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Apertures, Stops, Pupils, and Windows; Single-Lens Camera

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Apertures, Stops, Pupils, and Windows; Single-Lens Camera Overview: composite optical elements ray from infinity bends at 2nd PP ray from then goes FFP BFP the FFP through the BFP FFL BFL FFP BFP bends at then goes EFL EFL 1st PP on to infinity 1st PP 2nd PP 1st PP 2nd PP 1st PP 2nd PP BFP image object FFP EFL EFL MIT 2.71/2.710 02/23/09 wk4-a- 1 1 Today • Apertures & Stops – Aperture – Entrance Pupil – Exit Pupil – Field Stop – Entrance Window – Exit Window MIT 2.71/2.710 02/23/09 wk4-a- 2 2 Aperture Stop and Numerical Aperture medium of refr. index n Aperture stop θ: half-angle subtended by the imaging the physical element which system from limits the angle of acceptance of the imaging an axial object system Numerical Aperture Speed pronounced f-number, e.g. f/8 means (f/#)=8. The Aperture Stop Later we will also learn that the NA also limits the optical energy defines the resolution (or resolving power) of that is admitted through the system the optical system MIT 2.71/2.710 02/23/09 wk4-a- 3 3 Entrance & exit pupils image through image through preceding elements succeeding elements entrance aperture exit pupil stop pupil multi-element optical system MIT 2.71/2.710 02/23/09 wk4-a- 4 4 The Chief & Marginal Rays M.R. C.R. Chief Ray: Starts from off-axis object, goes through the center of the Aperture Marginal Ray: Starts from off-axis object, goes through the edge of the Aperture Together, the C.R. and M.R. define the angular acceptance of spherical ray bundles originating from an off-axis object. MIT 2.71/2.710 02/23/09 wk4-a- 5 5 The Chief & Marginal Rays M.R. C.R. Corollaries: Chief Ray also goes through the center of the Entrance & Exit Pupils Marginal Ray also goes through the edge of the Entrance & Exit Pupils The Chief and Marginal Rays meet again at the image MIT 2.71/2.710 02/23/09 wk4-a- 6 6 The Field Stop Limits the angular acceptance of Chief Rays MIT 2.71/2.710 02/23/09 wk4-a- 7 7 The Field Stop FoV Defines the Field of View (FoV) MIT 2.71/2.710 02/23/09 wk4-a- 8 8 Entrance & Exit Windows image through image through preceding elements succeeding elements M.R. C.R. field stop exit entrance window window MIT 2.71/2.710 02/23/09 wk4-a- 9 9 All together M.R. C.R. field aperture entrance stop stop exit entrance pupil exit window window pupil MIT 2.71/2.710 02/23/09 wk4-a-10 10 All together C.R. FoV field aperture entrance stop stop exit entrance pupil exit window window pupil The Field of View is the angle between the pair of Chief Rays that just make it through the edges of the Field Stop MIT 2.71/2.710 02/23/09 wk4-a-11 11 All together NA field aperture entrance stop stop exit entrance pupil exit window window pupil The Numerical Aperture is the angle between the pair of Marginal Rays that just make it through the edges of the Aperture Stop MIT 2.71/2.710 02/23/09 wk4-a-12 12 Example: single-lens camera 2nd FP 1st FP size of film object plane or digital detector array image plane MIT 2.71/2.710 02/23/09 wk4-a-13 13 Example: single-lens camera 2nd FP 1st FP object plane Aperture Stop & Entrance Pupil image plane MIT 2.71/2.710 02/23/09 wk4-a-14 14 Example: single-lens camera 2nd FP 1st FP object plane Aperture Exit Stop pupil & Entrance (virtual) Pupil image plane MIT 2.71/2.710 02/23/09 wk4-a-15 15 Example: single-lens camera marginal ray chief ray 2nd FP 1st FP object plane Field Stop & Exit Window MIT 2.71/2.710 02/23/09 wk4-a-16 16 Example: single-lens camera chief ray 2nd FP 1st FP Field Stop Entrance & Exit Window Window MIT 2.71/2.710 02/23/09 wk4-a-17 17 Example: single-lens camera 2nd FP 1st FP Aperture Exit Stop pupil & Entrance (virtual) Pupil Field Stop Entrance & Exit Window Window MIT 2.71/2.710 02/23/09 wk4-a-18 18 Example: single-lens camera C.R. from object at field edge FoV nd M.R. from on-axis object 2 FP NA 1st FP Aperture Exit Stop pupil & Entrance (virtual) Pupil Field Stop Entrance & Exit Window Window MIT 2.71/2.710 02/23/09 wk4-a-19 19 Example: single-lens camera Lens, FL f MIT 2.71/2.710 02/23/09 wk4-a-20 20 Example: single-lens camera M.R. from object Lens, at field edge C.R. from object FL f at field edge M.R. from on-axis object FS ExP Aperture & ExW EnW & EnP MIT 2.71/2.710 02/23/09 wk4-a-21 21 MIT OpenCourseWare http://ocw.mit.edu 2.71 / 2.710 Optics Spring 2009 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms. .
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