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Glossary
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of
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Light
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Microscopy
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Terms
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Binning
Binning is a process used to increase the sensitivity of a CCD camera by combining the charge from adjacent pixels to boost the signal-to-noise
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ratio
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in
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the
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image.
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If
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we
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imagine
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a
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hypothetical
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camera
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(see
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below)
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with
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a
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chip
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consisting
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of
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4x4
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pixels
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and
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we
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apply
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a
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binning
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factor
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of
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2x
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then
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2x2
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arrays
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of
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adjacent
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pixels
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will
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be
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combined
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together
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to
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form
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an
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array
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of
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'super
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pixels'
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that
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are
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four
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times
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the
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area
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of
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the
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originals
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and
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contain
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the
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combined
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charges
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of
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the
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adjacent
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pixels.
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This
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improves
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the
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signal-to-noise
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ratio
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because
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CCD
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camera
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readout
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noise
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often
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obscures
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low
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signals.
...
If
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the
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readout
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noise
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of
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the
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hypothetical
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camera
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below
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is
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25
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grey
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levels
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then
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most
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of
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the
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signals
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in
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the
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image
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on
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the
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left
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will
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be
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indistinguishable
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from
...
noise.
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By
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combining
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the
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charges
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from
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adjacent
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pixels
...
the
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readout
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noise
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threshold
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is
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easily
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exceeded
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in
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most
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of
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the
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pixels
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in
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the
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image
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on
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the
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right.
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Image acquisition is also faster for binned images because the readout time is shorter and the exposure time is usually shorter too. The drawback of using binning is that the resolution is lower because the specimen is now being sampled by fewer pixels. For example, a specimen imaged with the hypothetical camera above in 2x binning mode would be sampled by four large pixels instead of 16 small ones. The images below broadly illustrate the effect of increasing binning factors on resolution. At high binning factors pronounced pixelation is seen in the images when all are magnified to the same dimensions. 
What does binning mean? (Andor Technologies)
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Long Working Distance (LWD) objective lenses
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{float:right}
!collar1.jpg|border=1!
{float}
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Most
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biological
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objective
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lenses
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are
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designed
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to
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focus
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on
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specimens
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mounted
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under
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a
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standard
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#1.5
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coverslip,
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which
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is
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about
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170
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µm
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thick.
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Most
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of
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these
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objectives
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cannot
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focus
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through
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the
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plastic
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in
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the
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bottom
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of
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a
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standard
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microtitre
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plate
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because
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their
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working
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distances
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are
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only
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a
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few
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hundred
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µm
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and
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the
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bottom
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of
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the
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plate
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is
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in
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the
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order
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of
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1
...
mm
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thick.
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Long
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working
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distance
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objectives
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are
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designed
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to
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focus
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on
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specimens
...
relatively
...
far
...
away
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from
...
the
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front
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lens
...
and
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can
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cope
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with
...
the
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thickness
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of
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a
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microtitre
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plate.
...
Many
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LWD
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objectives
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have
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correction
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collars
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that
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can
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be
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adjusted
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for
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a
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variety
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of
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specimen
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thicknesses.
...
If
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a
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collar
...
has
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been
...
adjusted
...
for
...
a
...
1
...
mm
...
thickness
...
(e.g.
...
the
...
bottom
...
of
...
a
...
plastic
...
dish)
...
it
...
will
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not
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focus
...
correctly
...
through
...
a
...
glass
...
coverslip
...
and
...
you
...
will
...
need
...
to
...
adjust
...
the
...
collar
...
to
...
a
...
setting
...
appropriate
...
to
...
a
...
170
...
micron
...
thickness.
...
There
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is
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no
...
systematic
...
way
...
of
...
adjusting
...
correction
...
collars.
...
The
...
best
...
way
...
is
...
to
...
set
...
the
...
collar
...
to
...
approximately
...
the
...
correct
...
position
...
before
...
observing
...
your
...
sample,
...
then
...
to
...
focus
...
on
...
the
...
sample,
...
and
...
finally
...
to
...
make
...
fine
...
adjustments
...
to
...
the
...
collar
...
position
...
if
...
necessary.
...
The
...
adjacent
...
picture
...
shows
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the
...
correction
...
collar
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of
...
a
...
Leica
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objective
...
lens
...
when
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adjusted
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for
...
a
...
1
...
mm
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sample
...
thickness.
...
The
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black
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dot
...
marks
...
the
...
position
...
of
...
the
...
collar
...
and
...
the
...
numbers
...
around
...
the
...
objective
...
barrel
...
indicate
...
the
...
thickness
...
for
...
which
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the
...
lens
...
will
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be
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adjusted.
...
The
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knurled
...
ring
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above
...
the
...
dot
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should
...
be
...
used
...
to
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rotate
...
the
...
collar.
...
Unfortunately
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the
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Leica
...
objectives
...
don't
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have
...
a
...
mark
...
for
...
the
...
position
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for
...
a
...
170
...
micron
...
coverslip,
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so
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the
...
correct
...
position
...
can
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only
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be
...
set
...
approximately.
...
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Numerical Aperture (NA)
...
The
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numerical
...
aperture
...
is
...
a
...
dimensionless
...
value
...
that
...
characterises
...
the
...
resolution
...
of
...
a
...
lens.
...
It
...
is
...
defined
...
by
...
the
...
following
...
equation:
...
NA
...
=
...
n
...
sinθ
...
Where
...
n
...
is
...
the
...
refractive
...
index
...
of
...
the
...
immersion
...
medium
...
and
...
θ
...
is
...
the
...
half-angle
...
of
...
acceptance
...
of
...
the
...
lens.
...
The
...
higher
...
the
...
NA
...
the
...
higher
...
the
...
resolution
...
of
...
the
...
lens.
...
The
...
NA
...
cannot
...
exceed
...
the
...
refractive
...
index
...
of
...
the
...
immersion
...
medium,
...
so
...
lenses
...
for
...
use
...
in
...
standard
...
immersion
...
oils
...
(
...
n
...
≈
...
1.51)
...
tend
...
to
...
have
...
a
...
maximum
...
NA
...
of
...
1.4
...
to
...
1.45
...
Links:
...
...
...
...
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Working Distance (WD)
The working distance is the distance from the front of the lens to the nearest surface of the coverslip when the specimen is in sharp focus. For objective lenses designed for use without a coverslip the surface of the culture vessel or specimen in used.
Links: