It is very important to measure the vibration amplitude and the dynamic deformation of the object
so Electrical Speckle Pattern Interferometry technique has developed rapidly in recent years because of
its Non Destructive Testing (NDT) methodology. A dynamic Electrical Speckle Pattern Interferometry
technique was described in the paper. The Spatial Phase-shift System was implemented through four
CCD cameras. The object light interferes with the given phase shifting value of reference light at the
baget of each CCD camera. The vibration amplitude and the dynamic deformation can be measured by
the phase detecting method. The error of the influence of the disturbance of the air, the influence of the
changing temperature, and the influence of the vibration of the environment can be eliminated. The
image matching and image emendation technology were used for the images of four CCDs to optimize
the result of the measurement. The Space Phase-shift System was promoted by the transient vibration
and dynamic deformation system.
The overhead contact system is the power supply unit of the electric locomotive. This article is to introduce our newly
developed method to measure the height and pull out value of the contact wire. A carema dolly which can move on
railway is applied to bear the weight of the measure equipment; two linear CCD cameras are installed on the dolly
symmetrically about the midline of two rails. While the dolly move along the railway, two CCD cameras grasp the image
synchronously, and a computer real-time process the images, the height and pull out value can be calculate out from the
images.
In order to acquire sequence images in PIV measurement system of continuous clashing flow of water, two laser flashers,
the red one and the green one, are used in PIV measurement system. After the digital camera is triggered, the two
flashers flash in a short interval during the exposure period. The red light and the green light illuminate the same region
so that the image records the movements of tracing particles in two colors. Using digital image process technology, two
images, the red one and the green one, can be obtained from the original image. Based on the two images, the flow field
parameters can be calculated. The method possesses predominant advantages: high speed field can be measured using an
ordinary camera and the two images have determinate time labels, so the moving direction of the particles can be
determined easily. The main steps of the method include the transition from Bayer matrix to RGB matrix, the
pretreatment of the images, the analyzation of the velocity and the arrangement of the results.
Research of Non Destructive Testing (NDT) methodology has developed rapidly in recent years[1][2]. But it is rarely used
for small objects such as Micro-electronic Mechanics System. Due to the small size of the MEMS, the traditional method
of contact measurement seriously affects the parameter of the object measured. So a high accuracy non-contact
measurement is required for optimization of MEMS designs and improvement of its reliability[3][4]. With recent advances
in photonics, electronics, and computer technology, a Non Destructive Testing (NDT) laser time average interferometry
is proposed in the paper. Laser interferometry has the advantages of non-contact, high accuracy, full-field and fast speed,
so it can be used to detect cracks in MEMS. A time average measurement method of digital speckle pattern
interferometry is proposed to measure the vibration mode of the MEMS in the paper. According to the sudden change of
amplitude of vibration mode, a crack can be measured. With the speckle average technology, high accuracy phase-shift,
continuous phase scanning technology, combined with optical amplification technology, the resolution of the amplitude
reaches 1nm, and the resolution of the crack reaches 5μm. The measurement system being full-field, the measuring speed
of the measurement system can reach 512*512 points per one minute.
This article is to introduce a newly developed method to measure three-dimensional displacement by only a single
camera. To measure the 3-D displacement of the two objects A and B, two lighting diodes are fixed on object A. A
convex and a translucent screen are fixed on object B, a CCD camera is joined together with the screen. The lighting
diodes project two faculae on the screen throgh the lens. The position of the faculae can be detected by the CCD camera.
The 3-D displacement of A and B can be calculated according to the position of faculae.
KEYWORDS: Speckle, Vibrometry, Phase shifts, Calibration, Signal to noise ratio, Ultrasonics, Bessel functions, Optical calibration, Charge-coupled devices, Digital signal processing
A time-average DSPI method for nanometer vibration mode measurement is presented in this paper. The phase continuous scan technique is combined with the Bessel fringe-shifting technique to quantitatively analyze the vibration mode by time-average DSPI is used in measurement system. Through the phase continuous scan, the background and speckle items are completely eliminated, which improves the fringe quality and enhances the signal-to-noise ratio of interferogram. There is no need to calibrate the optical phase-shifter exactly in this method. The anti-disturbance capability of this method is higher than that of the phase-stepping technique, so it is robust and easy to be used. In the vibration measurement system, the speckle average technology is used, so the high quality measuring results are obtained.
A new error-correcting algorithm of phase unwrapping is proposed in this paper. This method can eliminate the propagation of phase errors in the unwrapped phase map. It is simple, effective, and has been successfully used in the deformation measurement and the quantitative analysis of vibration mode by DSPI.
The phase continuous scan technique is combined with the Bessel fringe-shifting technique to quantitatively analyze the vibration mode by time-averaging DSPI. Through the phase continuous scan, the background and speckle items are completely eliminated, which improves the fringe quality and enhances the signal-to-noise ratio of interferogram. There is no need to calibrate the optical phase-shifter exactly in this method. The anti-disturbance capability of this method is higher than that of the phase-stepping technique, so it is robust and easy to be used.
The theory, design, and characteristics of a Phase-locked Electronic Speckle Pattern Interferometry (ESPI) are described. The main principle of the Phase-lock system is to use the characteristics of spatial frequency of the object light to get the information of the phase of the objects' vibration and the disturbance of air. By using the information, we eliminate not only the influence of the objects' vibration, but also the influence of the disturbance of the air. So we can get more stable image of ESPI, and more reliable measurement result.
In this paper, we describe a 2D color grating image system. Using digital image process technology, we get the information of every pixel of a color image, then, according to the relation of pixels and grating pattern, under the control of a computer, using laser light, we make tiny oriented diffraction grating on a recording plate. The result is brilliant kinetic image which is dazzling under any light source.
A controlled-frequency-spectrum-transformation single-shot phase- sensitive autocorrelation technique is described, which enables for the first time the complete characterization of the intensity and phase of arbitrary ultrashort optical pulses by using second-order- autocorrelation.
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