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Leica DM750
Manual
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Manufacturer information
Published in November 2010 by:
Leica Microsystems (Schweiz) AG
Industry Division
Max Schmidheiny Strasse 201
CH-9435 Heerbrugg (Switzerland)
Responsible for contents:
Dietmar Gnass (Product Compliance)
Vincent Vaccarelli (Product Management)
In case of questions, please contact the hotline:
mqm-hotline@leica-microsystems.com
Leica DM750 Manual 2
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Chapter overview
Safety regulations 5
The Leica DM750 17
Ready! 20
Set! 30
Go! 43
Care of the Microscope 45
Troubleshooting 48
Dimensions 51
Leica DM750 Manual 3
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Contents
Safety regulations 5
Safety concept 6
Symbols used in this instruction manual 7
Important Notes 8
Intended Purpose of the Microscope 9
Instructions on use 10
Health risks and dangers of use 12
Information for the person responsible for the instrument 13
Care instructions 14
Accessories, maintenance and repair 15
Electrical data and ambient conditions 16
The Leica DM750 17
Introduction 18
Unpacking 19
Ready! 20
Substage Illumination 21
Attaching the viewing Tubes 22
Leica EZ Viewing Tube – integrated eyepieces 23
Leica Standard Viewing Tube – separated eyepieces 25
Eyecups 26
Installing Objectives 27
Installing the Substage Condenser 28
Set! 30
Turning on the microscope 31
Complete Condenser Centering 32
Using the Condenser 33
Prepare to View a Specimen Slide 34
Focusing 35
Viewing Tube Adjustment 36
Koehler Configuration 38
Oil Immersion Technique 40
Time Delay Shutoff 42
Go! 43
Ready! Set! Go! 44
Care of the Microscope 45
General maintenance 46
Troubleshooting 48
Troubleshooting 49
Dimensions 51
Leica DM750 Manual 4
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Safety regulations
Leica DM750 Manual 5
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Safety concept
The individual modules of the Leica DM
microscopy series include an interactive
CD-ROM with all relevant user manuals in
several languages. Keep it in a safe place, and
readily accessible to the user. User manuals and
updates are also available for you to download
and print from our web site at
www.leica-microsystems.com.
This user manual describes the special functions of the individual modules of the Leica
DM microscopy series and contains important
instructions for their operational safety, maintenance, and accessories.
The "Safety concept" booklet contains additional safety information regarding the service
work, requirements and the handling of
microscope, accessories and electrical accessories as well as general safety instructions.
You can combine individual system articles with
articles from external suppliers. Please read the
user manual and the safety requirements of the
supplier.
Before installing, operating or using the instruments, read the user manuals listed above. In
particular, please observe all safety instructions.
To maintain the unit in its original condition
and to ensure safe operation, the user must
follow the instructions and warnings contained
in these user manuals.
Leica DM750 Manual 6
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Symbols used in this instruction manual
Warning of a danger
This symbol indicates especially impor-
tant information that is mandatory to
read and observe.
Failure to comply can cause the following:
Ϙ Hazards to personnel
Ϙ Functional disturbances or damaged inst-
ruments
Warning of hazardous electrical voltage
This symbol indicates especially impor-
tant information that is mandatory to
read and observe.
Failure to comply can cause the following:
Ϙ Hazards to personnel
Ϙ Functional disturbances or damaged
instruments
Danger due to hot surface.
This symbol warns against touching
accessible hot surfaces, e.g. those of
light bulbs.
Important information
This symbol indicates additional infor-
mation or explanations that intend to
provide clarity.
Explanatory notes
ϐ This symbol within the text points to additi-
onal information and explanations.
Instructions for disposing of the instrument, accessory components, and
consumables.
Leica DM750 Manual 7
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Important Notes
Description
The Leica DM750 microscope meets today's
state of the art of technology. Nevertheless,
hazards may still arise during operation. The
potential risks are described below.
Before installing, operating or using the
instrument, it is mandatory to read this
user manual. In particular, please observe all
safety instructions.
Contact address
Leica Microsystems (Schweiz) AG
Industry Division
Max Schmidheiny Strasse 201
CH-9435 Heerbrugg (Switzerland)
User Manual
This user manual includes important instructions related to operating safety, maintenance
and accessories,
Your Leica DM750 microscope comes
with an interactive CD-ROM with all
relevant user manuals. Keep it in a safe place,
and readily accessible to the user. User manuals and updates are also available for you
to download and print from our website at
www.leica-microsystems.com.
