Refracting telescopes are those that employ lenses, and reflecting telescopes are those that use concave parabolic mirrors. Reflecting telescopes focus light by use of mirrors instead of lenses. To get the light from the telescope, a convex mirror collects it and reflects it back to a focal point. Another mirror directs the light to an eyepiece. This eliminates the issues associated with supporting the lens in a refractor telescope. It also helps with the light losses caused by light traveling through thick pieces of glass. But even these telescopes have their advantages and disadvantages. But before that let’s understand how reflecting telescopes work.
Working Of Reflecting Telescopes
Reflecting telescopes are comparable to refracting telescopes, but they’re a little more technical. They are reflecting telescopes because they employ mirrors to internally reflect light. The light enters at one end and reflects by a concave-shaped mirror to a smaller mirror at the other end. This mirror reflects light into an eyepiece, which is normally located on the telescope’s side. It can adjust to change the focus sharpness.
Advantages:
1. Less Aberration
Reflecting telescopes capture light through mirrors. Mirrors are simpler to make than lenses. They are constructed of an optical glass and cannot have any occlusions because light must pass entirely through them. Furthermore, mirrors have minimal spherical aberration. This means light scattering that occurs by lenses does not completely focus on a single point. Mirrors reflect all wavelengths of light equally. Because reflected light does not disperse according to wavelength, all wavelengths will reflect off the mirror in the same way. This way, reflecting telescopes are not prone to chromatic aberration.
Cost Effective
For an Optical Mirrors Supplier In India, reflecting telescopes are cheaper to manufacture because they use mirrors instead of lenses. Smaller telescopes, and especially those used to observe a point on the Earth’s surface, use lenses. Reflecting telescopes of equivalent size are far less expensive to make. A reflector’s telescope tube is shorter than a refractor’s tube of the same diameter. This lowers the cost of the tube and makes it easier and less expensive to manufacture.
Durability
Mirrors can be made more huge and robust than lenses since they are way easier to make. Furthermore, because only one side of the mirror focuses the light, the other side can be up against a wall. This permits the mirror to be much larger than a lens, which makes them suitable for space observation. More light can be directed to the eyepiece if the collection device is larger.
Disadvantages:
Maintenance And Alignment
The tube of a reflector telescope is open to the elements. So they must be cleaned periodically due to their size and the design of an open tube assembly. It must be corrected every time it is cleaned, which can be costly. They can quickly become misaligned as a result of knocks and bumps, as well as temperature fluctuations. They are prone to spherical aberrations, which can degrade image quality. This will happen if the mirrors and other optics are not at the same temperature as the outside air. A fuzzy or distorted image arises from an unaligned telescope.
Surface Issues
A telescope’s mirror can be huge due to its single reflective surface, but it is also prone to the air. Original reflecting mirrors have a silver surface, which tarnishes in the open air. To maintain these telescopes clear, they need to be polished very frequently. A lot of Optical Products Maufacturers now cover mirrors in reflecting telescopes with aluminum. It oxidizes as well but is clear and requires less polishing. Even with modern telescopes, the reflecting surface’s metal coating needs to renew after years of use.
Different Mirror Shapes
Various reflectors use mirrors of various shapes. All incoming light beams focus to a single point using parabolic reflectors. The coma is a flaw in parabolic mirror images. It causes images far from the center of the field of view to elongate. The spherical mirror surface is simple to construct. However the focal lengths of different regions of the spherical mirror differ slightly. As a result, the images will be a little blurry.
Even with these disadvantages, Reflecting telescopes are extraordinarily popular these days. Many popular telescope models use the design of reflecting telescopes. Furthermore, the reflected telescope concept is expanding to other wavelengths of light. X-ray telescopes use the reflection principle to create image forming optics.
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