This book illustrates basic practical applications of optical principle. Working models of telescopes, microscopes, photographic lenses, and optical projection systems are diagrammed and explained in full, as are the basic experiments for determining accuracy, power, angular field of view, amount of aberration, and all other necessary facts about the instrument. Throughout the book, only elementary mathematics is used, for the benefit of the student and the beginner in the field of optics.
The author, an assistant professor at the Imperial College of Science and Technology in London, shows how to set up working models of each of the four types of instruments named above, so that the reader can see for himself the effects of changing the focal length, using different types of lenses, rotating the lens, and other experiments. He also includes a number of experiments to illustrate theoretical principles such as the reflection and refraction of light and focal length measurements of concave and convex lenses.
A chapter on the human eye follows, and the author explains how to set up a simple working model of the eye in order to illustrate myopia, astigmatism, hypermetropia, and the visual acuity of the eye. Professor Johnson concludes with an important chapter on the working and testing of optical glass, in which he describes the roughing of lenses, the principles of the grinding and polishing processes, abrasives, edging, angle measurement, and other important steps in the production of optical glass. An appendix is included on the cleaning of glass surfaces, silvering, photographic items, developers, collodion films, and waxes and cements used for various purposes in optical work.
This is a valuable work for the student and the amateur hobbyist as well as for many who use optical instruments in science and industry. It is written clearly and economically, with the needs of the practical worker in the field of optics held constantly in mind.
Practical guide shows how to set up working models of telescopes, microscopes, photographic lenses and projecting systems; how to conduct experiments for determining accuracy, resolving power, more. 234 diagrams.
CHAPTER I-REFLECTION AND REFRACTION
"Experiments illustrating reflection at single, double and multiple mirrors"
"Principles of periscope, binocular prism, roof edge reflection, pentagonal prism, tetrahedron"
Concave and convex mirrors
Laws of refraction
Critical angle and internal reflection
Action of lenses
"Ray tracing methods, graphical and trigonometrical"
CHAPTER II-FOCAL LENGTH MEASUREMENTS
Optical bench
"Focal lengths of " thin " positive and negative lenses"
Two thin lenses in contact
Two thin lenses separated
Newton's method
"Focal length of " thick " lenses"
Magnification method
Foco-collimator
Collimator
Nodal slide method
CHAPTER III-THE EYE
General description with named parts and optical data
Schematic eye
Emmetropia and ametropia
Correction of myopia and hypermetropia
Working model of human eye
Resolving power of eye
Visual acuity limits
Tests and theoretical explanations
CHAPTER IV-THE TELESCOPE
"Model telescopes, astronomical and Galilean types"
Measurement of magnification and angular field of view
Entrance and exit pupils
"Models of Huygenian, Ramsden and four-lens terrestrial eyepieces"
Types of object glass and eyepieces used commerically
"Tests on telescopes for definition, squaring-on, strain, stray light"
"Resolving power, theory and practical tests"
Necessary power of eyepiece
Binocular telescopic instruments
Angular accommodation
Appartus for adjusting binocular telescopes
Wide field of view sighting telescopes
Variable power telescopes
CHAPTER V-THE MICROSCOPE
Hand magnifiers
"Compound microscope, optical bench models and modern instruments"
Correct setting up of the microscope
Numerical aperture
Apertometers
"Resolving power, theory and practical testing"
Necessary magnification to employ
Photo-micrography
Opaque objects
Ultra-violet microscopy at various wavelengths
Reflection microscopes
Electron microscope
CHAPTER VI-PHOTOGRAPHIC LENSES
Aberrations
Principles for reducing coma and astigmatism
"Optical bench models illustrating definition performance for meniscus, symmetrical and anastigmat types of photographic lenses"
Theory with numerical examples illustrating the advantages of various types of glass
Measurement of astigmatic fields
Telephoto lenses
Complete tests on photographic lenses
"Resolving power, theory and practical tests"
"Depth of focus, image space and object space"
Schmidt camera
CHAPTER VII-OPTICAL PROJECTION SYSTEMS
Measurement of solid angle
"Intrinsic brightness, transmission factors, intensity of illumination on projection screens"
Sources of light for projection purposes
Projection of transparencies
Loss of light in projection systems
Projection of opaque objects
"Searchlights, signaling lamps, headlights"
Projection in engineering practice
Physical experiments
Microprojection
"Lighthouse projection systems, marine lanterns, railway signal lamps"
CHAPTER VIII-OPTICAL GLASS: ITS WORKING AND TESTING
Advantages of a variety in optical glasses
Production of optical glass
Annealing
Strain
Homogeneity
Optical constants
Refractometry
"Glass working, principles of grinding and polishing processes"
Abrasives
"Edging, radius of curvature measurements, mechanical and optical"
"Test plates, flat and curved"
Methods of producing test plates
"Angle measurement, goniometer, auto-collimator, naked eye tests"
Non-reflecting films on glass
APPENDIX
Cleaning of glass surfaces
Breath figures
Balsaming
Viscometer for pitch and balsam
Silvering
Photographic items
Graticules
Developers
Webs
Collodion films
Waxes and cements
Sources of light
INDEX