Sources
There are many sources of stray light. For example:
- Ghost orders in diffraction gratings. These can be caused by periodic variations in the spacing of grooves in ruled gratings, for instance.
- Light scattered towards a telescope from particles along the optical path to a star.
- Light emitted by components of the optical system.
- Infrared optical systems are, obviously, especially susceptible due to thermal radiation.
- Reflections from lens surfaces.
- Anti-reflective coatings are used to reduce stray light.
- Narcissus - Specifically, thermal radiation from the infrared detector reflected back to itself from lens surfaces.
- Light scattered from the surfaces of supporting structures within the optical system.
- Diffuse reflection from imperfect mirror surfaces.
- Light leaks in the enclosure of the system.
- This might be the first cause to come to mind, but as this list shows, it is hardly the only source of stray light.
Read more about this topic: Stray Light
Famous quotes containing the word sources:
“The sources of poetry are in the spirit seeking completeness.”
—Muriel Rukeyser (1913–1980)
“Even healthy families need outside sources of moral guidance to keep those tensions from imploding—and this means, among other things, a public philosophy of gender equality and concern for child welfare. When instead the larger culture aggrandizes wife beaters, degrades women or nods approvingly at child slappers, the family gets a little more dangerous for everyone, and so, inevitably, does the larger world.”
—Barbara Ehrenreich (20th century)
“My profession brought me in contact with various minds. Earnest, serious discussion on the condition of woman enlivened my business room; failures of banks, no dividends from railroads, defalcations of all kinds, public and private, widows and orphans and unmarried women beggared by the dishonesty, or the mismanagement of men, were fruitful sources of conversation; confidence in man as a protector was evidently losing ground, and women were beginning to see that they must protect themselves.”
—Harriot K. Hunt (1805–1875)