Cleaning optics
For technicians!
This chapter describes used materials,
tools, techniques and procedures to cleaning mirror surfaces, lenses and other
optics components; used in Pannoramic scanners. If dust or fingerprints are the
reason for the unwanted appearance in the view, the optical component has to be
found on which the contamination is situated on. Therefore, a procedure is
added also to determine which optical component may contain the contamination.
Contents
To clean optical surfaces includes always
the risk of scratching or other kind of damaging the optics or to make it
unusable; therefore cleaning of optics to be on the safe side is not
recommended!
On the other side, dirt, grease,
fingerprints or dust may reduce the quality of the virtual tissue drastically;
so, to increase the quality of the virtual tissue, cleaning of the appropriate
optical part might be unavoidable. Furthermore, different kind of contamination
(dust, fingerprint, grease) might need different tools or procedures to remove
them.
Important
Never use pressure on the optics surface; never rub
to remove contaminations from optical surfaces!
· If you are not sure, whether to clean an
optical surface or not, do not proceed! All
these things are reasons to avoid cleaning of optics;
·
The
best way, to avoid cleaning of optics, is prevention.
Important
3DHISTECH accepts no
liability under any circumstances for damage of optics, optical parts or
optical surfaces during the cleaning procedure performed by the user!
The use of the following
information, described procedures and used materials is exclusively at the risk
of the user!
The
following recommended materials and procedures are tested and the optics was
free of contamination after cleaning; but persistent dust or dirt had not to be
removed until now.
The best way to avoid cleaning of the optics is the
use of the scanner in dust free surroundings and to protect the entire scanner
with a dust protecting mantle if the scanner is not in use.
Precautions to avoid cleaning of optical
components
·
Never
touch optical surfaces with fingers or not recommended tools; touch always the
mounting only.
·
Never
leave the lenses or mirrors, dust cups or units, that including optical
components (e.g. cameras or camera adapters), uncovered in the room; optical
surfaces should be protected and covered always immediately by the use of dust
cups, plastic bags or elsewhere, if they are even not in use or stored.
·
Check
dust cups and other dust protecting means of cleanness. If these means are
dusty, the dust may be easily transmitted onto the surface to be protected.
Warning!
·
Never
use any aerosol spray products to remove dust from optics.
·
Never
use paper handkerchiefs; these SCRATCH the optics.
·
Never
use “beauty” cotton balls or pads; they are frequently contaminated by other
materials.
·
Never
use mains water or ion exchanged water (often used for batteries). If water
should be used to clean optics, use only distilled water.
·
Never
use any cleaning materials, made by common known “household” companies, for
optics.
To reduce the danger of contamination of
the cleaning materials and tools with dust, use a cleanable plastic box to
protect and store them; furthermore, leave all the tools and unused materials
in their original package until use. After the cleaning procedure is finished,
return the tools and materials into the plastic box. Used one way materials
have to be disposed. Materials like finger coats, cleaning tissues and cotton
balls or pads are one way products; cleaning tissues and cotton pads have to be
used for one wipe only. During the cleaning procedure never use pressure; do
not press the cleaning materials onto the optics surface to be cleaned. The
weight of the cleaning material itself is often enough and defines the force
onto the surface.
If you are using other materials or
solutions, check the materials of consisting unwanted components, cleanness and
lint-freeness; check the procedures also of scratch freeness. Sterile packed
100% cotton materials, used in the medicine or for surgeries can be used almost
unhesitatingly, but check them of lint-freeness.
By using a manual air blower, loosen dust
can be removed easily.
Do not use
canned air cleaner products for optics; the composition is often not exactly
known and may contain contaminations; these may damage the optics surface or
the coating. Furthermore, if a powerful air blow reaches the optics surface,
the existing dust particles on the optics may scratch the surface or coating
immediately!
To
grip and hold lens cleaning tissues or cotton pads a clamp forceps is very
helpful.
Any
kind of cleaning materials like cotton batting, cleaning tissues or cotton pads
can also be hold by a plastic tweezers.
·
The
cotton material to be hold should fully cover the peaks of the tweezers and
should keep a thick coating to prevent touching the surface with the peaks.
To
clean lens surfaces or to remove lint, special lens brushes can be used. The
use of the lens brush for mirror surfaces is not recommended. The lens brush
should be cleaned or replaced from time to time, because the dust will adhere
to the hairs of the brush.
Latex
finger coats
To
protect optics from fingerprints during execution of the cleaning procedure,
finger coats are used; even so, used materials will not be contaminated if they
are touched. Latex gloves may also be used.
