Optical telescope

A type of telescope

Collection

zero Useful+1

zero

Optical telescope is used to collect visible light One of telescope , including refracting telescope, reflecting telescope and Schmidt telescope.

Chinese name: Optical telescope
Category: Refracting telescope 、 reflex

Purpose: Astrometry
Famous model: Hooke telescope

catalog

eleven Independent research and development
twelve Technical breakthrough
thirteen Completion site selection

Instrument Introduction

Announce

edit

Optical telescope, using the human eye visible light The telescope that forms the image of stars and galaxies is a kind of telescope used to collect visible light, and through focusing light, it can directly enlarge the image, carry out visual observation or photography, especially for observing the night sky, fixed on the stand Monocular telescope , including hand-held binoculars and telescopes for other purposes.

Type and use

Announce

edit

Optical telescope

Optical telescopes are divided into Refracting telescope , reflecting telescope Schmidt telescope 。 In the early 19th century, refracting telescopes were still the mainstream of astronomy, and the focus of research at that time was Astrometry , location determination of adjacent stars. With the evolution of the times, astronomers began to explore Galaxy Other galaxies, studying the structure of the entire universe Reflecting telescope Will take the place of refracting telescopes.^[1]

The Schmidt telescope has captured many deep and dim Astrophotograph So that astronomers can study and explore billions Light year Far away in the depths of the universe. So the 20th century was Reflecting telescope And Schmidt telescope The 21st century will be the era of radio telescope.

nineteenth century Astronomical telescope Mainstream - Refractive University of Hamburg 80 cm refractor.

The Schmidt telescope, which unifies the language of astronomy in the 20th century, is Australia UKST of.

The mainstream of astronomical telescope in the 20th century - reflective type, which is the 3.5 caliber of Zeiss in Germany Reflecting telescope 。^[2]

Famous model

Announce

edit

Hooke telescope

Optical telescope

In 1917, Hooke Telescope in California Mount Wilson Observatory Completed. Its owner reflector With a diameter of 2.54 meters, it has always been the largest in the world 30 years after its completion Astronomical telescope 。 It is with this telescope that, Edwin Hubble Discovered extragalactic galaxies and found Cosmic expansion Evidence.

Haier telescope

Haier with a diameter of 5.08m Reflecting telescope It is located on the Palomar Mountain in the United States. It was built in the 1930s and 1940s and completed in 1948. The construction technology was a miracle at that time. Although Haier's position as the largest reflective optical telescope has been replaced since 1993, it is still Cosmic exploration Play an important role.

Keck telescope

The largest optics in the world Astronomical telescope , located in Hawaii Mauna Kea 。 Its Gemini KeckI and KeckII were built in 1993 and 1996 respectively. They are all 10 meters in diameter and are composed of 36 hexagonal mirror splices with a diameter of 1.8 meters. The mirror surface is adjusted by the active optical support system controlled by the computer to maintain high precision.

Super telescope

In 1999, European Southern Observatory A super telescope was built in Chile. It is an optical telescope with an equivalent diameter of 16 meters, which is composed of four 8-meter diameter telescopes. These four telescopes can form an interference array for interference observation in pairs, or each telescope can be used alone. It can be observed in different wavebands Supernova And so on.

Pleiades Cluster Telescope

Japanese Pleiades Cluster Telescope It is the single side with the largest diameter in the world reflector Its diameter is 8.3 meters. Located on the Mauna Kea Mountain in Hawaii, the project was completed in 1999. It is said that it took seven years just to polish its super large mirror. The Pleiades Telescope uses active optics and adaptive optics Technology, 261 mechanical fingers support the mirror, which can constantly adjust the shape of the mirror to obtain the best image.

Planetary search

Announce

edit

Exoplanet finder model

“ Exoplanet Searcher ”It is the finishing touch of NASA's space program and is scheduled to be launched in 2012. It brings together human beings Space telescope The essence of technology will emerge in the search for space life. The design idea of the "exoplanet seeker" is similar to that of the space interference telescope, but it has made significant breakthroughs in scale and performance. The retractable mirror array of the space interference telescope extends up to 9 meters, while the mirror array of the "exoplanet seeker" extends up to 100 meters. Using its unprecedented resolution, people will be able to detect that there are dozens of Light year Whether there are planets with similar conditions to the Earth, and further study Extraterrestrial life "Suspense" to get valuable clues.

