. Abstract: The author has expanded the information found in his practical 1995 tutorial. Draw line 1 from center C center of the first surface radius through point P1, the point where the entering ray meets the first surface. Both are based on the behavior of a wedged-film configuration. Special Optical Surfaces and Components 5.
During the past nine years, my predecessor, Donald C. For a single element, Eq. Here, the filter is not only in parallel light, its size is the smallest possible. A number of well-centered circular masks of increasing size are inserted successively at the image location and the energy levels are recorded from 0 to 100%. Effects at a single surface -- 8.
Vignetting is the failure of an oblique ray bundle to fill the aperture stop. Modern infrared imaging systems use sensor arrays that are made up of small individual sensing elements, the pixels. The text explores a range of problems illustrating several design issues, with applications in military, industry, aeronautics, space, and medicine, among others. The ratio between the radii 2 and 3 is therefore 1 to 1. The effect is shown in Fig. The ball lens -- 5. The state of the art full-colored guide offers a finished creation to the rules and the perform of calculation, structure, and realizing of optical platforms and lens layout.
Best Shape for a Thin Lens 21 The location of this blur circle of least confusion is located halfway between the sagittal and tangential image shells. It is apparent that the optical gain, which is the ratio between the entrance area of the light pipe and the detector area, is limited. It can save much time in evaluating a given situation during the initial layout phase. The center portion of the inside Maksutov window is the secondary mirror of the basic Cassegrain configuration. The lens used for the reduction of the detector is called the field lens. I also thank my friend and colleague Robert E.
This initial reviewing process has been very helpful to authors in identifying, early in the writing process, the need for additional material or other changes in approach that serve to strengthen the text. Important to remember is the word vapor, i. Sometimes the categories are split between on-axis and off-axis aberrations. Special Optical Surfaces and Components 91 where V All other symbols are shown in Fig. An optical material with an index of refraction very close to this value is sapphire at a wavelength of 3. Smith reveals time-tested methods for designing top-quality lenses. The final result is shown in Fig.
This ray, the marginal principal ray, passes through the center of the aperture stop and terminates at the edge of the exit window. The correcting shell has been placed at the front surface. Positive, or overcorrected spherical aberration, exists when the marginal ray intercepts the optical axis beyond the paraxial focal plane. Negative lenses negative-power lenses have their image surface bent in the other direction. Therefore, there is a compensating effect. The first or front radius of the second element element B is equal to the second radius of element A.
The reciprocal object distance v is defined in Eq. T his concept will be discussed in detail in Chapter 3. This method has been applied in evaluating the performance of the presented examples in the previous chapters. Despite what the title implied, it has very little information on Infrared Systems. We add a thickness of 6 mm to the lens, aspherize the front surface slightly in the optimization process, and obtain a lens that is within the quarter-wave Raleigh limit for both wavelengths, as can be seen from the plots in Fig. It is important to remember that m is positive for the Cassegrain expander and negative for the Gregorian. No part of this publication may be reproduced or distributed in any form or by any means without written permission of the publisher.
It must be added that pupils and windows are not always circular. As an interesting exercise, we use silicon for both elements and make the rear element an aspheric hybrid. The Dewar window of a cooled detector package is another example of that. Defocus with change of temperature -- 7. This is known as spurious resolution. The primary and secondary mirrors form a monolithic element, which was fabricated by single-point diamond turning on an ultra-precision lathe. This has been done to simplify the analysis without impacting the correctness of the general approach.
Over the years, the thermometer was replaced by other detectors. Chapter 3 Best Shapes for Multiple Thin Lenses, Aspherizing, and the Natural Stop Position 3. As mentioned earlier, filters with various thicknesses are frequently inserted into a well-balanced optical system without consideration of the effects discussed above. In a Cassegrain telescope, the pupils are doughnut-shaped, due to the central obstruction of the secondary mirror. A telephoto lens is compact for its long focal length. Conic sections and general aspheres -- 5. The chosen material is CaF2, which can be diamond turned.
This will be done for third-order spherical aberration. These filters vary in their complexity according to the performance demand. Two thin air-spaced elements -- 3. The final subject gradually leads the reader from a single element as an imaging objective for the visible spectrum, the historic Höegh, to a four-element anastigmat. Further configurations are parabolic reflectors and a combination of refractive and reflective elements.