Reflection telescopes

Slides Of reflecting telescopes, aeroplanes, space capsules, bicycles (to illustrate applications of stiff but light materials). 

Through a curious set of circumstances, Newton failed to solve the problem of chromatic aberration, and so, he abandoned the attempt to construct a refracting telescope which should be achromatic, and instead designed a reflecting telescope, probably on the model of a small one that he had constructed in 1668. The form he used is known by his name today. 

The poor reflectivity of speculum and the tighter figure tolerance, combined with the difficulty to accurately measure aspherical surfaces have slowed the evolution of the reflecting telescope down. These issues are of a pure technological nature optical solutions for reflecting telescopes were derived in the... 

Figure 8. Marin Mersenne s designs of all-reflecting telescopes, 1636.

Reflecting telescopes would, however, still compete with refracting ones, mostly for their feasibility in much larger diameters. Herschel s telescopes,... 

Torricelli makes the first barometer using mercury in a sealed glass tube The Dutch scientist Anton van Leeuwenhoek develops a microscope Isaac Newton invents a reflecting telescope... 

Astronomer George Ellery Hale (1868-1938), educated at MIT, founded Mt. Wilson observatory, 1904, and designed the two-hundred inch (five m) reflecting telescope for Mt. Palomar observatory. 

Sir Isaac Newton was dissatisfied with the limitations of Galileo s refracting telescope, which operates like a spyglass, and he invented the reflecting telescope. 

Modem reflecting telescopes range in size from small amateur instruments to the great Palomar telescope with its mirror measuring 200 inches across, but the principle is the same. Parallel rays of light from the stars are reflected to a single focal point by a parabolic mirror. 

The method widely used for silvering the mirrors of astronomical reflecting telescopes and other optical parts is a modification... 

Optical astronomical telescopes fall into two main classes refracting telescopes (or refractors), which use lenses to form the primary image, and reflecting telescopes (or reflectors), which use mirrors. 

The concept behind optical devices which incorporate liquids as a fundamental part of the optical structure can be traced at least as far back as the eighteenth century where rotating pools of mercury were proposed as a simple technique to create smooth spherical mirrors for use in reflecting telescopes. Modem microfluidics has enabled the development of a present-day equivalent of such devices, the development of which we now refer to as optofluidics. As will be described below, the capabilities in terms of fluidic control, mixing, miniaturization, and optical property tuning afforded by micro-, nano-, and electro-fluidics combined with soft lithography-based fabrication provide an ideal platform upon which to build such devices. 

Silver nanoparticles were also used to improve the detection of liquid solutions of analytes at a target-collector distance of 7 m. The experimental setup of the prototype instrument used to perform standoff Raman detection is schematically shown in Figure 8. The prototype system consists of an Andor Technologies Shamrock spectrograph equipped with a charge-coupled device detector (CCD), a reflecting telescope, a fiber optic bundle cable, a notch (or edge) filter assembly and a laser source (532 and 488 nm) for active standoff Raman detection. 

Figure 1 shows in schematic detail an idealized reflective telescope for aerospace applications. The focal plane is a cryo-genically cooled series of photo-optical sensors operating below 100 K. The walls and baffles of the system also must operate in that temperature region to prevent their becoming extraneous inputs to the sensor system. The restraints this puts on the materials of construction and how these problems are met are the subject of this section. 

The devices made by Lippershey and Galileo were both refractor telescopes, which rely primarily on lenses that gather and focus light. In the second half of the seventeenth century, English physicist Isaac Newton was among the early pioneers of the reflecting telescope, which relies primarily on curved mirrors that bend light. 

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