Spectrohelioscope
Encyclopedia
A spectrohelioscope is a type of solar telescope
designed by George Ellery Hale in 1924 to allow the Sun to be viewed in a selected wavelength
of light. The name comes from three Latin-based words: Spectro, referring to the optical spectrum, Helio, referring to the Sun and Scope, as in telescope.
The basic spectrohelioscope is a complex machine that uses a spectroscope to scan the surface of the sun. The image from the objective lens is focused on a narrow slit revealing only a thin portion of the suns surface. The light is then passed through a prism
or diffraction grating
to spread the light into a spectrum. The spectrum is then focused on another slit that allows only a narrow part of the spectrum (the desired wavelength of light for viewing) to pass. The light is finally focused on an eyepiece so the surface of the Sun can be seen. The view, however, would be only a narrow strip of the Sun's surface. The slits are moved in unison to scan across the whole surface of the sun giving a full image. Independently nodding mirrors can be used instead of moving slits to produce the same scan: the first mirror selects a slice of the sun, the second selects the desired wavelength.
The Spectroheliograph
is a similar device, but images the sun at a particular wavelength photographically and is still in use in professional observatories.
Solar telescope
A solar telescope is a special purpose telescope used to observe the Sun. Solar telescopes usually detect light with wavelengths in, or not far outside, the visible spectrum.-Professional solar telescopes:...
designed by George Ellery Hale in 1924 to allow the Sun to be viewed in a selected wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
of light. The name comes from three Latin-based words: Spectro, referring to the optical spectrum, Helio, referring to the Sun and Scope, as in telescope.
The basic spectrohelioscope is a complex machine that uses a spectroscope to scan the surface of the sun. The image from the objective lens is focused on a narrow slit revealing only a thin portion of the suns surface. The light is then passed through a prism
Prism (optics)
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...
or diffraction grating
Diffraction grating
In optics, a diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams travelling in different directions. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as...
to spread the light into a spectrum. The spectrum is then focused on another slit that allows only a narrow part of the spectrum (the desired wavelength of light for viewing) to pass. The light is finally focused on an eyepiece so the surface of the Sun can be seen. The view, however, would be only a narrow strip of the Sun's surface. The slits are moved in unison to scan across the whole surface of the sun giving a full image. Independently nodding mirrors can be used instead of moving slits to produce the same scan: the first mirror selects a slice of the sun, the second selects the desired wavelength.
The Spectroheliograph
Spectroheliograph
The spectroheliograph is an instrument used in astronomy. It captures a photographic image of the Sun at a single wavelength of light, a monochromatic image...
is a similar device, but images the sun at a particular wavelength photographically and is still in use in professional observatories.