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Lenses
Published in Roshan L. Aggarwal, Kambiz Alavi, Introduction to Optical Components, 2018
Roshan L. Aggarwal, Kambiz Alavi
Focal length of a lens is a function of the distance h of the object rays from the optical axis. Normally, the focal length of a lens is specified for values of h, which are much smaller than the focal length, that is, in the paraxial approximation. For large values of h, the paraxial approximation is not valid. Consequently, the image of an on-axis object is degraded if the diameter of the lens is not much smaller than its focal length. This image defect is known as spherical aberration. The magnitude of the spherical aberration depends on the shape of the lens. The shape factor is given by (Jenkins and White 1976) () q=R2+R1R2−R1
The Importance of Photolithography for Moore’s Law
Published in Lambrechts Wynand, Sinha Saurabh, Abdallah Jassem, Prinsloo Jaco, Extending Moore’s Law through Advanced Semiconductor Design and Processing Techniques, 2018
Lambrechts Wynand, Sinha Saurabh, Abdallah Jassem
The parameters in Figures 3.3 and 3.4, which are listed in Table 3.5, are related within a Cartesian plane and distances toward the right-hand side of each figure are represented as positive quantities, whereas distances toward the left-hand side are represented as negative quantities. The optical axis is the centerline of the optical imaging system and is normally defined by a zero field angle. For thick lenses, as shown in Figure 3.4, the system additionally has two principal planes, or nodal points, as well as two focal planes, also referred to as focal points. If a unity index of refraction in both the object and image planes is assumed, the object and image properties in the imaging system are related such that
Magnetic Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
To understand how GMR works on the atomic level, consider the following analogies. Let us consider a ball to be analogous to a conduction electron. If a person throws a ball between two sets of rollers turning in the same direction (like parallel spin-aligned magnetic layers), the ball tends to go through smoothly. But if the rollers turn in opposite directions, the ball tends to bounce and scatter. Alternatively, the GMR effect may be compared to light passing through optical polarizers. When the polarizers are aligned, light passes through them easily but when their optical axes are rotated with respect to each other, light is prevented from passing across.
Instantaneous mapping of liquid crystal orientation using a polychromatic polarizing microscope
Published in Liquid Crystals, 2023
Mojtaba Rajabi, Oleg Lavrentovich, Michael Shribak
The spectral fan of polarisation ellipses could be assembled from a rotatable linear polariser, achromatic quarter-wave plate (AQWP), and optically active waveplate (OAWP), Figure 1. The polariser and AQWP produce a polarisation ellipse with the major axis parallel to the slow axis of AQWP [24]. The waveplate OAWP is cut perpendicularly to the optical axis of a uniaxial gyrotropic crystal, such as quartz [22,25]. When the polarised light propagates along the optical axis of a gyrotropic crystal, the polarisation ellipse rotates by some angle. The rotation angle is linearly proportional to the OAWP thickness and inversely proportional to the wavelength. The thickness of the waveplate is about 8 mm. The eigen polarisations of OAWP are circular, and the polarisation rotation angle equals half of the phase shift between the eigen polarisations.