision sensor and a separate LCD stripe projection. This measurement method ensures a high number of object points, up to 5x5x5m measurement volume, and rapid data
acquisition. If only one and next partial view have an overlap area, system could automatically transform each partial views measuring data into a same world coordinate system. It can measure a wider area or 360 degree (whole-body) shape by alter the stripe projection's position. Furthermore, it is unnecessary to stick any marker on the
object surface and a subsequent matching of the partial view is not required to obtain a whole-body measurement.
A new approach is presented to detect and track the natural features of unprepared scenes from sequential images which can be used in the outdoor AR system. Firstly, a corner detection system algorithm based on the SUSAN method find the most reliable feature points in the image of natural scene. Then, those detected points are matched in different image. Furthermore, motion parameters are calculated by
means of epipolar line constraint. Finally, motion prediction is used to minimize the searching scope in the next step. The method is tested through several images of a natural scene from a sequence of video image.
This article presents a technique, based on PC system, of skull surface triangulation representation for coronal CT images. First, the end-user selects interactively a point within the Region of Interest (ROI), and the computer will automatically position the selected ROI. The boundary points of the ROI is extracted and ordered according to their spatial orientation. Then, the boundary points between two adjacent slices are triangulated by virtual of the optical
local morphology. We briefly introduce the technique how to get the patch of skull defect in the commercial software package Surfacer. So the geometric representation using triangular patch can be produced by rapid prototyping and tooling. Finally, the experimental results show that the technique proposed is efficient for the reconstruction of broken part of skull surface and convenient to surgical repair of skull defect. Also, we have found that the technique is robust in implementation.
Crossed-optical-axes project grating system is fundamental architecture in 3-D profilometry measurement. Confined by three conditional constraints, it has some limitations in practical application. An improved system relieving the constraints was proposed here. Geometrical deduction based on image ray tracing, optical triagulation and pinhole model was carried out. By projecting another central line fringe as the zero-phase datum, wrapped phase map about reference or measured object could be unwrapped without inducing systematic errors. The simulation was to measure a plate
with a height of 80mm when changing geometrical parameters. Compared with the conventional configuration, new system approves more flexibility and maneuverability.
In the present article results of measurements of focal length of a convex lens carried out using non-interferometer methods, namely, the nodal point method and the magnification method were analysed and the uncertainties involved were estimated and compared with in both of the cases.
Optical manufacturing is very important to semiconductor, photonics and MEMS, and lithography is a core part of optical manufacturing. The development of lithography technologies, such as coating, exposure, resist and thick resist lithography, are mainly introduced.
In this paper, a novel method to analyze the crosstalk in parallel free space optical interconnects employing the VCSEL arrays and detector arrays is presented. The light emitted from the VCSEL is calculated based on the structure of laser with distributed Bragg reflectors. The channels are arranged in their position order in the point-to-point interconnects. The beam diffractive propagation induced by the nearest channels is described in the free space. The
sign to noise ratio due to the nearest to the tenth nearest channels is calculated.
A small optical correlator has been developed with shortened optical architecture and spatial folded architecture by means of design of new specified two FT lenses, which is fully controlled by Windows-based software. A hybrid real-time pattern recognition system comes into being, since it integrates the programmability, flexibility and accuracy of electronic computer to the rapidness, huge information and
parallelism of optics. The small optical correlator overcomes the disadvantages of complex structure, bulkiness and resort to optical platform. It not only possesses such good performances as small bulk, vibration strength and high discrimination, but also can easily be switched between VanderLugt and joint transform operation due to its
Compared with Vander Lugt correlator, joint transform correlator offers many advantages, such as no complex filter fabrication and stringent alignment problems, flexible structure, easy realization of correlation and suitability for real-time implementation. So in the article, the small optical correlator is used as one-armed JTC to study in two applications: license plate recognition and license plate
Two methods are used to recognize license plate in JTC. One is feature-extracted preprocess, joint power spectrum subtraction and adaptive threshold; the other is data fusion and Lagrange multiplier. Meanwhile, considering the traits of CCD and framer, the program is optimally designed to make JTC system work on line. License plate supervision can be realized by choosing correlation threshold. License plate recognition and supervision are able to be switched by a
shortcut key in C++ Builder. Computer simulation results and optical experiment results have been presented in the article
Laser radar is a distance measurement system, which makes laser range scanning and receives echo signal is order to get range images. Digital signal processors (DSPs) are based on an advanced modified Harvard architecture and a pipeline operation. TI DSPs have characteristics made them the ideal choice for a wide range of processing applications and architectures designed specifically for real-time signal processing. In this paper, range image segmentation method based on the basis operation of mathematical morphologly and
an estimation algorithm based on adaptive surface fitting and robust M-estimation is proposed. The segmentation and estimation algorithm was applied successfully to many real range images; the processing speed and noise immunity is better than traditional methods.
