Reflector binoculars - is there such a thing?

[tballou]

Would it be possible, and has it already been done, to construct a set of hand help binoculars, or maybe even a headset type device, that would use two mirrors instead of lenses? I.e. a set of reflector binoculars? It seems to me that some kind of lightweight headset with 2 mirrors of approximately 3-5 inches diameter and a relatively short focal length could provide a very interesting viewing experience. Has this already been done?

[Chris Peterson]

Would it be possible, and has it already been done, to construct a set of hand help binoculars, or maybe even a headset type device, that would use two mirrors instead of lenses? I.e. a set of reflector binoculars? It seems to me that some kind of lightweight headset with 2 mirrors of approximately 3-5 inches diameter and a relatively short focal length could provide a very interesting viewing experience. Has this already been done?

I've never seen such (excepting large binocular telescopes designed along these lines). It's not clear what the advantage would be- reflectors provide economy for larger apertures, but not much at very small sizes. And on-axis reflector designs have central obstructions, which can be a real problem for daytime viewing. There are practical limits on aperture that are determined by the maximum magnification and the size of the eye's entrance pupil. Few people can deal with more than 10-12X magnification for a hand held instrument. That means there's little value to an aperture greater than about 25mm for daytime use, or 80mm at night.

A binocular with a 5-inch aperture would need to operate at 60X in the daytime, and 18X at night (to deliver the full aperture's worth of light to the eye). Both are outside the magnification range that is acceptable for hand held operation.

[neufer]

Would it be possible, and has it already been done, to construct a set of hand help binoculars, or maybe even a headset type device, that would use two mirrors instead of lenses? I.e. a set of reflector binoculars? It seems to me that some kind of lightweight headset with 2 mirrors of approximately 3-5 inches diameter and a relatively short focal length could provide a very interesting viewing experience. Has this already been done?

I've never seen such (excepting large binocular telescopes designed along these lines).

Explanation: The imposing structure in the foreground houses the Large Binocular Telescope (LBT), on Mount Graham, Arizona. Inside, the two 8.4 meter diameter mirrors of the LBT really are side-by-side on a common mount, an arrangement mimicking the design of more modest optical equipment usually carried around the neck. While not exactly portable, the benefits of the large scale binocular configuration adopted include an increase in sensitivity over a single mirror telescope and high resolution imaging for faint objects over a relatively wide field of view. An international collaboration operates the LBT Observatory.

<<The Large Binocular Telescope is located on 10,700-foot Mount Graham in the Pinaleno Mountains of southeastern Arizona and is a part of the Mount Graham International Observatory. The LBT is one of the world's highest resolution and most technologically advanced optical telescopes, capable of creating images in the near-infrared with 10 times the resolution of the Hubble Space Telescope. The telescope is expected to be fully operational in 2009. The LBT has a light-collecting area equivalent to a single 11.8-metre (39 ft) surface and will combine light to produce the image sharpness equivalent to a single 22.8-metre (75 ft) telescope. It is located on 10,480-foot (3,190 m) Mount Graham in southeastern Arizona in the United States.>>

[astrolabe]

Hello All,

Anyone for tri-oculars? Triangulation works in locating geo objects as well as gaining accurate info on one's position. Kind of a 3-D (2D?) locator if you will.

[neufer]

Hello All,

Anyone for tri-oculars? Triangulation works in locating geo objects as well as gaining accurate info on one's position. Kind of a 3-D (2D?) locator if you will.

How about quadr-oculars?

Explanation: The Earth's rotation gives a continually changing view to all Earth observers, including those measuring the universe at the Paranal Observatory. The observatory's four, massive 8.2 meter telescope units are situated on top of the 2,600 meter high mountain, Cerro Paranal, in the dry Atacama Desert in northern Chile. The individual unit telescopes can be used separately or in combination. Their names, Antu, Kueyen, Melipal, and Yepun, are taken from the Mapuche language. Fittingly they translate to Sun, Moon, Evening Star, and Southern Cross. Together they are fittingly known as the European Southern Observatory's Very Large Telescope. A higher time resolution version of the above movie is available here.

