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Introduction to Adaptive Lenses by Shin-Tson Wu, Hongwen Ren

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Chapter 1

Optical Lens

1.1 Introduction

Light carries information from the world to our eyes and brains. Therefore, we can see colors and shapes of the objects. It has been verified that light is a kind of electromagnetic radiation. The electromagnetic radiation is generated by the oscillation or acceleration of electrons or other electrically charged particles. The energy produced by this vibration travels in the form of electromagnetic waves. Like a water wave or the wave formed by swinging a rope, a light wave has the properties of wavelength, amplitude, period, frequency, and speed. Figure 1.1a shows light as a wave with those properties. In Figure 1.1a, wavelength is the distance between adjacent crests or troughs, measured in meters, while amplitude is the height of the wave, measured in meters. The period is the time it takes for one complete wave to pass a given point, measured in seconds. The frequency is the number of complete waves that pass a point in one second, measured in inverse seconds, or hertz (Hz). The speed is the horizontal speed of a point on a wave as it propagates, measured in meter/second. For light traveling in vacuum, the speed of light is commonly given the symbol c. It is a universal constant that has the value c = 3 × 108 m/sec. The speed of light in a medium is generally expressed as v = c/n, where n is the refractive index of the medium. Since the propagation direction and the vibration direction of a light wave are perpendicular, light is a transverse ...

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