Light projection method is often used in measuring system for wire diameter, which is relatively simpler structure and lower cost, and the measuring accuracy is limited by the pixel size of CCD. Using a CCD with small pixel size can improve the measuring accuracy, but will increase the cost and difficulty of making. In this paper, through the comparative analysis of a variety of sub-pixel edge detection algorithms, polynomial fitting method is applied for data processing in measuring system for wire diameter, to improve the measuring accuracy and enhance the ability of anti-noise. In the design of system structure, light projection method with orthogonal structure is used for the detection optical part, which can effectively reduce the error caused by line jitter in the measuring process. For the electrical part, ARM Cortex-M4 microprocessor is used as the core of the circuit module, which can not only drive double channel linear CCD but also complete the sampling, processing and storage of the CCD video signal. In addition, ARM microprocessor can complete the high speed operation of the whole measuring system for wire diameter in the case of no additional chip. The experimental results show that sub-pixel edge detection algorithm based on polynomial fitting can make up for the lack of single pixel size and improve the precision of measuring system for wire diameter significantly, without increasing hardware complexity of the entire system.
Utilization of the spectrum simulation in many important fields widely, it has made the target spectral simulation technique to be an important development trends. With the rapid development of the application of the LED technology, the LED have the merits of long serving life, high lighting efficiency, rapid responding time, and high wide selection of light band. Consequently, taking the demands of designing for the target spectral scene reproduction systems into consideration, LED with variable light bands as the light source, and performs Gauss Curve calculation to fit spectra in scene via Matlab software, and therefore serving as the criteria to selection of LED. Meanwhile, the system of driving a light source applies high performance embedded MCU as the main data processor. The chip for LED is a specific driver chip which was made in TI Corporation. Through analyzing the data collected from the target spectra in scene, then the processor transfers the calculated results to the driver IC (integrated circuit) of LED. The spectrum in scene is reproduced basing on the results. Moreover, this design method can also combine with spectrometer directly to realize the real-time capability of reproduction of the spectra in scene. It has a great potential application in the future.
A new design scheme has been proposed that aim to realize real time, on line raw silk diameter
measurement based on linear CCD (Charge Coupled Device) and FPGA (Field Programmable Gate
Array).In this system, the samples of raw silk are placed in parallel light which reflect light through macro
imaging is received by CCD image sensor. The research on how to improve precision of the system from
theoretical approach to various functional modules parameter optimization. What’s more, effects are solved
in instability of light illumination and raw silk transparency, linear CCD's dark background imaging is
chosen to avoid bright background image easily saturation, distortion caused by raw silk jitter is eliminated.
system measurement accuracy reaches to±1μm,experimental results prove that research programme has
certain feasibility and practicality.
The task of an area CCD camera on a satellite is imaging to the earth or space targets. The variety of theirs motion
relative speed between a CCD camera and a target should cause some ambiguity of the picture obtained, final the visual
result of a picture (imaging quality) goes to the bad. For the above this paper should introduce the simulation by a
computer and the experimentation to a motion platform in the lab, the theoretical simulation and experimental results are
compared, the analysis to the image quality is about the speed and the exposure time of an area CCD camera in orbit, the
empirical data has been obtained by the moving between the pixels of an area CCD camera and a target during exposed.
The paper presents a method for the optical storage based on the principle of grating diffraction .The information coding
system has included these contents, such as the encoding information, constructing a tow array of grating cells and
coding them. The information coding into an array is called the Star-Array Code, because those information as like the
flashing stars in the sky sometimes bright or sometimes dark. These information are encoded a group of grating cells
with the various space frequency. In the array these grating cells are formed orthogonally each other. There are two
methods for designing the encoding, and discuss the foreground of the Star-Array Code is applied.
Proc. SPIE. 7284, 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems
KEYWORDS: Digital signal processing, Imaging systems, Lenses, Image processing, CCD cameras, Micromirrors, High dynamic range imaging, Image enhancement, Charge-coupled devices, Digital micromirror devices
DMD used as SLM modulation area array CCD design is proposed in the paper. It can Solve a problem in exposing
high-contrast scenes by ordinary CCD camera, with images appearing over-exposure or under exposure, bringing a loss
of the details of the photo. The method adoptes a forecast imaging scene, CCD is purposely designed by way of
more exposure regions and exposure times. Through modulation function of DMD micro-mirror, CCD is exposed with
sub-region and time-sharing, at the same time a purposely designed structure of image data enhances the area CCD
dynamic range. Experiments shows: This method not only improves visible quality of an image and clear details in the
backlighting or highlight, but also enhances the dynamic range of image data. The high-quality image and high dynamic
range data are real-time captured, the "fused" software is no longer required.
Thermal environment adaptability is an important aspect which should be involved in the development and test of a
space camera. Generally, vacuum thermal test and thermal cycle test are two important thermal tests to ensure the
reliability of a space camera. In this paper, vacuum thermal test and thermal cycle test of a space camera are introduced.
During the test, we check if the camera can work normally and evaluate performance of the camera under different
temperature. The performance is evaluated by the modulation transfer function (MTF) of the camera. According to the
measured MTF curve, the influence of temperature on performance of this camera is evaluated.
