Linear Array Image Sensor Research Articles

Stain-Detection and Anti-Stain Algorithms Based on Dual Detector Data Interchange in Image-Type Displacement Measurement Technology

Displacement measurement technology based on image recognition algorithms represents a novel high-performance technique. In such measurements, when there are stains contaminating the measuring light path, it causes recognition errors from the linear array image sensor on the grating, resulting in inaccurate measurement results. Therefore, this report proposes stain-detection and anti-stain algorithms based on image recognition. The principle of image-type displacement measurement technology is described, and the influence of stains on the displacement measurements is analyzed according to four criteria in order to judge whether there are stains present. Then, an anti-stain algorithm based on the data exchange of dual-image sensors is proposed. Finally, experimental verifications are carried out. The experimental results show that the proposed algorithm effectively identifies the errors in the displacement measurements, when the experimental device is contaminated, the developed algorithms can accurately self-correct for the stain’s interference. The results presented herein provide a theoretical basis for developing highly-reliable displacement measurement devices.

Vision-based system for simultaneous monitoring of shaft rotational speed and axial vibration using non-projection composite fringe pattern

Abstract Both the instantaneous rotational speed (IRS) and vibration of a rotating shaft are key information for condition monitoring and faults diagnosis of rotary machinery. Instead of using a rotational speed encoder and a displacement sensor to measure the IRS and the vibration of a rotating shaft, a non-projection fringe pattern and vision-based system was proposed to realize simultaneous measurement of IRS and axial vibration of a rotation shaft. A composite fringe pattern (CFP) was pasted around the surface of the shaft and worked as IRS and displacement sensors. Each line fringe intensity along the axial direction contained two fringe period densities (FPDs), in which each FPD ratio only corresponds to a rotational angle. A linear array image sensor was employed to record the fringe intensity, from which the time domain rotational angle could be obtained from the change of the FPD ratio and the axial displacement could be acquired by locating the maximum peaks of the cross correlation between the recorded fringe intensity and the reference one. Thus, the IRS could be obtained accurately and efficiently from the rotational angle by multiplying the sampling frame rate of the high-speed camera. Simulated and experimental results demonstrated that the proposed system could simultaneously extract the IRS and axial displacement with the advantage of non-contact and effectiveness. Therefore, the proposed system provides an alternative vision-based approach for the simultaneous measurement of IRS and axial vibration.

The application research on improvement of genetic algorithm in linear CCD detection

When the linear array image sensor (CCD) is used for spot detection, the optimization of the detection signal is usually one of the problems that plague the user. In linear array imaging sensor (CCD) detection applications, optimization of the detection signal is usually one of the problems with the user. Based on the characteristics of linear array CCD detection signal, a genetic algorithm (GA) is established to solve the problem of mathematical model. In this paper, a new adaptive genetic algorithm (IGA) with directional adaptive guidance and adaptive control technology and threshold constraint technology are proposed for the lack of local optimization ability of the standard genetic algorithm (SGA), premature convergence and low accuracy. By applying IGA to the actual detection data, it is proved that IGA has certain advantages in solving the problem of linear CCD detection signal optimization. In the end of this paper, the performance of IGA, SGA and peak finding algorithm (SP) are analyzed and compared, which fully demonstrates the advantages of IGA in solving such problems.

Instantaneous measurement system of the effective photon energy for a single shot x-ray pulse radiation

For a short pulse x-ray radiation with extremely broad spectrum such as Bremsstrahlung, the effective photon energy cannot be determined by conventional x-ray detectors with only a single x-ray pulse shot. An instantaneous measurement system capable of determining the energy with a single shot has been developed. The system is made of a metal–oxide–semiconductor linear array image sensor, a scintillation phospher, and an absorber material, and a control system of the sensor. The energy of a hard x-ray pulse with a short pulse duration of 500 ns is determined with this system. It is shown that the system can determine the energy more quickly and accurately than with the conventional method.

