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multi-immersion_objectives [2019/07/11 14:32]
jon [Location of Back Focal Plane]
multi-immersion_objectives [2019/10/14 13:24] (current)
jon [Location of Back Focal Plane]
Line 86: Line 86:
 ===== Location of Back Focal Plane ===== ===== Location of Back Focal Plane =====
  
-For some applications (e.g. light sheet illumination) it is important to maintain "​4f"​ spacing between optical elements, i.e. space adjacent lenses so that their focal planes line up.  If an external lens is positioned with focal position at this plane, parallel rays into the lens pair will emerge from the objective parallel. ​ Although the working distance does not depend on the refractive index of the medium, the location of the back focal plane does depend on it slightly. ​ Per optical simulations for the 54-10-12 objective lens, the location of the back focal plane referenced to flange is approximately 31.07 mm - 38.80 mm * RI + 9.42 mm * RI^2 (negative inside flange). ​ Specifically,​ this is ~4  mm inside the flange for water, ~5.4 mm inside the flange for FocusClear, and ~6.5 mm inside the flange for ethyl cinnamate (RI 1.56). ​ Per optical simulations for the 54-12-8 objective lens, the location of the back focal plane referenced to flange is approximately -11.75 mm - 22.90 mm * RI + 5.87 mm * RI^2 (negative inside flange). ​ Specifically,​ this is ~31.8  mm inside the flange for water, ~32.5 mm inside the flange for FocusClear, and ~33.2 mm inside the flange for ethyl cinnamate (RI 1.56). The difference in back focal plane between the two objectives depends on RI but is to a good approximation 27 mm deeper inside the objective for the 54-12-8 measured from the flange, or 5 mm deeper measured from the sample.+For some applications (e.g. light sheet illumination) it is important to maintain "​4f" ​or telecentric ​spacing between optical elements, i.e. space adjacent lenses so that their focal planes line up.  If an external lens is positioned with focal position at this plane, parallel rays into the lens pair will emerge from the objective parallel. ​ Although the working distance ​of these objectives ​does not depend on the refractive index of the medium, the location of the back focal plane does depend on it slightly. 
 + 
 +Per optical simulations for the 54-10-12 objective lens, the location of the back focal plane referenced to flange is approximately 31.07 mm - 38.80 mm * RI + 9.42 mm * RI^2 (negative inside flange). ​ Specifically,​ this is ~4  mm inside the flange for water, ~5.4 mm inside the flange for FocusClear, and ~6.5 mm inside the flange for ethyl cinnamate (RI 1.56). ​ Per optical simulations for the 54-12-8 objective lens, the location of the back focal plane referenced to flange is approximately -11.75 mm - 22.90 mm * RI + 5.87 mm * RI^2 (negative inside flange). ​ Specifically,​ this is ~31.8  mm inside the flange for water, ~32.5 mm inside the flange for FocusClear, and ~33.2 mm inside the flange for ethyl cinnamate (RI 1.56). The difference in back focal plane position ​between the two objectives depends on RIbut is to a good approximation ​the location is 27 mm deeper inside the objective for the 54-12-8 ​as measured from the flange, or 5 mm closer to the sample.
  
  
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multi-immersion_objectives.1562855533.txt.gz · Last modified: 2019/07/11 14:32 by jon