Proc. SPIE. 7156, 2008 International Conference on Optical Instruments and Technology: Optical Systems and Optoelectronic Instruments
KEYWORDS: Signal to noise ratio, Clocks, Image segmentation, Image processing, Field programmable gate arrays, CCD cameras, Signal processing, Charge-coupled devices, CCD image sensors, Camera shutters
Frame transfer charge-coupled device (CCD) sensors have several characteristics which are suitable for spectroscopic
analysis, scientific imaging, industrial measurement and so on. A simple platform for frame transfer CCD has been
developed in this paper. The platform can implement variable integral time and pixel binning which can dynamically
alter the "grain size" of frame transfer CCD and correspondingly alter the "photographic speed" of the device. With the
fixed optical system and pixel size, integral time changing and pixel binning can allow adjusting the dynamic range to
suit the source intensity. The integral time Elongation can detect the low intensity of the scene but depress the
recognition of the moving objects. Pixel binning can intensify the capability of charge collection and further reduce CCD
Readout noise. The platform we design can satisfy the complex and precise time sequences of CCD driving and process
sequences, including CCD driving clocks, electronic shutter signal, A/D and black pixels clamp clocks and double
correlation sampling clocks, pixel binning signal and so on. Images with various pixel binning and integral time have
been acquired by using this platform on the CCD circuit system board which has been designed by our team.
Based on a DMD spatial light modulator, a scheme for enhancement of the dynamic range of FPA
detector is put forward. High dynamic range images are captured through local multiple exposures to a
high contrast scene. When such a scene is taken with conventional cameras, it is hard to obtain a
satisfying picture since the high and low luminance areas are respectively over and under exposed. A
direct method to solve the problem is to use a FPA detector with high dynamic range. Such kinds of
FPA detector are rising up but still expensive now. An alternative is to acquire multi images of same
scene with different exposure times and to fuse them through processing program. It is unsuitable for
the case where there are moving targets in scenes. Even for a static scene, it can take long time to
obtain an image with high quality. The method suggested in this paper has the advantage that a high
dynamic range image can be obtained through a single exposure. According to the image acquired by
pre-exposure to the scene, many segments and their corresponding exposure times are determined. And
through control of the switch time of micro-mirrors in the DMD, a high dynamic range image with
high image quality can be acquired by single integration of FPA as a CCD or CMOS sensor.
Frame transfer area-array CCD camera is the perfect solution for high-end real-time medical, scientific and industrial
applications because it has characteristics of high fill factor, low dark current, high resolving power, high sensitivity,
high linear dynamic range and electronic shutter capability. Time sequences of frame transfer area-array CCD camera
have two compact segments: CCD driving sequences and CCD signal processing sequences. Proper working of CCD
sensor lies on good driving sequences while accurate CCD signal processing sequences ensures high quality of CCD
image. The relationship among CCD camera time sequences is complex and precise. The conventional methods are
uneasy to implement time sequences of Frame transfer area-array CCD. Embedded designing method is introduced in
this paper and field programmable gate array device is chosen as the hardware design platform. Phase-locked loops are
used for precise phase shifting and embedded logic analyzer for waveform verification. CCD driving clocks, electronic
shutter signal, A/D and black pixels clamp clocks and double correlation sampling clocks have been attained on the
hardware platform and this timing generator can control exposure time flexibly. High quality images have been acquired
through using this timing generator on the CCD circuit system board which has been designed by our team.
The remote camera developed by us is the exclusive functional load of the micro-satellite. The
remote camera is based on the frame transfer CCD sensor DALSA FT18, and for the purpose of
insuring system reliability, the development of the remote camera indispensably simplifies the design
of mechanical and electrical shutter, which causes the problem of CCD smearing in remote sensors, and
leads to the distortion of remote sensing images. In this paper we present a reversely stepwise method
to solve the CCD smearing problem in remote sensors. The images retrieved from data after correction
show great improvement in image contrast and quality.
Micro-satellite is characterized by miniaturized structure and low cost, so it is a good choice to use area array CCD space
camera as image system on micro-satellite. FT-18 is a monochrome frame transfer image sensor offering 1024×1024
pixels with excellent antiblooming and variable electronic shuttering. The main components of driving circuit for FT-18
include power supply unit, microcontroller unit, clock signal generator unit, and analog-to-digital (A/D) converter. The
microcontroller unit controls startup sequence of all voltage, the exposure time of CCD and the working status of A/D
converter; the clock signal generator unit generates sequence signals for CCD and A/D converter; the A/D converter
converts the output of FT-18 to a 12-bit digital output. Special attention should be paid to the reliability of this camera for
it will work in a condition different from ground. The camera may suffer from vacuum discharge, particle radiation,
strong shock, hypergravity and so on. All these should be considered in the design of space camera, and enough
environment tests should be done to ensure it can work normally in space.
Diffractive composite spatial code is a novel concealed optical code. It use diffractive micro-gratings matrix as carrier of diffractive composite spatial code. When diffractive micro-gratings matrix is lighted with monochromatic plane wave, diffractive composite spatial code appears. With the aid of specific recognizer, meanings which diffractive composite spatial code represents will be read out. Coding principle and design ofdiffractive composite spatial code are introduced in details in this paper. Detecting technology of this code is explored, too. The analyzing indicates that the method of recognizing of diffractive composite spatial code is unsophisticated and feasible. These characteristics are very important and useful in security of document, bond and even web.