That is called a Cassegrain. The main mirror is a paraboloid which focusses the light from a star down to a point, then the secondary small mirror is a hyperboloid with one focus that coincides with the focus of the main mirror, and the other focus is behind the main mirror, where the eyepiece is.
This arrangement is common in radio telescopes as a way of reducing radio noise picked up from the 'hot' ground which is at approximately 260 degrees Kelvin or more.
A reflecting telescope only needs one mirror, the primary mirror which will focus incoming light to a single point. A digital telescope might place the digital recording media directly in front of the reflecting telescope without any additional mirrors (although perhaps some lenses). For practical purposes though, most optical telescope will have a secondary mirror that will either focus light straight back through a hole in the primary telescope mirror, or to the side of the telescope. Some telescopes, especially the large ones in observatories will have several mirrors directing the light path to the observer or recording equipment.
The Hubble telescope was a basic reflector telescope with a 94.5 ft mirror. The Hubble collects light though its open end, the primary mirror reflects the light to a secondary mirror that then reflects the light through a hole in the primary mirror to a focal point of the instruments or eyes of the Hubble.
It is called a Cassegrain. The small convex subreflector is a hyperboloid with one focus at the focus of the main mirror, and the other focus just behind the main mirror where the eyepiece is.
It is a paraboloid, which focusses the light from a star down to a single point which can then be looked at through the eye lens or eyepiece.
A reflecting telescope is an optical telescope which uses mirrors to bring the light to a focus. The first one was designed by Isaac newton.
are you doing your science homework?
A reflecting telescope only needs one mirror, the primary mirror which will focus incoming light to a single point. A digital telescope might place the digital recording media directly in front of the reflecting telescope without any additional mirrors (although perhaps some lenses). For practical purposes though, most optical telescope will have a secondary mirror that will either focus light straight back through a hole in the primary telescope mirror, or to the side of the telescope. Some telescopes, especially the large ones in observatories will have several mirrors directing the light path to the observer or recording equipment.
The Hubble telescope was a basic reflector telescope with a 94.5 ft mirror. The Hubble collects light though its open end, the primary mirror reflects the light to a secondary mirror that then reflects the light through a hole in the primary mirror to a focal point of the instruments or eyes of the Hubble.
It is called a Cassegrain. The small convex subreflector is a hyperboloid with one focus at the focus of the main mirror, and the other focus just behind the main mirror where the eyepiece is.
It is a paraboloid, which focusses the light from a star down to a single point which can then be looked at through the eye lens or eyepiece.
An optical telescope (as distinct from, say, a radio telescope). It's possible that the answer was intended to be "a refracting telescope" but reflecting telescopes use lenses as well.
-- A refracting telescope must have a lens, otherwise it's not a refracting telescope. -- A reflecting telescope can be constructed without any lens, but if you intend to look through it, then you'll use a little lens for the eyepiece.
A reflecting telescope is an optical telescope which uses mirrors to bring the light to a focus. The first one was designed by Isaac newton.
A reflecting telescope has both magnifying mirrors and lenses to focus the image on the eyepiece. A refracting telescope uses only lenses to magnify and focus. A reflecting telescope can be much smaller, because the light can travel through the barrel of the telescope several times, being magnified with each reflection. This is why most large modern telescopes are reflectors.
Refracting telescope: Brings light to a focus by passing it completely through a transparent glass lens.The lens must be perfect throughout, and unobstructed.Reflecting telescope: Brings light to a focus by reflecting it from the surface of a curved mirror.The surface shape must be perfect, but the mirror may be made of anything, and can be supportedby anything.
Primary means "first" and secondary means "second". When something is of primary importance, it is the most important thing. When something is of secondary importance, it is important, but not the most important thing. Primary school is first grade through eighth grade; secondary school is ninth grade through twelfth grade. Primary school comes first and secondary school comes next.
Newton did not invent the telescope. The first practical telescope was made by Hans Lippeshey and Zacharias Janssen in 1608 in the Netherlands. Galileo made significant improvements the following year. All these early refracting telescopes suffered from big problems with chromatic aberation, the separation of colours.The first reflecting telescope is credited to Niccolò Zucchi in 1616. In 1668, Isaac Newton invented a much improved reflecting telescope that still bears his name, the "Newtonian reflector." He added a smaller "diagonal" mirror near the primary mirror's focus to reflect the image at a 90° angle allowing him to look through the side of the telescope and see without blocking the incoming light.Nice answer upstairs! Newton made his first "good" reflecting telescope in 1688. It still exists -- and works!