Accessories from third-party suppliers
You can combine individual system articles with
articles from external suppliers. Please read the
user manual and the safety requirements of the
supplier.
Original condition
To maintain the unit in its original condition
and to ensure safe operation, the user must
follow the instructions and warnings contained
in these user manuals.
Legal requirements
Adhere to general and local regulations relating to accident prevention and environmental
protection.
EC Declaration of Conformity
Electrically operated accessories are constructed based on the state of the art of technology
and are provided with an EC Declaration of
Conformity.
Leica DM750 Manual 8
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Intended Purpose of the Microscope
The Leica DM750 microscope, for which
this instruction manual has been written, is intended for biological routine and
research applications. This includes examining specimens taken from the human body
for the purpose of gaining information about
physiological or pathological conditions
or inborn anomalies, or testing for safety
and compatibility for potential recipients,
or for monitoring therapeutic measures.
The above-named microscope complies with
the Council Directive 98/79/EEC concerning in
vitro diagnostics.
Caution! The Leica DM750 microscope
is not intended for use with biologically
hazardous materials.
Caution! The manufacturer assumes
no liability for any noncompliant use
or use outside of the specifications from Leica
Microsystems CMS GmbH as well as any risks
that may arise from such use. In such cases, the
Declaration of Conformity shall be invalid.
Caution! This (IVD) instrument is not
intended for use in a patient environment as defined by DIN VDE 0100-710.
It is also not intended to be combined with
medical devices as defined by EN 60601-1. If a
microscope is electrically connected to a medical instrument in accordance with EN 60601-1,
the requirements defined in EN 60601-1-1 shall
apply. Not suitable for examining potentially
infectious specimens.
Leica DM750 Manual 9
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Instructions on use
The Leica DM750 microscope may be
used only in closed rooms and must be placed
on a solid substrate.
The Leica DM750 microscope can be used in
clean rooms without any problems.
Always position the Leica DM750
microscope so that you can disconnect
it from the power supply at any time. The power
cable must remain accessible at all times,
because it is intended as a power disconnect
device.
Place of use
Only use the instruments in closed, dust free
rooms and between +10°C and +40°C. Protect
the devices from oil, chemicals and extreme
humidity. If using the devices outdoors, protect
them from dust and moisture. Never use electrical devices outdoors. Install electrical devices at
least 10 cm from the wall and away from flammable substances.
Avoid large temperature fluctuations, direct
sunlight and vibrations. These conditions
can distort measurements and micrographic
images.
In warm and warm-damp climatic zones,
the individual components require
special care in order to prevent the build-up of
fungus.
Non-intended use
Never install any other plug (NEMA
5-15P) or unscrew any mechanical
components unless expressly instructed to do
so in the instructions.
The devices and accessories described in
this instruction manual have been tested
for safety and potential hazards.
Leica DM750 Manual 10
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Instructions on use (continued)
The responsible Leica affiliate must be
consulted whenever the instrument is
altered, modified or used in conjunction with
non-Leica components that are outside of the
scope of this manual!
Unauthorized alterations to the instru-
ment or noncompliant use shall void all
rights to any warranty claims.
Transport
If at all possible, use the original packaging for
shipping or transporting individual modules.
In order to prevent damage from vibrations,
disassemble all moving parts that (according
to the user manual) can be assembled and
disassembled by the customer and pack them
separately.
Disposal
Once the product has reached the end of its
service life, please contact Leica Service or Sales
about disposal.
Please observe and ensure compliance with the
national laws and regulations that implement,
for example, the EC Directive WEEE.
Like all electronic devices, this inst-
rument, its accessory components
and consumables must never be disposed of
with general household waste. Disposal must
comply with locally applicable laws and regulations.
Integration in third-party products
When installing Leica products into third-party
products, the manufacturer of the complete
system or its dealer is responsible for following
all applicable safety instructions, laws and
guidelines.
Leica DM750 Manual 11
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Health risks and dangers of use
Health risks
Workplaces with microscopes facilitate
and improve the viewing task, but they
also impose high demands on the eyes and
holding muscles of the user. Depending on the
duration of uninterrupted work, asthenopia
and musculoskeletal problems may occur. For
this reason, appropriate measures for reduction
of the workload must be taken:
Ϙ Optimum workplace layout
Ϙ Frequent changes of activity
Ϙ Thorough training of the personnel, giving
consideration to ergonomic and organizational aspects
The ergonomic design and construction of the
Leica microscopy series are intended to reduce
the exertion of the user to a minimum.
