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What You Need to Know About Applied Photographic Optics.pdf: A Review and Summary



Introduction




Applied Photographic Optics.pdf is a book that provides a comprehensive and authoritative reference on all aspects of photographic lenses and associated optical systems. It covers topics such as optical theory, aberrations, lens testing, depth of field, development of photographic lenses, general properties of lenses, wide-angle lenses, telephoto lenses, video lenses, viewfinder systems, camera movements, projection systems and 3-D systems.




Applied Photographic Optics.pdf



The author of the book is Sidney Ray, who is a senior lecturer in digital and photographic imaging at the University of Westminster. He has over 40 years of experience in teaching and research in optics and photography. He is also a Fellow of the British Institute of Professional Photography (BIPP), the Master Photographers Association (MPA) and the Royal Photographic Society (RPS).


The book is intended for anyone who wants to learn more about the optical principles and applications of photographic lenses, from students to practitioners or specialists working with visual and digital media. It is also a valuable resource for optical engineers and designers who need to understand the requirements and limitations of photographic optics.


Optical theory




The first part of the book deals with the basic concepts and laws of optics that are essential for understanding how lenses and optical systems work. It covers topics such as:


Light and energy




This chapter explains the dual nature of light, which can behave as both a wave and a particle. It also describes the properties of electromagnetic waves, such as wavelength, frequency, amplitude and phase. It introduces the electromagnetic spectrum, which ranges from gamma rays to radio waves, and the visible spectrum, which is the part of the electromagnetic spectrum that humans can perceive with their eyes. It also discusses the spectral power distribution of different light sources, such as sunlight, tungsten lamps and fluorescent lamps, and how they affect the detectors, such as film or digital sensors, that record the light. Finally, it introduces the concept of photometry, which is the measurement of light in terms of its perceived brightness by human vision.


Properties of light




This chapter describes how light interacts with matter and changes its direction, intensity and colour. It covers topics such as:


  • Transmission: the passage of light through a medium, such as air, glass or water. It explains the concepts of transmittance, colour transmission, optical transmission density and optical path length.



  • Absorption: the loss of light energy by a medium due to conversion into heat or other forms of energy. It explains the absorption law, spectrally selective absorption, heat filters and black filters.



  • Reflection: the bouncing back of light by a surface, such as a mirror or a water surface. It explains the laws of reflection, types of reflection (specular or diffuse), reflection from dielectric surfaces (such as glass or water) and metal surfaces (such as silver or gold), laser speckle and polarization by reflection.



  • Refraction: the bending of light by a medium due to change in its speed. It explains the laws of refraction, total internal reflection, Snell's window, displacement, deviation, scratch treatment, double refraction and graded refractive index.



  • Dispersion: the separation of light into its component colours by a medium due to variation in its refractive index with wavelength. It explains wavelength dependence and dispersion by diffraction (such as by a prism or a diffraction grating).



  • Scattering: the spreading of light by small particles in a medium due to random changes in its direction. It explains particle size and types of scattering (Rayleigh or Mie).



  • Interference: the superposition of two or more waves of light resulting in constructive or destructive interference. It explains conditions for interference, producing interference (such as by thin films or Michelson interferometer), Newton's rings and fringe visibility.



  • Diffraction: the bending of light around obstacles or apertures due to its wave nature. It explains Fraunhofer diffraction (such as by a slit or a circular aperture), the diffraction grating, the zone plate and spatial filtering.



  • Polarization: the orientation of the electric field vector of an electromagnetic wave in a plane perpendicular to its direction of propagation. It explains natural light, polarized light and polarizers, elliptically polarized light and circularly polarized light.



  • Attenuation: the reduction of light intensity by a medium due to absorption, scattering or reflection. It explains inverse square law of illumination and Lambert's cosine law.



Image formation by simple optical systems




This chapter describes how images are formed by simple optical devices, such as pinholes, simple lenses and simple mirrors. It covers topics such as:


  • Types of images: real or virtual, inverted or erect, magnified or reduced.



  • The pinhole: an aperture that allows light to pass through without refraction or reflection. It explains how it forms an inverted image on a screen, its advantages (such as infinite depth of field) and disadvantages (such as low brightness and resolution).



  • Simple lenses: thin transparent elements that refract light according to their shape (convex or concave) and material (refractive index). It explains definitions (such as principal axis, optical centre, focal point, focal length), image formation by thin lenses (using ray diagrams), lens formulae (such as lens conjugate equation, Newton's equation, such as spherical aberration, coma, astigmatism, field curvature and distortion).



  • Simple mirrors: reflective surfaces that reflect light according to their shape (plane or curved) and material (metal or dielectric). It explains image formation by plane mirrors (using ray diagrams), image formation by spherical mirrors (using ray diagrams and mirror formulae), image formation by aspherical mirrors (such as parabolic or elliptical mirrors) and imaging limitations (such as aberrations).



  • Image characteristics: orientation (inverted or erect), shape (distorted or undistorted), magnification (linear or angular) and brightness (luminance or illuminance).



