Field lens

In imaging optics, a field lens is a positive-powered lens or group of lenses that comes after the objective lens and before the image plane or the eyepiece, serving to change the size of the image[1][2] or to provide image-space telecentricity. It is used for the reduction of detector size and, in instances needing high optical gain factor, it can correct aberrations through its several elements.[3] Optical systems that feature multiple image planes are at risk of a potential problem, which involves the inability on the part of succeeding relay lenses to capture a cone of light from the primary objective lens.[4] The field lens - by behaving as a variably angled lens - solves this problem by bending or refracting the cone of light back into the succeeding relay lens.

In X-Ray microscopy, the field lens is used to produce parallel and homogeneous illumination of the stencil.[5]

References
  1. Judah Levine, University of Colorado Physics 1230: Light and Color: The Field Lens. Fall 2001
  2. SPIE Optopedia: Field Lens
  3. Riedl, Max (2001). Optical Design Fundamentals for Infrared Systems. Bellingham, Washington: SPIE Press. p. 34. ISBN 0819440515.
  4. Igel, Eugene; Kristiansen, Magne (1997). Rotating Mirror Streak and Framing Cameras. Bellingham, Washington: SPIE Optical Engineering Press. p. 1. ISBN 0819424617.
  5. Schmahl, G.; Rudolph, D. (1984). X-Ray Microscopy: Proceedings of the International Symposium, Göttingen, Fed. Rep. of Germany, September 14–16, 1983. Berlin: Springer-Verlag. p. 120. ISBN 9783662135471.
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