Danger of infection
Direct contact with eyepieces is a
potential transmission method for
bacterial and viral infections of the eye.
The risk can be kept to a minimum by
using personal eyepieces for each indivi-
dual or detachable eyecups.
Dangers during use
Ϙ The Leica DM750 microscope may only be
connected to a grounded socket.
Ϙ The Leica DM750 microscope may not be
operated unless it is in proper functioning
condition.
LED Klasse 1 /LED 1 Laser Product
The illumination meets laser class 1 requirements in accordance with IEC 60825-1 "Safety
of Laser devices".
Caution: Hazardous radiation may occur if
controls, adjustment jigs, or procedures other
than those outlined in this User Manual are
used!
Class 1
LED Product
LED class 1
Leica DM750 Manual 12
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Information for the person responsible for the instrument
Information for the person responsible for
the instrument
Ϙ Ensure that the Leica DM750 microscope is
used only by qualified personnel.
Ϙ Ensure that this user manual is always
available at the Leica DM750 microscope.
Ϙ Carry out regular inspections to make
certain that the authorized users are
adhering to safety requirements.
Ϙ When instructing new users, do so
thoroughly and explain the meanings of
the warning signs and messages.
Ϙ Assign individual responsibilities for star-
ting, operating and servicing the instrument and monitor the observance of these
responsibilities.
Ϙ Do not use the Leica DM750 microscope
unless it is in perfect condition.
Ϙ Inform your Leica representative or Leica
Microsystems (Schweiz) AG, Industry
Division, 9435 Heerbrugg, Switzerland,
immediately of any product defect that
could potentially cause injury or harm.
Ϙ If you use accessories made by third-party
manufacturers with the Leica DM750
microscope, be sure that each such manufacturer confirms the safety-engineering,
harmless usability of the product and
observe the product's user manual.
Ϙ Modifications and maintenance of the Leica
DM750 microscope may only be performed
by professionals expressly authorized by
Leica.
Ϙ Only original Leica replacement parts may
be used in servicing the product.
Ϙ After service work or technical modifica-
tions, the unit must be reconfigured with
observance to our technical requirements.
Ϙ If the unit is modified or serviced by
unauthorized persons, is improperly
maintained (as long as maintenance was
not carried out by us), or is handled improperly, Leica will not accept any liability.
Ϙ The electric installation in the building
must conform to the national standard, e.g.
current-operated ground leakage protection (fault-current protection) is suggested.
Leica DM750 Manual 13
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Care instructions
General instructions
Ϙ Protect the Leica DM750 microscope
against damp, vapors, acids, alkalis, and
corrosive substances. Do not store chemicals in the vicinity.
Ϙ Protect the Leica DM750 microscope from
oil and grease. Never grease or oil mechanical parts or sliding surfaces.
Ϙ Follow the instructions of the disinfectant
manufacturer.
Ϙ It is advisable to enter a service agreement
with Leica Service.
Cleaning coated parts and plastic parts
Ϙ Dust and dirt particles should be removed
with a soft brush or lint-free cotton cloth.
Ϙ Remove coarse debris with a moistened
disposable cloth.
Ϙ Clinging dirt can be removed using petro-
leum ether or alcohol
Ϙ Acetone, xylene or nitro-containing thin-
ners must NOT be used.
Ϙ Never use chemicals to clean colored
surfaces or accessories with rubberized
parts. This could damage the surfaces, and
specimens could be contaminated by abraded particles.
Cleaning glass surfaces
Ϙ Remove dust using a dry and grease-free
brush made from hair, by blowing with
bellows, or by using a vacuum.
Ϙ Remove dirt using a clean cloth that has
been moistened with distilled water.
Ϙ Remove tough dirt using alcohol or petro-
leum ether.
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Accessories, maintenance and repair
Accessories
Only the following accessories may be used
with the Leica DM750 microscope:
Ϙ The Leica accessories described in this user
manual.
Ϙ Other accessories, provided that these have
been expressly approved by Leica as being
technically safe in this context.