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Explanation: The sharpest image ever of Betelgeuse shows a mammoth star that is slowly evaporating. Betelgeuse (sounds a lot like "beetle juice"), also known as Alpha Orionis, is one of the largest and brightest stars known. The star is a familiar orange fixture easily visible to the unaided eye toward the constellation of Orion. This recent image from the Very Large Telescope in Chile resolves not only the face of Betelgeuse, but a large and previously unknown plume of surrounding gas. This plume gives fresh indications of how the massive star is shedding mass as it nears the end of its life. Conversely, a series of previous observations indicate that the surface of Betelgeuse has noticeably shrunk, on the average, over the past decade. If Betelgeuse, a red supergiant star about 640 light years distant, were placed at the center of our Solar System, the plume would extend past the orbit of Jupiter. Since Betelgeuse is known to change its brightness irregularly, future observations may determine if changes its appearance irregularly as well. Betelgeuse is a candidate to undergo a spectacular supernova explosion almost anytime in the next few thousand years.

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<<The Very Large Telescope (VLT) is a system of four separate optical telescopes (the Antu telescope, the Kueyen telescope, the Melipal telescope, and the Yepun telescope) organized in an array formation, built and operated by the European Southern Observatory (ESO) at the Paranal Observatory on Cerro Paranal, a 2,635 m high mountain in the Atacama desert in northern Chile. Each telescope has an 8.2 m aperture. The array is complemented by four movable Auxiliary Telescopes (ATs) of 1.8 m aperture. Working together in so-called interferometric mode, the telescopes can achieve an angular resolution of around 1 milliarcsecond, equivalent to the gap between the headlights of a car as observed from the same distance as between the Earth to the Moon.

The VLT consists of an arrangement of four large (8.2 meter diameter) telescopes, and optical elements which can combine them into an astronomical interferometer (VLTI) which is used to resolve small objects. The interferometer also includes a set of four 1.8 meter diameter movable telescopes dedicated to interferometric observations. The 8.2 meter telescopes have been named after some astronomical objects in the local Mapuche language: Antu (The Sun), Kueyen (The Moon), Melipal (The Southern Cross), and Yepun (Venus).

The VLT 8.2 meter telescopes was originally designed to be operated in three modes[2]:

* as a set of four independent telescopes (this is the primary mode of operation). With one such telescope, images of celestial objects as faint as magnitude 30 can be obtained in a one-hour exposure. This corresponds to seeing objects that are four billion times fainter than what can be seen with the unaided eye.
* as a single large coherent interferometric instrument (the VLT Interferometer or VLTI), for extra resolution. This mode is occasionally used, only for observations of relatively bright sources with small angular extent.
* as a single large incoherent instrument, for extra light-gathering capacity. The instrumentation required to bring the light to a combined incoherent focus was not built. Recently, new instrumentation proposals have been put forward for making this observing mode available[3]. Multiple telescopes are sometimes independently pointed at the same object, either to increase the total light-gathering power, or to provide simultaneous observations with complementary instruments.

The VLTs are equipped with a large set of instruments permitting observations to be performed from the near-UV to the mid-IR (ie a large fraction of the light wavelengths accessible from the surface of the Earth), with the full range of techniques including high-resolution spectroscopy, multi-object spectroscopy, imaging, and high-resolution imaging. In particular, the VLT has several Adaptive optics systems, which at infrared wavelengths correct for the effects of the atmospheric turbulence, providing images almost as sharp as if the telescope were in space. In the near-IR, the Adaptive Optics images of the VLT are up to three times sharper than those of the Hubble Space Telescope, and the spectroscopic resolution is many times better than Hubble. The VLTs are noted for their high level of observing efficiency and automation.

The principal role of the main VLT telescopes is to operate as four independent telescopes. The interferometry (combining light from multiple telescopes) is used about 20 percent of the time for very high-resolution on bright objects e.g. Betelgeuse.

Additionally, the four 8.2 m telescopes are accompanied by four smaller Auxiliary Telescopes of 1.8 m each (two operational in 2005, the other two in 2006), which can be placed on different positions around the four big telescopes in order to provide better interferometric observations.

The VLT is operated by the European Southern Observatory.

In 2004, VLT telescopes produced some of the first infrared images of extrasolar planets GQ Lupi b and 2M1207b. Among the more recent discoveries is the discovery of the farthest gamma-ray burst and the evidence for a black hole at the centre of our Galaxy, the Milky Way. The VLT has also discovered the candidate farthest galaxy ever seen by humans, Abell 1835 IR1916.>>

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[harry]

G'day

I was going to say an Irish joke, but! I forgot the joke.

Darn, its on the tip of my tongue.

I'LL be back.

[astrolabe]

Hello neufer,

Thank you, Good stuff!