In short, the 21st century“ Celestial eye ”, will have unprecedented high sensitivity, high resolution field And multi object observation capability. On the whole, their effectiveness in observing the universe will surpass its "Big Brother", the Hubble Space Telescope, so as to broaden the horizon of human exploration of the universe in all directions. For a long time, people looked up to the sky and saw the sun, moon and stars rising in the east and falling in the west The sky is round and the place is round 、 Geocentric theory 、 Heliocentric theory etc. Cosmic model 。 Previously, people could only observe the stars with the naked eye, and the observation range was very limited, so the data obtained was also very limited.

working principle

Announce

edit

For the specific design and detailed information of reflection, refraction and catadioptre telescopes, please refer to Reflecting telescope 、 Refracting telescope and Catadioptric telescope entry

The most basic element in the design drawing is the objective lens for collecting light（ lens (1) Or Concave mirror ）An object at a distance (4) forms a Real image （5）。 This image can be recorded or processed as magnifier Of eyepiece (2) , so that the eyes (3) can see the magnified virtual image (6) in the distance.

Optical telescope

A diagram of the Kepler telescope.

Use two Convex lens imaging The image produced by the telescope is inverted. The telescope and Binoculars use Prism (Generally Proprism ）Or install one or more lenses between the objective lens and the eyepiece to correct the image, so that the upright image can be seen.

Many forms of telescopes will use a secondary mirror (secondary mirror) or even a third lens to fold the light path, which may be an integral part of the optical design（ Cassegrain reflector Similar to others), but there are also telescopes that can be used by placing eyepieces or detectors at more convenient locations in a simpler way. In large telescopes, these additional lenses are usually used to provide a larger field of vision or improve image quality.

Angular resolution

Announce

edit

Ignore atmospheric disturbance（ Visual acuity The influence of image quality and the shortcomings of an optical telescope Angular resolution It depends on the objective lens, that is, the aperture of the telescope.

In fact, the larger the aperture, the better the angular resolution. It should be emphasized here that the angular resolution is not provided for the maximum magnification (or magnification) of the telescope. The maximum magnification provided by the dealer is the upper limit of the telescope magnification. Since the maximum magnification and angular resolution exceed the scope of the objective lens, the image cannot be clearer, and the image quality is usually the worst.

Fixation of large Ground-based telescope , the limit of angular resolution is determined by Visual acuity It was decided that the telescopes currently developed should be placed above the atmosphere to eliminate the influence of air on the angular resolution of the image, that is Space telescope , balloon telescopes and aircraft mounted telescopes（ Cooper Airborne Observatory 、 Stratospheric infrared observatory (SOFIA) or add ground-based telescope adaptive optics And speckle imaging.)

Recently, the synthetic aperture array of optical telescopes has become more practical. Through the combination of a group of small aperture telescopes in space, higher resolution can be obtained under the connection of carefully controlled optical planes. But these Interferometer It can only be used to observe bright objects, such as stars or Active galaxy Nuclear, e.g Betelgeuse The star spot image of can be seen here.

Focal length and focal ratio

Announce

edit

Optical telescope

The focal length determines the configuration of the telescope eyepiece , certain size CCD Or ordinary negative The size of the possible view field. Telescopic Coke ratio (Focal length ratio or f number, that is, photographic terminology“ aperture ”）Yes Focal length And objective lens caliber (diameter) ratio. Therefore, when the aperture (focusing power) is constant, the field of vision with low focal ratio is larger. Wide-angle telescope (like an astrograph) used to track satellites and asteroid , or engaged in cosmic rays Research and sky survey observation. The aberration of low focal ratio telescope is more difficult to eliminate than that of high focal ratio telescope.

Collecting power

Announce

edit

The concentrating power of a telescope is directly related to the objective lens (lens or lens) diameter (i.e caliber ）About. Note that the area of the circle is proportional to the square of the radius. Therefore, when the diameter of the telescope lens is increased by three times, the light collecting force will increase by nine times. The larger the aperture, the more light will be collected; In addition, imaging equipment with high sensitivity (such as CCD ）It can obtain better image quality with less light.

Research telescope

Announce

edit

Almost all large astronomical telescopes used for research are mirrors, because:

Under the use of lens, the whole lens material must be free of defects, uniform and polyphase, while the reflector only needs to polish a perfect surface, which is relatively simple.
In addition to the vacuum environment, light of different colors will have different broadcast speeds when penetrating the medium, which will cause the unique chromatic aberration 。
Large aperture lenses are technically difficult to manufacture and operate. On the one hand, all materials will sag due to gravity, and the highest and relatively heavy lens can only be supported around the lens. On the other hand, the mirror can be supported on the back and other sides of the reflector in addition to the reflector.

The size of optical telescopes increased steadily in the 20th century, doubling between 1910 and 1940, and doubling again between 1940 and 1990. Now the largest telescopes are the 11 meter SALT and Hobby Eberly telescopes, and the 10.4 meter Gran Telescopio Canarias.

In the 1980s, the new generation of telescopes that made technical improvements made great progress, including multi lens telescopes and personal computers that can control lenses. Another major development is the rotating furnace, in which the lenses of the telescope can be made close to the shape (radius of curvature) to be ground by centrifugal force.

