Có 16+ tài liệu thuộc chủ đề "kỹ thuật quang học"
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Nội suy ảnh sử dụng các ràng buộc hình học. Trình bày cơ sở lý luận về phương pháp nội suy: nội suy tuyến tính, nội suy song tuyến tính, nội suy spline và nội suy ảnh theo hướng. Phương pháp nội suy;. Xử lý ảnh. Là học viên cao học đã được học một số môn liên quan và...
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CƠ CHẾ HÌNH THÀNH BỒ HÓNG TRONG QUÁ TRÌNH CHÁY CỦA ĐỘNG CƠ DIESEL. Bồ hóng là chất ô nhiễm đặc biệt quan trọng trong khí xả động cơ Diesel. Sự nguy hiểm của bồ hóng đối với sức khỏe con người đã được đề cập đến ở chương 1. Các HAP, kể cả các nitro-HAP và dinitro-HAP hấp thụ...
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Figure 1.1 shows a snapshot of a harmonic wave that propagates in the z-direction. The argument of the cosine function is termed the phase and δ the phase constant. ν = the frequency (the number of waves per unit time) k = 2π/λ the wave number. The relation between the frequency and the wavelength is given by. Figure 1.1 Harmonic...
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In this chapter we develop the relations governing the passage of light rays through imaging elements on the basis of the paraxial approximation using matrix algebra. Finally we go through some of the standard imaging systems.. Consider Figure 2.1 where we have a sphere of radius R centred at C and with refractive index n . The ray is incident...
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Because of the slow response of practical detectors, interference phenomena are also a matter of averaging over time and space. In recent years, lack of coherence has been taken to advantage in a technique called low-coherence or white-light interferometry, which we will investigate at the end of the chapter.. As can be seen, the resulting intensity does not become merely...
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This must be due to a bending of the light around the edge of S 1 . If this hole is made small enough, the light will not propagate as a narrow beam but as a spherical wave from the centre of the hole (see Figure 4.2). This simple principle has proved to be very fruitful and constitutes the foundation...
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Because of the increasing use of the CCD camera in optical metrology, this device is described separately in Section 5.8.. Radiant flux density at a surface, M = E = ∂/∂A, is the radiant flux at a surface divided by the area of the surface. Figure 5.1 The concept of radiance. 2 /∂∂A cos θ Luminance lm sr −1 m...
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Although holography requires coherent light, it was invented by Gabor back in 1948, more than a decade before the invention of the laser. Because of the above-mentioned properties, we shall see that holographic interferometry has many advantages compared to standard interferometry.. One of the partial waves is directed onto the object by a mirror and spread to illuminate the whole...
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Figure 3.2 is an illustration of two interfering plane waves. This is an example of the moir´e effect and the resulting fringes are called moir´e fringes or a moir´e pattern. Figures 3.4, 3.8 and 3.9 are examples of the same effect. Today there is little left of the moir´e effect, but techniques applying gratings and other type of fringes are...
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In the years following the advent of the laser, this pattern was considered a mere nuisance, especially in holography (and it still is. In this chapter the basic principles of the different techniques of speckle metrology will be described. This white-light speckle photography is included in the final section of the chapter.. In Figure 8.1, light is incident on, and...
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Unequal polarization of the interfering waves results in a bias intensity which reduces the contrast of the fringes and, in the limit of opposite polarization, we get no fringes at all. In analysing finer diffraction effects, the vector property of the light must be taken into account, for example in the reconstruction of a hologram (G˚asvik 1976). By including the...
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10.1 INTRODUCTION. 10.2 THE FRAME GRABBER. Figure 10.1 Block diagram of frame grabber. The pixel clock in the frame grabber defines the sampling interval of the A/D converter and generates an internal Hsync signal. 10.3 DIGITAL IMAGE REPRESENTATION. 10.4 CAMERA CALIBRATION. Figure 10.2 Digital image representation. 10.4.1 Lens Distortion. x i = mx o (10.1a). y i = my o...
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11.1 INTRODUCTION. In Sections and 11.5, techniques for continuous determination of the phase of the fringe function are described. 11.2 INTENSITY-BASED ANALYSIS METHODS 11.2.1 Introduction. 11.2.2 Prior Knowledge. As shown in Figure 11.2 the flaw sites are marked with small crosses.. 11.2.3 Fringe Tracking and Thinning. Figure 11.1 Procedure for the analysis of Figure 11.2 (From Robinson, D. With respect...
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12.1 INTRODUCTION. Electronic cameras (vidicons) were first used as a recording medium in holography at the beginning of the 1970s. At the beginning of the 1990s, computerized ‘reconstruction’ of the object wave was first demonstrated. This is, however, not a reconstruction in the ordinary sense, but it has proven possible to calculate and display the reconstructed field in any plane...
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13.1 INTRODUCTION. 13.2 LIGHT PROPAGATION THROUGH OPTICAL FIBRES. Figure 13.1 shows the basic construction of an optical fibre. n 0 sin θ 0 = n 1 sin θ 1 (13.1) where n 0 is the refractive index of the surrounding medium. Figure 13.1 Basic construction of an optical fibre. which combined with Equations (13.1) and (13.2) gives. N A =...