The liquid, used to clean optical surfaces
can be dosed excellent by a bottle dropper.
The used liquid is 96% - 98% ethanol or
methanol; available in any pharmacy, the bottle dropper also.
High concentrated ethanol or methanol is very
hygroscopic. After some drops of liquid is dropped onto the cleaning material,
close the bottle immediately, never leave the bottle unclosed.
To avoid contamination of the
cleaning liquid, the pipette should never touch the material where the liquid
is dropped on.
Take into account that such liquids are
very flammable. The quantity in stock of the liquid for such cleaning projects
must not exceed 1l; otherwise special fire prevention measures have to be
taken!
Cotton batting
For some optical surfaces, like the
objective lenses, a very thin tool with cotton batting is used for the cleaning
procedure; the cotton batting should be 100% cotton with long fibers if
possible. Long fibers reduce the probability of remaining lint on the lens
surface.
Wooden or bamboo tools
To reach the lens surface of the objective
on the tissue side, a peak ended wooden tool was created; to clean the lens
surface on the camera side a flat ended tool can be used.
The tool was created from a small, low
priced paint brush. After removing the brush part, the remaining stick was
prepared as shown. A roughened surface of the tool ends increases the adherence
of the cotton.
· To create bamboo tools, Asian chopsticks
are very well suited as basic material.
·
Wrap
an amount of cotton (depending on the size of the area to be cleaned) over the
peak or the flat ended part of the tool.
· The end of the tool has
to be fully coated by cotton.
Such
lens cleaning tissues do not scratch the optics surfaces; it can be used for
mirrors and lenses both; nevertheless, each surface of the tissue can be used
for one wipe only!
Because
the size of one of these pads is large (100x90 mm), and large pads are seldom
needed, it can be cut in halves, quarters or strips.
These
pads are often used to remove dust from borders of the lens or edges of
mirrors. The surface of the pad can be used also only for one wipe.
Magnifier (with lamp)
To find the dust particles or fingerprints
on the optical surface a magnifier lamp with a magnification of at least 6
times is recommended; the type is unimportant.
·
In
practice, any kind of appropriate magnifier can be used also.
Find the dirty
component
Decide, where the dust
can be found
It happens, that the result of the scan process shows unwanted effects;
the reason may be dust, fingerprints, or unwanted illumination effects.
If dirt is the reason for the unwanted
appearance, it is important to decide, on which component(s) the dust or dirt
is situated on.
First, check the scan quality with different slides and tissues; analyze
and compare the scanned results carefully. For this purposes, clean the cover
slip top and the slide bottom surface before the slide will be scanned. Decide
in which part the dirt may be found; in the image path or in the illumination
path. In the image path the contour of the dirt is shown often not in focus and
on each FOV, always on the same place; while in the illumination path the dirt
creates darker spots, also always at the same place of each FOV.
·
If
dust or fingerprints are on the cover slip, you often have difficulties with
focusing, the focus position can be found on the dust and not on the surface of
the sample; so often “FOV’s out of focus” are produced in the virtual tissue.
The clean FOV
“Clean” FOV means
that the observed area of the slide, covered with the cover slip, seen by the
scan camera with 1 exposure, is free of tissue and dirt. If the live view is
changed to another slide position, and the dirt does not move, the optical path
is contaminated with dirt.
On the other side, if the scanned tissue shows the same occurrences,
always on the same position of the scanned field of view, the check for
cleanness of the illumination and image path should be performed in the live
view with a clean field of view.
This will be used during detecting the
dirty surface also. By checking the clean FOV, the kind of the observed
occurrence should be the same as in the scanned tissue. Try also with different
clean FOVs.
For more information about the mechanical
construction and adjustment procedures of the optics and the brightfield
illumination see the chapter “Optics and
brightfield illumination”.
The
contamination of the image path can be situated on
·
The cover glass of the
camera’s CCD.
·
Both
sides of the camera adapter’s
lens, if the magnification differs from 1.0x.
·
Both
sides of the tube lens.
·
Both
sides of the objective.
·
The
top of the cover slip.
Dust or dirt on parts of the brightfield
illumination may be found on
·
The
surface of the slide on illumination side.
·
Both
surfaces of the condenser.
·
The
surface of the
illumination mirror.
·
Both
surfaces of the diffuser.
·
Both
surfaces of the aspheric lens.
·
The
surface of the illumination source.
