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--- howto:align_beam_backreflection [2022/08/29 10:58] – [Image on the beam diagnostics camera during focusing] peter
+++ howto:align_beam_backreflection [2022/08/29 11:02] – peter
@@ Line 10: / Line 10: @@
 {{:howto:backreflection_defocused1.mp4|}}
-The classic paper by E. Wolf "Electromagnetic Diffraction in Optical Systems. II." shows some 4 lobed patterns for polarized light.   http://rspa.royalsocietypublishing.org/content/253/1274/358
+Adding a drop of water on top of the coverslip reduces the back-scattering intensity by an order of magnitude or so, but the basic shape remains the same. Even if one removes everything extra from the beam path, these fringes remain there, they are universal. Note that all those images above are slightly defocused.
-These figures are also reproduced in his text book if you have access to that instead.   https://books.google.nl/books/about/Principles_of_Optics.html?id=aoX0gYLuENoC&hl=nl
-Adding a drop of water on top of the coverslip reduces the back-scattering intensity by an order of magnitude or so, but the basic shape remains the same. Even if one removes everything extra from the beam path, these fringes remain there, they are universal. Interferences are unavoidable, note that all those images reported above are slightly defocused.
 Such images are used for the daily and fundamental alignment of the MicroTime 200. The detailed procedure is described in the user manual of MicroTime 200. Although the MicroTime is extremely robust we suggest to spend 5-10 minutes every day for verifying the quality of the alignment by inspecting the back-reflection pattern. Have a look how this is used also by watching the tutorial [[howto:exchange_dichroic_mt200|How to exchange the main dichroic of the MicroTime 200.]]
+The classic paper by E. Wolf "Electromagnetic Diffraction in Optical Systems. II." shows some 4 lobed patterns for polarized light.  http://rspa.royalsocietypublishing.org/content/253/1274/358
+These figures are also reproduced in his text book if you have access to that instead.   https://books.google.nl/books/about/Principles_of_Optics.html?id=aoX0gYLuENoC&hl=nl