Other forms

Announce

edit

Binoculars It is a telescope that can be used simultaneously by combining two monocular telescopes side by side. The main practical advantage of this kind of telescope is not amplification, but dawn or Twilight There is always a bright field of view. And compass The combined monocular or binocular telescope will be used in the army's artillery units and ships Triangulation And terrain (coastal) feature navigation. The hand-held telescope will not be affected Handshock The limit of influence is seven times, so the binoculars with bright field of view and optimal multiple are 7 × 50 specifications.

Because binoculars have a wide field of view, are bright and easy to operate, and are cheaper than professional telescopes Astronomer Commonly used equipment for learning observation at ordinary times, and binoculars with large aperture have become some Astronomer Find new successfully comet Important equipment; In addition, there are also astronomy enthusiasts who try to put two Reflecting telescope Assemble into binoculars.

Independent research and development

Announce

edit

A new type of large machine completely invented by China field Telescope - large sky area optical fiber spectrum Astronomical telescope (LAMOST) is located in Hebei Province Xinglong County Of National Astronomical Observatory Xinglong Observation Base was completed. This marks the first time that China has a place in the type of telescope.

Technically, LAMOST In its reflection Schmidt Both thin mirror active optics and mosaic mirror are used on the correction mirror Active optics Technology has broken through the bottleneck that large field of view of optical telescopes in the world cannot simultaneously have large aperture, making China's active optical technology in the international leading position. Its parallel controllable optical fiber positioning technology solves the problem of accurately positioning 4000 observation targets at the same time, which is an international leading technological innovation.

Each index of the telescope has reached or even exceeded the design requirements. During the commissioning process, a single observation can simultaneously obtain more than 3000 celestial spectra. It has become the largest optical telescope in China and the largest aperture in the world field The telescope is also the telescope with the highest spectral acquisition rate in the world. The acquisition of a large number of optical spectra of celestial bodies is the key to the research of large field of view and large sample astronomy. But up to now, only about 1/10000 of the tens of billions of various celestial bodies recorded by imaging surveys have undergone spectral observations. LAMOST will break through Astronomical research This bottleneck of mid spectral observation has a significant impact on the performance of tens of millions of galaxies a quasar The spectral survey of extragalactic objects will be carried out in extragalactic astrophysics and cosmology Hanoi Astrophysics and Galaxy He made significant contributions to research. Executive Vice President of the Chinese Academy of Sciences Leader of LAMOST Engineering Project Leading Group Bai Chunli At the inauguration ceremony of, The completion and observation of LAMOST will enable China to have the world's leading active optical technology and multi-target spectral observation capability; It will add high-level observation facilities and platforms for Chinese astronomical research; For China Large scale structure of the universe 、 Galaxy structure 、 Dark energy And other related fields to provide necessary conditions and technical support.

Technical breakthrough

Announce

edit

The most innovative part of LAMOST is the reflection formed by splicing 24 hexagonal plane sub mirrors with a diagonal of 1.1 meters Schmidt corrector In the observation process, the computer controls the shape of these sub mirrors to form a series of different high-precision aspherical surfaces in real time, so as to achieve the unique size in the world that cannot be achieved by traditional optics field (Wide angle) Active reflection Schmidt with large aperture optical system In order to accurately obtain a large number of astronomical spectral information. We are together reflector At the same time, thin mirror active optics and mosaic mirror active optics technology are used in the world, which not only advances active optics technology to a new frontier, but also develops a third new type of active optics in the world. We also used parallel controllable optical fiber positioning technology to solve the problem of accurately positioning 4000 observation targets at the same time, which is far more than the current maximum of 600 optical fibers in the world. These are all international leading technological innovations.

The telescope, creatively designed and built by Chinese scientists, has exceeded the previous largest telescope in the world in terms of the combination of aperture, field of view and number of optical fibers field Sky Survey Instrument - America Sloan Digital Sky Survey The telescope also surpassed all the completed or ongoing large field multi celestial body optical fiber spectral survey plans in the world at one fell swoop, becoming the most powerful astronomical observation equipment in the world to obtain celestial body spectra.^[3]

Completion site selection

Announce

edit

On July 21, scientists from the United States and Canada announced that the 30m aperture telescope (TMT), which will become the world's largest optical telescope after completion, was determined to be built on the top of Mauna Kea Mountain in Hawaii. The TMT will be California Institute of Technology , the University of California and the Astronomical Research Association of Canadian Universities, and is expected to start construction in 2011. TMT is expected to cost US $1 billion. The Alliance has received and committed a total of US $300 million in funding, which is less than 1/3 of the plan. The Alliance hopes that the US government, private foundations and foreign partners can make up the remaining funds.^[4-5]

Novice on the road

Growth task Getting Started with Editing Edit Rule Edit by myself

I have questions

Content query Online Service Official post bar Feedback

Complaints and suggestions

Report bad information Failed to appeal through entries Complaint of infringement information Blocking query and unblocking

Jinggong Network Anbei No. 1100000200001