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AFM Instrumentation and Tips
Published in Bharat Bhushan, Handbook of Micro/Nano Tribology, 2020
Realizing that the divergence angle of a light beam reflected from a cantilever is given either by the focal diameter or by the width of the cantilever (whichever is smaller) (Colchero, 1993), it was found that by using a rather broad laser beam with a focal diameter of 50 µm one could safely displace the cantilever for more than 10 µm laterally without any unwanted cross talk, provided the light was incident perpendicularly to the cantilever (Hipp et al., 1992) (see Figure 2.27). This can be achieved with the setup shown in Figure 2.28. A laser diode serves as a light source, and the linearly polarized light passes through a polarizing beam splitter and a quarter wave plate. The laser is focused onto the cantilever. Since the light is incident perpendicularly on the cantilever, its polarization state will not change. For all other angles of incidence, the s- and p-polarized light will have different reflectivities. The cantilever now deflects the light according to the force acting on it. The deflection angles are of the order of microradians and, hence, negligible. The returning circularly polarized light is converted to linear polarized light by the quarter wave plate. The linear polarization state is orthogonal to the incident one. Therefore, the polarizing beam splitter cube now keeps the returning light away from the laser and directs it to the quadrant diode. The main limitation of this setup is the limited scanning range, due to the focal diameter of the laser beam.
Laser Beams, Polarization, and Interference
Published in Walter Fox Smith, Experimental Physics, 2020
We now consider two types of devices that can manipulate polarization: a polarizer and a wave plate. A linear polarizer, commonly just called a polarizer, absorbs the vector component of the electric field that is perpendicular to the transmission axis so that the transmitted light is linearly polarized, as shown in Figure 11.1. A wave plate is made from a birefringent crystal wherein the index of refraction that light experiences depends on the orientation of its polarization. Wave plates have the appearance of thin windows and do not absorb light. Rather, a wave plate introduces a relative phase delay between field components oriented along the slow axis and the fast axis, as shown in Figure 11.2. These two axes are associated with higher and lower refractive indices, respectively.
Introduction and Overview
Published in Russell A. Chipman, Wai-Sze Tiffany Lam, Garam Young, Polarized Light and Optical Systems, 2018
Russell A. Chipman, Wai-Sze Tiffany Lam, Garam Young
Polarizers transmit a known polarization state independent of the incident polarization state. Most common are linear polarizers that transmit linearly polarized light along their transmission axis. A linear polarizer is a device that, when placed in an incident unpolarized beam, produces a beam of light where the electric field vector is oscillating primarily in one plane with only a small component in the perpendicular plane. An ideal polarizer has a transmission of one for the specified polarization state and transmission of zero for the orthogonal polarization state. Polarizers are an example of diattenuators, or partial polarizers, which have two transmissions Tmax and Tmin for two orthogonal polarization states. Diattenuators can be characterized by their diattenuation
Linearly polarized photoluminescence from anisotropic perovskite nanostructures: emerging materials for display technology
Published in Journal of Information Display, 2019
Yong Ge, Linghai Meng, Zelong Bai, Haizheng Zhong
Polarized light plays an important role in modern optoelectronic devices such as liquid crystal display (LCD) backlight [1,2], 3D display systems [3] and polarization photodetection [4,5]. The polarization ratio is a parameter that can measure the degree of polarization, which can be defined as [6] where P is the polarization ratio, I∥ and I⊥ represent the emission intensity parallel and perpendicular to the alignment direction, respectively. In LCD systems, the vertical polarizer filters are widely used to generate polarized light. The process of generating polarized light will decrease the brightness of backlight, causing the loss of energy [7]. The use of polarized light source can improve the energy efficiency, thus the fabrication and application of luminescence materials as polarized light source have attracted great interest of both of material science and optcial engineering.
Design of an achromatic wide-view circular polarizer using normal dispersion films
Published in Journal of Information Display, 2019
Seung-Won Oh, Sang-Hyeok Kim, Jong-Min Baek, Tae-Hoon Yoon
Organic light-emitting diode displays (OLEDs) are emerging as a promising technology for smartphones and televisions [1–4]. OLEDs exhibit advantages like a true black state, vivid colors, good flexibility, and a fast response time. In spite of all these advantages, the sunlight readability of OLEDs is still quite limited because of the strong reflection of the ambient light by the inner metallic electrodes. A circular polarizer (CP) has been commonly used in OLED display panels to suppress the reflection of the ambient light [5–11]. A circular polarizer consists of a linear polarizer and a quarter-wave plate (QWP). A linearly polarized light passed through a polarizer is transformed into a circularly polarized light state while passing through the QWP. Then the light reflected from the reflective electrode of an OLED passes through the QWP again and becomes a linearly polarized light whose polarization is orthogonal to the original input beam, resulting in the elimination of the reflected light.
A MATLAB-based modelling and simulation package for DPS-QKD
Published in Journal of Modern Optics, 2022
Anuj Sethia, Anindita Banerjee
An in-line polarizer passes linearly polarized light while blocking the orthogonal polarization from an unpolarized (or randomly polarized) light source. The orthogonally polarized light is attenuated with a desired extinction ratio such that only a single principle polarization mode traverse through the fibre.