O-22-329 - Intraoperative measurement of tumor and peripheral cerebral blood flow with laser-Doppler flowmetry

Both the instantaneous rotational speed (IRS) and vibration of a rotating shaft are key information for condition monitoring and faults diagnosis of rotary machinery. Instead of using a rotational speed encoder and a displacement sensor to measure the IRS and the vibration of a rotating shaft, a non-projection fringe pattern and vision-based system was proposed to realize simultaneous measurement of IRS and axial vibration of a rotation shaft. A composite fringe pattern (CFP) was pasted around the surface of the shaft and worked as IRS and displacement sensors. Each line fringe intensity along the axial direction contained two fringe period densities (FPDs), in which each FPD ratio only corresponds to a rotational angle. A linear array image sensor was employed to record the fringe intensity, from which the time domain rotational angle could be obtained from the change of the FPD ratio and the axial displacement could be acquired by locating the maximum peaks of the cross correlation between the recorded fringe intensity and the reference one. Thus, the IRS could be obtained accurately and efficiently from the rotational angle by multiplying the sampling frame rate of the high-speed camera. Simulated and experimental results demonstrated that the proposed system could simultaneously extract the IRS and axial displacement with the advantage of non-contact and effectiveness. Therefore, the proposed system provides an alternative vision-based approach for the simultaneous measurement of IRS and axial vibration.

Design of an in-water spectrograph for irradiance measurements in the ocean

A low focal ratio ( f /l.8) visible range (350 nm to 750 nm) spectrograph containing an aberration-corrected concave holographic grating and a 512-channel linear array image sensor has been designed for use in an in-water spectroradiometer. A ray-trace analysis using different input wavelengths has been made, so as to optimize and assess the optics. The design analysis also includes calculations on the expected resolution, system etendue, and the simulated response of the complete system to a known in-water spectrum. The modular design concept of the spectrograph can be exploited by using it as a basic building block for other spectral measurements in the ocean.

CoSTEL: a computer peripheral remote sensing device for 3-dimensional monitoring of human motion.

An automatic system (CoSTEL) which permits the reconstruction of the instantaneous 3-dimensional position of target points (infra-red light emitting body markers) in a laboratory frame was designed. The 3-dimensional CoSTEL transducer is based on a suitable spatial arrangement of three one-dimensional transducers. Each transducer is made of a charge-coupled device linear array image sensor lying on the focal plane of a toroidal lens and appropriately aligned with it. The system was conceived for 3-dimensional whole body movement analysis and is able to track eight landmarks per subject side simultaneously. Its basic features are resolution of 1/4000, maximum sampling frequency 1·1 kHz (100 Hz is actually used), large insensitivity to background light and transducer output in digital form. These features provide a high level of accuracy, reliability and working stability.

Computer controlled image sensor and its application

The rotation and data extraction of a linear array image sensor is controlled by a minicomputer, so that the desired information about the optical field at the face of the sensor can be extracted effectively. To obtain operations for the data, three kinds of averagings are adopted, that is, (1) simple averaging of intensity fluctuation at each sampling point, (2) second-order cross-correlation of fluctuations of intensities at two different sampling points, and (3) triple correlation of intensity fluctuations at three different sampling points. They are used (a) for the derivation of images averaged over any desired time interval, (b) for the measurement of the modulus of coherence function, and (c) for the measurement of a complex coherence function by an intensity triple correlator aiming at the imaging of incoherent objects with general shapes and measuring the statistical characteristics of the turbulence. Typically the characteristics of the system are: (1) observation area: over a disk of 8-mm diam; (2) spatial sampling interval: 50 microm; (3) temporal sampling interval: 500 microsec; (4) coherence function over the observation area is derived within 5 min and stored in a minicomputer, (5) by applying the Fourier transform to the observed coherence function the image or coherence function of the object is obtained in 2 min and is also displayed as the output of the minicomputer. The reconstructed images of incoherent objects show the usefulness of the device.