  • Image construction by graphical methods: using ray diagrams to locate the position, size and orientation of images formed by simple optical systems.



  • Image properties by calculation: using formulae to determine the focal length, object distance, image distance, magnification and brightness of images formed by simple optical systems.



  • Imaging limitations: the factors that affect the quality and accuracy of images formed by simple optical systems, such as aberrations, diffraction, interference, polarization and attenuation.



Image formation by compound lenses




This chapter describes how images are formed by compound lenses, which are combinations of two or more simple lenses. It covers topics such as:


  • Cardinal planes: the principal planes of a compound lens system that define its imaging properties. It explains how to locate the cardinal planes of a compound lens system using graphical or analytical methods.



  • Rear nodal point: the point on the principal axis of a compound lens system where the rays from an object at infinity appear to diverge from. It explains how to locate the rear nodal point of a compound lens system using graphical or analytical methods.



  • The thick lens: a single lens element that has a finite thickness and two curved surfaces. It explains how to use formulae to determine the focal length, principal points, nodal points and magnification of a thick lens.



  • Thick lens combinations: combinations of two or more thick lenses. It explains how to use formulae to determine the effective focal length, principal points, nodal points and magnification of thick lens combinations.



Combinations of elements




This chapter describes how images are formed by combinations of different optical elements, such as lenses, mirrors, prisms and beamsplitters. It covers topics such as:


  • Thin lens combinations: combinations of two or more thin lenses that are separated by a small distance. It explains how to use formulae to determine the effective focal length, back focal length and back focal distance of thin lens combinations.



  • Specific combinations: examples of common thin lens combinations that have specific imaging properties, such as positive-positive systems (such as telephoto lenses), positive-negative systems (such as retrofocus lenses), negative-positive systems (such as wide-angle lenses) and varifocal system (such as zoom lenses).



  • Telescopes: optical instruments that magnify distant objects using two lenses or mirrors. It explains the types of telescopes (such as refracting or reflecting telescopes), their components (such as objective lens or mirror, eyepiece lens or mirror), their characteristics (such as magnification, field of view, exit pupil) and their applications (such as astronomical or terrestrial telescopes).



  • The compound microscope: an optical instrument that magnifies small objects using two lenses. It explains the components of a compound microscope (such as objective lens, eyepiece lens, condenser lens), their characteristics (such as magnification, resolution, numerical aperture) and their applications (such as biological or metallurgical microscopy).



  • Field flatteners: optical elements that correct the curvature of field caused by some lenses. It explains how field flatteners work (by introducing opposite curvature) and where they are used (such as in photographic lenses or microscopes).



  • Relay systems: optical systems that transfer an image from one plane to another without changing its size or orientation. It explains how relay systems work (by using two lenses with equal focal lengths) and where they are used (such as in periscopes or endoscopes).



Optical components and their imaging roles




This chapter describes the various optical components that can be used to manipulate light and form images. It covers topics such as:


  • Lenses: thin or thick transparent elements that refract light according to their shape and material. It explains the types of lenses (such as spherical or aspherical lenses), their advantages and disadvantages (such as chromatic aberration or spherical aberration) and their applications (such as in cameras or projectors).



  • Mirrors: reflective surfaces that reflect light according to their shape and material. It explains the types of mirrors (such as curved or plane mirrors), their advantages and disadvantages (such as image inversion or ghost images) and their applications (such as in telescopes or lasers).



  • Beamsplitters: optical devices that split a beam of light into two or more beams with different directions, intensities or polarizations. It explains the types of beamsplitters (such as cube or plate beamsplitters), their advantages and disadvantages (such as loss of light or polarization effects) and their applications (such as in interferometers or holography).



  • Optical flats and windows: flat transparent elements that transmit light without changing its direction or intensity. It explains the types of optical flats and windows (such as parallel or wedge flats or windows), their advantages and disadvantages (such as high accuracy or air gap interference) and their applications (such as in testing or protection).



  • Cylindrical lenses: lenses that have different curvatures in different planes, resulting in different focal lengths for different orientations. It explains how cylindrical lenses work (by focusing light into a line instead of a point) and where they are used (such as in astigmatism correction or laser diodes).



  • Lenticular devices: devices that consist of arrays of small lenses that create different images for different viewing angles. It explains how lenticular devices work (by using parallax) and where they are used (such as in 3-D displays or security features).



  • Prisms: transparent elements that have two or more plane surfaces that refract light at an angle. It explains the types of prisms (such as right-angle or roof prisms), their advantages and disadvantages (such as dispersion or deviation) and their applications (such as in binoculars or spectroscopes).



  • Fresnel lenses and mirrors: optical devices that consist of concentric rings of prisms that focus light into a point. It explains how Fresnel lenses and mirrors work (by reducing the thickness and weight of conventional lenses and mirrors) and where they are used (such as in lighthouses or solar concentrators).



  • Optical fibres: thin flexible strands of glass or plastic that transmit light by total internal reflection. It explains the types of optical fibres (such as step index or graded index fibres, rods and lenses), their advantages and disadvantages (such as low loss or dispersion) and their applications (such as in communication or illumination).