A noncontact system for detecting and monitoring the grain and contour of optical connector end face based on Mirau-type interferometer is proposed in this paper. In this system, phase shift technique has been adopted. A five steps algorithm is presented. By this algorithm, the computer can analyze the interference pattern and unwrapped the phase information of the detected surface. Then we can get the differential height of every point on the surface. This
method is capable of measuring fiber height to ±0.003 microns and radius of curvature and offset of polish to ±0.30 mm and ±2.0 microns respectively. So we can get not only 2-D and 3-D topography of testing surface, but also the evaluation parameters of surface roughness.
An inspection system has been developed for on-line detection of film defects, which bases on combination of photoelectric imaging and digital image processing. The system runs in high speed of maximum 60m/min. Moving film is illuminated by LED array which emits even infrared (peak wavelength λp=940nm), and infrared images are obtained with a high quality and high speed CCD camera. The
application software based on Visual C++6.0 under Windows processes images in real time by means of such algorithms as median filter, edge detection and projection, etc. The system is made up of four modules, which are introduced in detail in the paper. On-line experiment results shows that the inspection system can recognize
defects precisely in high speed and run reliably in practical application.
In this paper, an auto-focusing system based on Signal Processing of Single-chip Microprocessor is introduced to realize auto-focusing. The system can automatically get the distance information of the worktable and drive the step motor to reach the aim of auto-focusing.
The auto-focusing system is loaded in the original CMOS-based measuring system. After the AV signals from CMOS image sensor pass through the analog filter, the single-chip microprocessor samples and processes them, then controls the lens to be in focus. As a result, this method can not only achieve all functions of focusing, but also avoid complicated calculations. The system is low power consuming,
programming rapidly. Here we analyse the key technique of the system and the results of the experiments are given. It can be practical applied and the further perfection of algorithm and software will result in the system having more function.
A new method for calibrating stereo photogrammetric system is presented. The relative position of the two cameras are determined from epipolar constraint and computed through linear normalization eight-point algorithm and M-estimator method. Calibration is carried out by moving a scale bar, which has six small infrared LED marks and the distances between these marks are used to determine the scale factor and the cross ratio invariant of the two distances between
the three marks on rigid reference bar is used to verify the matching quality. Due to take infrared LED as feature point and the light intensity of these feature points can be automatically controlled according to the distance between cameras and reference bar, the imaging feature points have uniform intensity profile and high contrast with background, and hence the calibration accuracy is improved. The simulations and experimentations have shown that the
calibration accuracy can be compared with complex off-line calibration.
An optical probe imaging based, fully automatic and rather flexible stereo vision system for 3D coordinate on-line measurement is presented and analyzed. In this system, the relative position of the two cameras can easily be calibrated by observing an optical reference bar in different locations and orientations through the measurement according to epipolar constraint and the certified distance of the features on the reference bar. For measurement, the
system takes an optical probe, which has one reference mark and five optical feature points, as imaging target, and makes use of the measurement results of these feature points space coordinates to calculate the measured object point coordinate which contacts with probe tip. To improve the calibration and measurement accuracy, the system takes infrared LED as optical feature point, and optimized signal to noise ratio by automatic LED light intensity, located
these feature imaging points by bilinear centroid sub-pixel algorithm. The effectiveness of the proposed system has been test by experiments.
In this paper, an apparatus has been designed to inspect the end surface of fiber optic connectors. A white-light high-brightness light emitting diode has been adopted to offer enough light power. Zoom lenses comprise field lens and achromatic lens with a large range of magnification from 1.25 to 60. They can be used to inspect not only the whole ferrule but also the details of the core. The illumination system has two modes: perpendicular and oblique. In oblique illumination, the relation on the maximum length of shadow
along the incident direction and the angle of oblique illumination is disclosed and the curvature of shadow is drawn. Fiber undercut and protrusion can be judged whether they are satisfied the tolerance with the curvature.
Erbium-doped fiber is a main component of Erbium Doped Fiber Amplifiers (EDFAs), which is wildly used in optical communication. Erbium doped fiber is a good sensing material of fluorescence temperature sensors as well. The Erbium-doped-fiber temperature sensors can operate under high temperature up to 1100°C.
Fluorescence sensors show considerable promise, with the advantage of being intensity independent. Following the termination of a square excitation light pulse, the fluorescence signal is an exponential decay, which decay lifetime depends on the temperature and can be measured by several methods. The decay acquisition and estimation
methods are one kind of them. Different arithmetic is developed such as the Marquardt method, the Prony method and the log-fit method.
A new estimation is given in this paper, basing on the FFT (Fast Fourier Transform) and the Taylor series. The fluorescence lifetime can be calculated from the items of the FFT with different accuracy. This method is especially designed for the long-fluorescence-lifetime system, for example, Erbium-doped fiber sensing with lifetime up to
10mn. However this method can be used for other fluorescence material also with a little shift. The advantages of this method include high accuracy, quick processing, independence on the base offset etc.
The effect of this method is discussed and compared with other estimation methods by numerical simulation and experiment results.
A method of fabricating an off-axis, lightweighting aspheric mirror is described, and its final results is given. The rectangle aperture of the mirror is 590mmx210mm, and its lightweighting rate is 50%. The final accuracy reached up to λ/40 RMS where λ equals to 632.8nm.