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Imaging Spectrograph

At risk of entering a deep state of pedantic ranting this website explains our team’s semantic preference for arguing that lots of optical space flight instruments labeled spectrometers are better called "spectrographs".

See a few clarifications that would agree with our preference:

Early ground-based spectrographs for astronomy (e.g., developed by Henry J. Rowland at JHU) imaged a spectrum onto a photographic plate. Once spaceflight began and scanning monochrometers and Fourier Transform Spectrometer designs came into vogue the better term for them became spectrometers, since these scanned across wavelengths. At the onset of CCD based spectroscopy spaceflight instruments seemed to keep the name spectrometer rather than convert back to the more appropriate spectrograph for no better reason than familiarity and habit. Ground-based optical astronomy instruments are generally called spectrographs and never suffered the naming habit issue.

Wikipedia quotation:

“A spectrograph is an instrument that separates an incoming wave into a frequency spectrum. There are several kinds of machines referred to as spectrographs, depending on the precise nature of the waves. The first spectrographs used photographic paper as the detector. The star spectral classification and discovery of the main sequence, Hubble's law and the Hubble sequence were all made with spectrographs that used photographic paper. The plant pigment phytochrome was discovered using a spectrograph that used living plants as the detector. More recent spectrographs use electronic detectors, such as CCDs which can be used for both visible and UV light. The exact choice of detector depends on the wavelengths of light to be recorded.
A spectrograph is sometimes called polychromator, as an analogy to monochromator.”

SPIE quotation:

Spectrometer, Spectroscope, and Spectrograph

Excerpt from Field Guide to Spectroscopy

A spectrometer is any instrument used to probe a property of light as a function of its portion of the electromagnetic spectrum, typically its wavelength, frequency, or energy. The property being measured is usually intensity of light, but other variables like polarization can also be measured. Technically, a spectrometer can function over any range of light, but most operate in a particular region of the electromagnetic spectrum.

A spectroscope is a device that measures the spectrum of light. Early versions had a slit, a prism, and a screen with markings to indicate various wavelengths or frequencies; later versions were calibrated to electronic detectors. Although the apparatus Isaac Newton used in his work on the spectrum of light can be considered a crude spectroscope, it is generally recognized that the spectroscope was invented by Gustav Kirchhoff and Robert Bunsen around 1860.

A spectrograph is an instrument that separates incoming light by its wavelength or frequency and records the resulting spectrum in some kind of multichannel detector, like a photographic plate. Many astronomical observations use telescopes as, essentially, spectrographs.