  • Holographic optical elements: optical devices that record the interference pattern of two coherent beams of light on a photosensitive material. It explains how holographic optical elements work (by reconstructing the original wavefront when illuminated by a reference beam) and where they are used (such as in 3-D imaging or optical storage).



  • Diffractive optical elements: optical devices that use diffraction to manipulate light. It explains the types of diffractive optical elements (such as gratings or zone plates), their advantages and disadvantages (such as high efficiency or wavelength dependence) and their applications (such as in spectroscopy or microscopy).



  • Micro lenses: miniature lenses that have diameters ranging from micrometres to millimetres. It explains how micro lenses work (by using microfabrication techniques) and where they are used (such as in integrated optics or digital cameras).



  • Opto-electronic devices: devices that convert light into electrical signals or vice versa. It explains the types of opto-electronic devices (such as liquid crystal displays [LCDs], light emitting diodes [LEDs] or charge coupled devices [CCDs]), their advantages and disadvantages (such as low power consumption or noise) and their applications (such as in displays or sensors).



Thin-layer coatings




This chapter describes the use of thin layers of materials that are applied to optical surfaces to modify their reflectance or transmittance properties. It covers topics such as:


  • Light losses by surface reflections: the reduction of light intensity by reflection at the interface between two media with different refractive indices. It explains how to calculate the reflectance and transmittance of a surface using Fresnel's equations.



  • Single anti-reflection layers: thin layers of material that have a refractive index that is the geometric mean of the refractive indices of the two media that it separates. It explains how single anti-reflection layers work (by reducing the reflectance to zero at a specific wavelength and angle of incidence) and where they are used (such as in lenses or filters).



  • Double anti-reflection layers: two thin layers of material that have different refractive indices and thicknesses that are designed to reduce the reflectance over a wider range of wavelengths and angles of incidence. It explains how double anti-reflection layers work (by creating destructive interference for the reflected waves) and where they are used (such as in solar cells or optical instruments).



  • Multiple anti-reflection layers: more than two thin layers of material that have different refractive indices and thicknesses that are designed to reduce the reflectance over an even wider range of wavelengths and angles of incidence. It explains how multiple anti-reflection layers work (by using an optimization algorithm to find the best combination of parameters) and where they are used (such as in high-performance optical systems or coatings).



  • Mirror coatings: thin layers of material that have a high reflectance and low transmittance for a specific range of wavelengths and angles of incidence. It explains the types of mirror coatings (such as metal substrate or dielectric substrate), their advantages and disadvantages (such as high reflectance or low durability) and their applications (such as in mirrors or lasers).



  • Dielectric filters: thin layers of material that have a high transmittance for a specific range of wavelengths and low transmittance for other wavelengths. It explains the types of dielectric filters (such as dichroic filters or gradient index filters), their advantages and disadvantages (such as high selectivity or narrow bandwidth) and their applications (such as in colour separation or optical communication).



  • Coating methods: the techniques that are used to deposit thin layers of material on optical surfaces. It explains the types of coating methods (such as evaporation or sputtering), their advantages and disadvantages (such as low cost or high uniformity) and their applications (such as in mass production or custom coating).



Aberrations defects in imaging systems




This chapter describes the deviations from ideal image formation by optical systems due to various factors, such as lens shape, aperture size, wavelength or object position. It covers topics such as:


  • Image formation: the process of forming an image by an optical system using paraxial optics, which assumes that light rays are close to the principal axis and make small angles with it. It explains the concepts of the perfect lens, which forms a perfect image without any aberrations, and failure of paraxial optics, which causes monochromatic aberrations, which are aberrations that occur for a single wavelength of light.



  • Surface contributions: the contributions of each surface of an optical system to the total aberrations. It explains the concepts of transverse ray aberrations, which are deviations from ideal image points in a plane perpendicular to the principal axis, wavefront aberrations, which are deviations from ideal spherical wavefronts, aberration terms, which are coefficients that quantify the amount of each type of aberration, Seidel aberration coefficients, which are five primary aberration terms that describe third-order aberrations, ray aberrations as Seidel sums, which are expressions that relate ray aberrations to Seidel coefficients, and other methods, such as Zernike polynomials or spot diagrams, that can be used to describe aberrations.



  • Spherical aberration: an aberration that causes rays from a point on the principal axis to focus at different points along the principal axis depending on their distance from it. It explains how spherical aberration occurs in thin lens imagery, how it can be corrected by using aspheric surfaces, floating elements or portrait lenses, and how it can cause additional aberration, such as longitudinal chromatic aberration.



  • Coma: an aberration that causes rays from a point off the principal axis to form a comet-shaped image instead of a point image. It explains how coma occurs in optical systems with spherical surfaces, how it can be corrected by using aspheric surfaces or symmetrical systems, and how it can affect image quality, such as contrast or resolution.



Astigmatism: an aberration that causes rays from a point off the principal axis to focus at different points in two perpendicular planes depending on th


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