If the contamination is found inside the
tissue, it means, between cover slip and slide, the quality of this virtual
tissue can not be increased; and this may be also a reason for parts out of
focus in the virtual tissue! Check this behavior first before starting any
cleaning of components!
1. Clean
the slide bottom and the cover slip top
This procedure is done easily, because
these surfaces are not coated. Nevertheless do not scratch the surfaces!
· The scratched cover slip results in focusing
difficulties as described for dust;
·
The
scratched slide surface results in difficulties with the illumination.
1.
With
the manual air blower remove loosen dust and check the surfaces with a
magnifier.
2. To remove fingerprints and grease, use
some drops of ethanol on a cotton towel or a cotton pad and wipe the surfaces
carefully as necessary.
2. Find the contaminated
surface in the image path
By
rotating the components of the image path separately, the dirty or dusty
component can be found.
The best is starting with the CCD surface and going
into the direction to the cover slip. After cleaning any part, the entire
optical path should be checked again; see also “Optics and brightfield illumination”; “Check the
optical adjustments”.
Rotate
the camera a little bit on the mounting to the
camera adapter and observe the live view. If the dust or spot does not move, the cover glass of the cameras
CCD should be cleaned.
If the dirt moves in the live view so as
you are changing the camera rotation angle, the dirt is not found on the CCD
cover glass of the camera; proceed with the next step.
Rotate the camera adapter. Hold the camera tube and the scan camera in constant position to each
other and rotate only the
camera adapter. If the dust or spot moves, the camera adapter lens has to
be cleaned.
After dismounting the camera adapter, use
a magnifier to see and find the contamination on the surface of the lens; blow
away loosen dust first before cleaning the appropriate surface.
Rotate the
camera tube. Loosen the camera tube clamp and the
camera adapter (not the tube mounting bolts!); then hold the camera adapter and
the scan camera in constant position to each other and rotate only the camera
tube. If the dust or spot moves, the camera tube lens has to be cleaned.
After dismounting the camera tube, use a
magnifier to see the contamination on the surface of the lens; clean the
appropriate surface, see also “to clean the camera tube lens”.
Rotate the objective. If the dust or spot moves, the objective lens has to be cleaned.
After dismounting the objective, use a
magnifier to see the contamination on the surface of the lens; clean the
appropriate surface, see also “to clean the objective”.
3. Find the dirty
component in the illumination path
This task is more complicated, because an
adequate routine like described for the image path can not be made. If you
think, that there will be a contamination in the illumination path, each
component has to be checked separately by using the magnifier. Preventive
cleaning of the illumination source (the halogen lamp) and the diffuser can be
done, because these components are not surface coated.
· The illumination path may be dirty if the
dust is always visible (nearly in focus) over the entire focus range.
Precautions; mainly if
dust free surroundings are not given
· Switch off air conditions, fans and other
air blowing equipments; close doors and windows.
·
Clean
the surrounding and the table where the optics should be cleaned. To avoid dust
clouds in the air, use a wet (moistened) towel for cleaning.
·
Use a
clean, lint-free cotton towel as a working surface; this can avoid scratching
the surfaces if the mirror or lens may perhaps fall out of your fingers.
·
Remove
the optical component to be cleaned from the scanner and place it onto the work
area.
·
Wash
your hands before starting the cleaning procedure; so dust and grease will be
removed from your fingers and can not occur on the finger coats or cleaning
tools.
·
Arrange
the tools and utilities on the table so, that these can be reached by your
hands easily but the direct working surface should be left free.
·
Never
dry-up liquid cleaned optical surfaces with a fan or hair-dryer after cleaning;
dust will be blown onto the surface again! Do not blow air with your mouth onto
the optical surface!
·
Never
do the cleaning procedure in hurry, be always carefully and foresighted and
exercise patience; the success needs time.
·
Pull
the latex finger coats over thumb, forefinger and middle finger of both hands
before you touch the optics.
Blowing away dust from
“sunk-in” surfaces
·
Often optical surfaces like lenses or
cover glasses are mounted with a “sunk-in” solution to protect them against
scratching; this makes it more difficult to clean them.
·
Blow
with the manual air blower
from different directions more times the surface of the lens, so lint and loosen
dust particles can be removed from the edge of the lens also.
·
Check
the result with the magnifier.
·
Repeat
the procedure if necessary.
Blowing away dust from
plane surfaces
·
Blow with the manual air blower from
different directions more times the surface of the mirror, so lint and loosen
dust particles can be removed from the edge of the mirror also.
·
Check
the result with the magnifier.
·
Repeat
the procedure if necessary.
