PLate OPtimizer, or PLOP is a CAD program used by amateur telescope makers to design primary mirror support cells for reflecting telescopes. It was developed by telescope maker David Lewis, first described in 1999, [1] and used to simplify calculations needed in the design of mirror support cells. [2] It was based on Toshimi Taki's 1993 program PLATE, [3] with a simplified user interface, thus giving it wide acceptance among makers of large Dobsonian style amateur telescopes, with good support of mirrors as thin as two inches for a diameter of thirty inches. [4]
A basic mirror cell may be built using minimal calculation and simple materials such as wood and outdoor carpet, with a good example being Dobson's original telescopes. However, as amateurs sought to build larger and thinner mirrors, they found such designs inadequate.
Many amateur telescope makers use cells which are designed via equal area rule calculation, using programs such as David Chandler's public domain program, Cell. [5] However, such calculation does not account for mechanical stresses introduced in one part of a telescope mirror by another part, whereas finite element analysis can be used to reduce such stress. Although general finite element analysis programs such as Nastran will work for mirror cells, an advantage of PLOP is that it can be set to ignore deformation that merely results in refocus of a mirror's parabola. [6] PLOP can be used to calculate floating support points for a mirror's axial (rear) support; however, additional tools are needed to calculate potential error from a mirror's lateral (edge) support. [7]
Mirror cell calculations, whether using PLOP or another program, do not overcome errors introduced by gluing the mirror to its cell, excessive tightening of edge supports, nor impingement of the cell structure onto the mirror as result of differential cooling shrinkage. The significantly more complex calculations arising from the support needs of large honeycomb mirrors and those using active optics systems are outside the design parameters of such programs. [8]
A primary mirror is the principal light-gathering surface of a reflecting telescope.
Amateur telescope making is the activity of building telescopes as a hobby, as opposed to being a paid professional. Amateur telescope makers build their instruments for personal enjoyment of a technical challenge, as a way to obtain an inexpensive or personally customized telescope, or as a research tool in the field of astronomy. Amateur telescope makers are usually a sub-group in the field of amateur astronomy.
A refracting telescope is a type of optical telescope that uses a lens as its objective to form an image. The refracting telescope design was originally used in spyglasses and astronomical telescopes but is also used for long-focus camera lenses. Although large refracting telescopes were very popular in the second half of the 19th century, for most research purposes, the refracting telescope has been superseded by the reflecting telescope, which allows larger apertures. A refractor's magnification is calculated by dividing the focal length of the objective lens by that of the eyepiece.
A reflecting telescope is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternative to the refracting telescope which, at that time, was a design that suffered from severe chromatic aberration. Although reflecting telescopes produce other types of optical aberrations, it is a design that allows for very large diameter objectives. Almost all of the major telescopes used in astronomy research are reflectors. Many variant forms are in use and some employ extra optical elements to improve image quality or place the image in a mechanically advantageous position. Since reflecting telescopes use mirrors, the design is sometimes referred to as a catoptric telescope.
A Dobsonian telescope is an altazimuth-mounted Newtonian telescope design popularized by John Dobson in 1965 and credited with vastly increasing the size of telescopes available to amateur astronomers. Dobson's telescopes featured a simplified mechanical design that was easy to manufacture from readily available components to create a large, portable, low-cost telescope. The design is optimized for observing faint, deep-sky objects such as nebulae and galaxies. This type of observation requires a large objective diameter of relatively short focal length and portability for travel to less light-polluted locations.
The Newtonian telescope, also called the Newtonian reflector or just a Newtonian, is a type of reflecting telescope invented by the English scientist Sir Isaac Newton, using a concave primary mirror and a flat diagonal secondary mirror. Newton's first reflecting telescope was completed in 1668 and is the earliest known functional reflecting telescope. The Newtonian telescope's simple design has made it very popular with amateur telescope makers.
The Gemini Observatory comprises two 8.1-metre (26.6 ft) telescopes, Gemini North and Gemini South, situated in Hawaii and Chile, respectively. These twin telescopes offer extensive coverage of the northern and southern skies and rank among the most advanced optical/infrared telescopes available to astronomers. (See List of largest optical reflecting telescopes).
The Hale Telescope is a 200-inch (5.1 m), f/3.3 reflecting telescope at the Palomar Observatory in San Diego County, California, US, named after astronomer George Ellery Hale. With funding from the Rockefeller Foundation in 1928, he orchestrated the planning, design, and construction of the observatory, but with the project ending up taking 20 years he did not live to see its commissioning. The Hale was groundbreaking for its time, with double the diameter of the second-largest telescope, and pioneered many new technologies in telescope mount design and in the design and fabrication of its large aluminum coated "honeycomb" low thermal expansion Pyrex mirror. It was completed in 1949 and is still in active use.
The NASA Infrared Telescope Facility is a 3-meter (9.8 ft) telescope optimized for use in infrared astronomy and located at the Mauna Kea Observatory in Hawaii. It was first built to support the Voyager missions and is now the US national facility for infrared astronomy, providing continued support to planetary, solar neighborhood, and deep space applications. The IRTF is operated by the University of Hawaii under a cooperative agreement with NASA. According to the IRTF's time allocation rules, at least 50% of the observing time is devoted to planetary science.
The MMT Observatory (MMTO) is an astronomical observatory on the site of Fred Lawrence Whipple Observatory. The Whipple observatory complex is located on Mount Hopkins, Arizona, US in the Santa Rita Mountains. The observatory is operated by the University of Arizona and the Smithsonian Institution, and has a visitor center in nearby Amado, Arizona. The MMTO is the home of the MMT, which has a primary mirror 6.5 m in diameter. The name comes from the six smaller mirrors originally used before the single primary mirror was installed in 1998. The primary mirror has a special lightweight honeycomb design made by the University of Arizona's Steward Observatory Mirror Laboratory. The MMT is housed in a building which allows the walls and roof around the telescope to be completely rolled back, allowing it to cool down very quickly in order to improve observation.
Visible-light astronomy encompasses a wide variety of observations via telescopes that are sensitive in the range of visible light. Visible-light astronomy is part of optical astronomy, and differs from astronomies based on invisible types of light in the electromagnetic radiation spectrum, such as radio waves, infrared waves, ultraviolet waves, X-ray waves and gamma-ray waves. Visible light ranges from 380 to 750 nanometers in wavelength.
A segmented mirror is an array of smaller mirrors designed to act as segments of a single large curved mirror. The segments can be either spherical or asymmetric. They are used as objectives for large reflecting telescopes. To function, all the mirror segments have to be polished to a precise shape and actively aligned by a computer-controlled active optics system using actuators built into the mirror support cell.
A honeycomb mirror is a large mirror usually used as the primary mirror in astronomical reflecting telescopes whose face is supported by a ribbed structure that resembles a honeycomb. The design provides sufficient rigidity for ultra-high-precision optics while reducing the weight of the mirror. The reduced weight, in turn, allows smaller, lighter support and control structures, reducing the overall cost of the telescope. The term may also refer to mirrors made up of a coordinated set of individual hexagonal mirrors.
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally it was an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects – an optical telescope. Nowadays, the word "telescope" is defined as wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors.
A whippletree, or whiffletree, is a mechanism to distribute force evenly through linkages. It is also referred to as an equalizer, leader bar, or double tree. It consists of a bar pivoted at or near the centre, with force applied from one direction to the pivot and from the other direction to the tips. Several whippletrees may be used in series to distribute the force further, such as to simulate pressure over an area as when applying loading to test airplane wings. Whippletrees may be used either in compression or tension. They were also used for subtraction and addition calculations in mechanical computers. Tension whippletrees are used in artful hung mobiles, such as those by artist Alexander Calder.
In astronomy, a mirror support cell - more commonly mirror cell - is a component of a reflecting telescope that supports the mirror in place to hold optical alignment, allow collimation adjustment, and protect it from falling out. The common usage of the word denotes the cell that holds the primary mirror (M1), however technically it could also be used to denote the support assembly for the secondary mirror (M2) or other mirrors.
The Foucault knife-edge test is an optical test to accurately measure the shape of concave curved mirrors. It is commonly used by amateur telescope makers for figuring primary mirrors in reflecting telescopes. It uses a relatively simple, inexpensive apparatus compared to other testing techniques.
The Linden Observatory Complex is a heritage-listed former observatory and manufacture of optical precision implements and now residence, museum, observatory, education facility and meeting venue located at 91 – 111 Glossop Road, Linden, City of Blue Mountains, New South Wales, Australia. It was designed and built by Ken Beames from 1938 to 1948. It is also known as K Beames Engineering Co. The property is owned by the Linden Observatory Trust. It was added to the New South Wales State Heritage Register on 5 March 2010.
The Leighton Radio Telescopes are 10.4 meter parabolic dish antennas designed by Robert B. Leighton in the 1970s, which were fabricated on the Caltech campus during the 1970s and 1980s. The telescope surfaces reached an accuracy of 10 microns RMS, allowing observations throughout the millimeter and submillimeter bands. In all, eight of these telescopes were made. They were used as the six elements of the Owens Valley Radio Observatory (OVRO) millimeter interferometer in California, and as single telescopes at the Caltech Submillimeter Observatory in Hawaii and the Raman Research Institute (RRI) at Bangalore, India. In the spring of 2005, the six Leighton telescopes in Owens Valley were moved to a high mountain site in the White Mountains to form the core of the CARMA array of 25 telescopes. The CARMA array was decommissioned in 2015 at which time the Leighton telescopes were moved back to OVRO, where they are now being repurposed for different projects including the CO Mapping Array Pathfinder (COMAP), the Event Horizon Telescope (EHT), and various transient detection projects.
