Re: Eyepiece and virtual image
Posted by
Guy Cox on
URL: http://confocal-microscopy-list.275.s1.nabble.com/PSF-with-DIC-tp3781952p3787121.html
Re: Eyepiece and virtual image
But is this image truly in focus? If you adjust the
microscope focus, does it get sharper?
Guy
Dear Guy,
The point is that I neither adjust the
focus nor lift the eyepiece. I look through the eyepiece (without my glasses, I
am short-sighted), focusing and then I only hold a piece of paper in front of
the eyepiece and can see the picture on it. And this also happens to
my normal-sighted colleagues.
Joachim
On [DATE], "Guy Cox"
<[ADDRESS]> wrote:
You can always get a real image from an eyepiece by refocussing so
that the first image is in front of the focal plane of the eyepiece - either
adjust the microscope focus a little or lift the eyepiece slightly in its
tube. If you see a sharp image without refocussing from your normal
viewing position, it probably means that you - like me - are
long-sighted!
Guy
Optical Imaging
Techniques in Cell Biology
by Guy Cox CRC Press / Taylor
& Francis
http://www.guycox.com/optical.htm
______________________________________________
Associate
Professor Guy Cox, MA, DPhil(Oxon)
Electron Microscope Unit, Madsen
Building F09,
University of Sydney, NSW
2006
______________________________________________
Phone +61 2 9351
3176 Fax +61 2 9351 7682
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From: Confocal
Microscopy List [[hidden email]]
On Behalf Of Joachim Hehl
Sent: Thursday, 8 October 2009 7:36
PM
To: CONFOCALMICROSCOPY@...
Subject:
Eyepiece and virtual image
Dear all,
I
have a maybe stupid- and not confocal but basic optic question:
As
you can read in all textbooks concerning microscopy and geometric optics the
objective produces a real, inverted and magnified image since the distance
from the object to the object front lens is bigger than one but less than two
focal lengths of that given objective.
This intermediate image is then
magnified by the eyepiece. Since the intermediate image lies exactly in
the front focal plane of the eyepiece the result is a virtual, true sided and
magnified image which occur in the infinite space. Our eye with its
optical components is then producing a real image on the retina.
So far, so
good.
By definition, a virtual image can not be captured on a screen. BUT:
When I hold a piece of paper in front of the eyepiece in a distance bigger or
smaller than the back focal plane of the eyepiece (the distance I use
when I look through it with my eyes) I am able to capture a pretty sharp image
of my object on the paper. Why is this? I should not since it is a virtual
image?
Thanks for your input!
Joachim
Joachim
Hehl
LMC-Light Microscopy Centre, ETH Zurich
Hönggerberg
Schafmattstrasse 18, HPM F16.1
CH-8093, Zurich,
Switzerland
Web: www.lmc.ethz.ch
Phone: +41
44 633 6202
Natel: +41 44 658 1679
Fax:
+41 44 632 1298
e-mail: Joachim.Hehl@...