Create the tool for cleaning plane
surfaces with liquid
· 
Take a lens cleaning tissue and fold it in
the middle of the shorter edge, if the mirror or the plane surface to be
cleaned is small.
·
Clamp
the forceps at one shorter edge, so a long tissue is created for cleaning plan
surfaces.
Clean plane surfaces with liquid
Proceed with the following steps only if
the loosen dust was already removed and grease or fingerprints exist; see also
“Blowing
away dust from plane surfaces”.
a.
Wet
the entire surface of the created cleaning tissue (see above) with the cleaning liquid.
b. Wipe the surface carefully, without
pressure; only in one direction and only one time. The adhesion force of the liquid
will hold the tissue on the surface of the mirror, if the tissue is wet enough.
c.
Rotate
the forceps by 180 degrees and
repeat from step “a” with the other, clean surface of the cleaning tissue.
d.
Wait
10 to 20 seconds until the liquid is evaporated from the mirror surface; then
check the result with the magnifier.
e.
If
necessary, you can try to blow away dust or lint with the manual air blower.
f.
If
schlieren occurred (wiping the surface left marks on the surface; it happens
often if the dirt is a fingerprint or grease), repeat from step “a” with a new
prepared tool.
g.
If
the cleaning procedure was successful, protect the surface or mount the unit
immediately.
Create the tool for
cleaning “sunk-in” surfaces with liquid
Prepare the tweezers with a cleaning pad
as follows:
1. Cut a cleaning pad into two longer halves.
2.
Hold
the end of the cleaning pad half with the tweezers so, that the peak of the
tweezers reaches nearly until the middle of the cleaning pad.
3. Wrap the pad around the tweezers as shown.
Cleaning “sunk-in” surfaces with liquid
Proceed with the following steps only if
the loosen dust was already removed and grease or finger prints exist; see also
above “Blowing
away dust from sunk-in surfaces”.
a.
Wet the
peak of the
created tool (see above) with some drops of the cleaning liquid.
b.
Wipe
the surface carefully, without pressure only in one direction and only one time!
c.
Wait
10 - 20 seconds until the liquid is evaporated, then check the result with the
magnifier.
d.
If
necessary, you can try to blow away dust or lint with the manual air blower or
use the lens brush to remove lint
from the border.
e.
If
schlieren occurred (wiping the surface left marks; it happens often if the dirt
is a fingerprint or grease), repeat from step “a” with a new prepared tool.
f.
If
necessary, prepare the next tool with the other, unused half of the cleaning
pad, rotate the object to be cleaned by about 45 degrees and repeat from step
“a”. If the cleaning procedure was successful, protect the surface with the
clean dust cup or mount the unit immediately.
Clean the cover glass of
the camera’s CCD (often surface coated)
a.
By
using the air blower, loosen dust will be removed; blow the air from different
angles onto the surface (see above “Blowing away
dust from sunk-in surfaces”. Do not remove the cover glass from the CCD of
the camera for this purpose!
b.
Check
the surface with an appropriate magnifier and determine the location and the
kind of dirt.
c.
Clean
the surface as described above “Clean “sunk-in”
surfaces with liquid“.
d.
Look
at the surface by using an appropriate magnifier and check the surface for dust
or other contaminations and the position.
e.
If
necessary, lint can be removed from the cover glass border by using the manual air blower or the lens brush.
Clean the lens of the
camera adapter (surface coated)
a.
Dismount
the camera adapter and check both surfaces of the lens with an appropriate
magnifier and determine the location and the kind of dirt.
b.
Use
the air blower to remove loosen dust; see also “Blowing away
dust from sunk-in surfaces”.
c.
Clean
the surface as described above “Clean “sunk-in”
surfaces with liquid “.
d.
Look
at the surface by using an appropriate magnifier and check the surface for dust
or other contaminations and the position.
e.
If
necessary, lint can be removed from the lens border by using the manual air blower or the lens brush.
Clean the tube lens
(surface coated)
a.
By using the air blower, loosen dust will
be removed; blow the dust from different angles on both surfaces (see above “Blowing away
dust from sunk-in surfaces”.
b.
Check
both surfaces with an appropriate magnifier and determine the location and the
kind of dirt; dismount the tube lens if necessary.
c.
Use
the air blower to remove loosen dust; see also “Blowing away
dust from sunk-in surfaces”.
d.
Clean
the surface as described above “Clean “sunk-in”
surfaces with liquid “.
e.
Look
at the surface by using an appropriate magnifier and check the surface for dust
or other contaminations and the position.
f.
