Spherical Aberration N Telescope

Spherical Aberration Refractor

Focused patterns for 0, 1 8, 1 4,1 3,1 2, and 1.7 wavelengths of lower-order spherical aberration. The aperture is unobstructed. a) normal, OB 33 b) SA -1 8 7 a) normal, OB 33 b) SA -1 8 7 Fig. 10-8. In-focus patterns for a) 0, b) 1 8, c) 1 4, d) 1 3, e) 1 2, and f) 1.7 wavelengths of lower-order spherical aberration. Aperture has a 33 centered circular obstruction. Fig. 10-8. In-focus patterns for a) 0, b) 1 8, c) 1 4, d) 1 3, e) 1 2, and f) 1.7 wavelengths of lower-order spherical...

Pinched and Deformed Optics

Monta Pasa Nadrynnowego Podrynnowego

At the start of each observing session, you should star test for problems that may change with transport of the telescope or a remounting of the optics after maintenance. This chapter will discuss the star-test pattern characteristic of one such warping and will present ways to relieve unusual stresses on the optics. Beyond the image improvements derived by giving careful attention to the deformations, you may be able to avoid catastrophic damage. Edge fractures are common among mirrors with...

Circular Zones and Turned Edges

This chapter discusses zonal defects and a common type of zonal error, a turned edge. It will make four chief points 1 On mirrors of amateur size, interior zones are seldom large enough to be troublesome. 2. Zonal defects can be detected by defocusing a larger amount than is usual. 3 Turned edge is a persistent problem that yields contrasts worse than the smaller aperture inside the turned annulus. 4. Narrow turned edges can be treated by masking or painting the edge. Zones are slight circular...

Accumulated Optical Problems

Spherical Aberration Central Obstruction

What you have been shown thus far is how the individual aberrations and transmission variations can affect the image. More important, however, is the way minor problems add up. The wobbly stack of Fig. 3-1 shows how many errors accumulate as a collection of filters. Even if each filter is relatively unimportant, the total filtration could render the image fuzzy and indistinct. The concept of modulation transfer outlined in Chapter 3 presented a single standard around which we could rally. By...