Based on local features, a new adaptive classification approach for multispectral remote sensing data is presented. Typical classification techniques based on global features tend to degrade because all classes are projected along the same direction, e.g. the principal component direction for Principal Component Analysis (PCA) and minimum component direction for Minimum Component Analysis (MCA). The typical methods are under the assumption that class separability is uniform for all directions, which is not always true. The new method overcomes that disadvantage by selecting features, which give the maximum class separability, based on local information of the classes instead of global information. In the new method, a projection matrix for every class is first sought based on making its training examples well separated from the others. Every input vector is then linearly transformed into another space by every projection matrix. In the transformed spaces, it can be classified or labeled to different class by Maximum Likelihood Classification (MLC). In order to reduce computation cost, adaptive dimension reduction is also introduced. Good performance of the new method can be shown from the experimental results on the Kennedy Space Center (KSC) TM images.
In modern semiconductor and optics industries, there is a strong demand for a highly sensitive and non-contact surface profilometer. This paper describes an optical heterodyne surface profiling interferometer for on-line non-contact measurement with automatic focusing which has been developed recently. The essential feature of the profilometer is a newly designed common-path configuration to minimizes the effects caused by vibration, air turbulence and other environmental variations. A single-mode frequency-stabilized laser diode (780 nm) serves as the light source to make the whole system compact (total volume 250L x 200W x 100Dmm). A powerful signal processing scheme is also developed, which includes three parts: automatic voltage control, phase measurement and automatic focusing control. All these make the repeatability and stability of the profiling interferometer greatly improved. The system has vertical resolution of 0.39 nm and lateral resolution of 0.73 micrometer. During approximate an hour, the stability is within 1.95 nm (3σ).
A common-path heterodyne interferometer for on-line non- contact measurement of surface profile has been developed. A single-mode frequency-stabilized laser diode (780 nm) serves as the light source to make whole system compact (total volume 250L X 200W X 100Dmm). The optical common-path configuration remarkably minimizes the effects caused by vibration, air turbulence and other environmental variations. Multiperiodical phase measuring technique, which is based on the combination of fractional periodic phase measurement and integer periodic phase counting, is employed in signal processing, so the system features not only high vertical resolution but wide measuring range as well. In addition, the automatic focusing system greatly facilitates the measurement especially on-line profiling. This paper gives the brief principles, the arrangement of the interferometer and some test results. The system has vertical resolution of 0.39 nm and lateral resolution of 0.73 micrometer. The stability is 1.95 nm (3(sigma) ) during about 1 hour and the accuracy of automatic focusing system is 0.1 micrometer within plus or minus 25 micrometer of the focus.
In this paper, design of the OAH-M7 Optical RAID system is discussed. Scatter/Gather method is used in data stripping and data reconstruction to improve the data transfer rate. In addition, the function of each model is described.
This paper describes the probabilities of concurrent access to an optical jukebox in a hierarchical VOD system, it also explains some fundamental principles for the retrieval and storage of video data. Using a simplified general framework, both singled and multiple video streams playback are discussed. As a result, there are three ways to support more users to access an optical jukebox directly.
In modern semiconductor and optics industries, there is a strong demand for a highly sensitive and non-contact surface profilometer. This paper describes an optical heterodyne surface profiling interferometer with automatic focusing which has been developed recently. The essential feature of the profilometer is a newly designed common-path method to minimize the effects of environmental conditions. A powerful signal processing scheme is also developed, which includes three parts: automatic voltage control, phase measurement and automatic focusing control. All these make the repeatability and stability of the profiling interferometer greatly improved. The height resolution is 3.5 nm and lateral resolution is 0.4 micrometers . Experiments show that the profiling interferometer is suitable for on-line use.
Proc. SPIE. 3000, Laser Diode and LED Applications III
KEYWORDS: Signal to noise ratio, Optical fibers, Avalanche photodetectors, Optical amplifiers, Semiconductor lasers, Time metrology, Temperature sensors, Spatial resolution, Prototyping, Temperature metrology
The paper presents theoretical and experimental investigations on distributed anti-Stokes ratio thermometry (DART) sensing for monitoring temperature in complicated structure. A technique, based on maximizing signal to noise ratio (SNR) of DART, has been proposed. A preliminary prototype DART system based on a microcomputer has been developed and optimized by this technique. It has spatial resolution of 15.6 m (limited by pulse width of the laser), measuring time of 160 s, temperature resolution of 7 degrees Celsius, sensing upper limit of 260 degrees Celsius, and sensing distance of 1.5 km.
The paper presents an analysis of the signal to noise ratio of distributed anti-Stokes ratio thermometry (DART) to quantify the effect of varying the gain of the avalanche photodiode (APD). An optimal gain is found based on maximizing the signal to noise ratio of the received circuit output. Good agreement between calculated and measured avalanche gain of APD is obtained.
An improved signal processing method for laser interferometer is investigated to measure the radius of large precision centrifuge. Based on phase and integer periodic phase measurement, it not only makes the resolution up to 1 in 2000 of a wavelength, but also enlarges the range of the interferometer. The absolute radius measurement of the 5m centrifuge with the accuracy of +/- 3.4micrometers is achieved.
On the basis of the combination of phase measurement and integer periodic phase measurement, a signal processing
scheme, which is used for optical heterodyne interferometer with large range, is described. It not only maintains the
high measuring resolution , but also enlarges the measuring range, with solving the problem of large range and
measurement of dynamic displacement.
A new method for restoring turbulence-degraded images is proposed. It is based on the turbulence-degraded model. The parameter in the model is sought automatically to determine the actual point spread function (PSF) of the turbulent atmosphere, therefore the degraded images are retrieved by traditional techniques. The method needs no information about the turbulence. Experimental results verifies the effectiveness of the method.
Two methods are described in this paper: the first one, which is based on the strict constraints of the structure function of atmospheric turbulence, is used to generate random wavefronts; the other method is used to measure the atmosphere correlation length from the long-exposure degraded image. Simulation results verify the effectiveness of the two methods.