If
necessary, lint can be removed from the lens border by using the manual air blower or the lens brush.
Clean the objective
(surface coated)
a.
Remove the loosen dust as described under
“Blowing
away dust from sunk-in surfaces”.
b.
Clean
the metal protector part of the lens.
c.
Check
the position and the kind of contamination with the magnifier.
d.
If
necessary, prepare the cleaning tool as described above, the created Wooden or bamboo tool.
e.
Rotate
the prepared tool by approx. 270° on the lens, without pressure.
f.
Check
the result with the magnifier.
g.
Exchange
the cotton batting, rotate the objective by approx. 45º and repeat from
step “d” as necessary.
h.
If
necessary, lint can be removed from the lens border by using the manual air blower or
perhaps the lens brush.
Clean the brightfield
condenser
a.
Remove
the loosen dust as described under “Blowing away
dust from sunk-in surfaces”.
b.
Check
the position and the kind of contamination with the magnifier.
c.
If
necessary, prepare the cleaning tool as described above “Create the
tool for cleaning “sunk-in” surfaces
with liquid”.
d.
Execute
the procedure “Clean
“sunk-in” surfaces with liquid”
e.
If
necessary, lint can be removed from the lens border by using the manual air blower or
perhaps the lens brush.
Clean the brightfield
illumination mirror (surface coated)
a.
Remove
the loosen dust as described under “Blowing away
dust from plane surfaces”.
b.
Check
the position and the kind of contamination with the magnifier.
c.
If
necessary, prepare the cleaning tool as described above “Create the
tool for cleaning “sunk-in” surfaces
with liquid”. The tool should be smaller as shown above.
d.
Execute
the procedure “Clean “sunk-in” surfaces with liquid”;
use any opening to reach the contamination.
e.
If
necessary, lint can be removed from the mirror border by using the manual air blower or
perhaps the lens brush.
Clean the aspheric lens
or the diffuser
a.
Remove the loosen dust as described under
“Blowing
away dust from sunk-in surfaces”.
b.
Check
the position and the kind of contamination with the magnifier.
c.
If
necessary, put a cleaning pad onto the table and the aspheric lens on it.
d.
Spend
some drops of cleaning liquid onto the surface and wipe the surface carefully.
e.
Rotate
the lens or diffuser by 180º and repeat step “d”.
If necessary, lint can be removed from the
lens or diffuser by using the
manual air blower or the lens
brush after drying up.
Clean the illumination
source
Use a cleaning pad and cleaning liquid to
clean up the halogen lamp. Hold the lamp on the connector pins and clean the
entire glass surface of the lamp.
Check the cleanness of the lamp with the
magnifier.
Clean the preview mirror
(surface coated)
f.
Remove the loosen dust as described under
“Blowing away
dust from plane surfaces”.
g.
Check
the position and the kind of contamination with the magnifier.
h.
If
necessary, prepare the cleaning tool as described above “Create the tool for
cleaning plane surfaces with liquid”.
i.
Execute
the procedure “To clean plane surfaces with liquid”
j.
If
necessary, lint can be removed from the mirror border by using the manual air blower or the lens brush.
Clean the fluorescent illumination mirror
(surface coated)
a.
Dismount the fluorescent illumination
mirror if necessary.
b.
Remove
the loosen dust as described under “Blowing away
dust from plane surfaces”.
c.
Check
the position and the kind of contamination with the magnifier.
d.
If
necessary, prepare the cleaning tool as described above “Create the tool for
cleaning plane surfaces with liquid”.
e.
Execute
the procedure “To clean plane surfaces with liquid”
f.
If
necessary, lint can be removed from the mirror border by using the manual air blower or the lens brush.
Clean the fluorescent
condenser (surface coated)
a.
By using the air blower, loosen dust will be removed; blow
the dust from different angles on both surfaces (see above “Blowing away
dust from sunk-in surfaces”.
b.
Check both surfaces with an appropriate magnifier and
determine the location and the kind of dirt; dismount the lens if necessary.
c.
Use the air blower to remove loosen dust; see also “Blowing away dust from sunk-in surfaces”.
d. Clean the surface as
described above “To clean “sunk-in” surfaces with liquid “; if the lens is
dismounted, use the procedure as described above “To clean plane surfaces with
liquid”.
e.
Look at the surface by using an appropriate magnifier and
check the surface for dust or other contaminations and the position.
f.
If necessary, lint can be removed from the lens border by
using the manual air blower
or the lens brush.