Maintenance
Ϙ The Leica DM750 microscope is basically
maintenance-free. To ensure that it always
operates safely and reliably, we recommend
that you take the precaution of contacting
the responsible service organization.
You can arrange for periodic inspections
or, if appropriate, conclude a mainte-
nance contract with them.
Ϙ It is advisable to enter a service agreement
with Leica Service.
Ϙ For maintenance and repair, only OEM
spare parts may be used.
Repairs and service work
Ϙ Only original Leica Microsystems spare
parts may be used.
Ϙ Before opening the instruments, switch off
the power and unplug the power cable.
Ϙ Avoid contact with powered electrical
circuits, which can lead to injury.
Service address
In case of problems, please contact us as
follows:
Leica Microsystems (Schweiz) AG
Industry Division
Max Schmidheiny Strasse 201
CH-9435 Heerbrugg (Switzerland)
Phone +41 71 726 33 28
Leica DM750 Manual 15
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Electrical data and ambient conditions
Fuse Replacement
Unplug the instrument before changing any fuses. The Leica
DM750 has two fuses, which are located behind the power cord
receptacle.
Only use the following fuse types: 5×20 mm, 1 A/250V, fast-acting
fuse (# 13RFAG30003)
Electrical data
Input: 100-240 V, 50/60 Hz, 5 W (3 W LED)
General safety notes
This instrument of safety class 1 has been built and tested in accordance
with the following safety requirements for electrical equipment for measurement, control, and laboratory use:
EN 61010-1: 2002-08
EN 61010-2-101: 2008-06
IEC 61010-1: 2010-06
EN 61326-1: 2006-10
EN 61326-2-6: 2006-10
EN 55011: 2007+A2: 2010-05
EN 60825-1: 2008-05
IEC 60825-1: 2007-03
LED Class 1
In order to maintain this condition and to ensure safe operation,
the user must follow the instructions and warnings contained in
this instruction manual.
Environment
Temperature for use +10 °C … +40 °C
Storage temperature -20 °C … +52 °C
+50 °F to +104 °F
Manipulation shock 25 mm on 50 mm hard wood
Transport shock (unpacked) 100 g / 6 ms
Transport shock (packed) 800 mm free fall
Transport vibrations (unpacked) 5–200 Hz / 1.5 g
Air pressure during use and storage: 500–1060 mbar
Humidity during use and storage: 20–90%
Installation Category II (Overvoltage Category)
Pollution degree 2
Leica DM750 Manual 16
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The Leica DM750
Leica DM750 Manual 17
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Introduction
Thank you for purchasing the Leica DM750
Compound Microscope from Leica Microsystems. This model’s exclusive design features
and full range of accessories make it a truly
versatile, high quality-instrument for educational and routine clinical applications.
The instrument is to be used only as
described. Hazards to personnel may
result if used improperly.
Leica DM750 Manual 18
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Unpacking
Ϙ Carefully remove the microscope and any
components from the packing carton.
Ϙ Verify that all components are intact.
Ϙ Check the components against the planned
configuration.
Ϙ Optional items such as contrast accessories,
camera adapters, cameras, and carrying
cases are not shipped as part of the standard equipment. These items are delivered
in separate packages.
Ϙ Please do not discard any of the packing
materials. They should be used for safely
storing and transporting the instrument
should the need arise.
Leica DM750 Manual 19
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Ready!
Leica DM750 Manual 20
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Substage Illumination
Substage Illumination
The Leica DM750 is available with two
types of Substage Illumination. Identify
which type of Illumination you have, as this will
be important to know later.
Type 1: Standard illumination
Adjustable condenser centering with provided
tool.
Type 2: Koehler illumination
Adjustable condenser centering with
thumbscrews and adjustable Koehler field
diaphragm.
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Attaching the viewing Tubes
Tools used
Ϙ Allen key
There are two types of viewing tube.
Identify which viewing tube you have:
Type 1: Leica EZ Viewing Tube with integrated
eyepieces.
Type 2: Standard viewing tube with separate
eyepieces
1. Loosen the setscrew (on top of the stand)
using the Allen key provided.
2. Set the dovetail into the tripod mount and
tighten the setscrew carefully (without
using excessive force). This precisely positions the viewing tube onto the optical axis
of the microscope, regardless of the selected rotation.
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Leica EZ Viewing Tube – integrated eyepieces
Leica EZ viewing tube with integrated eyepieces.
To rotate the Leica EZ viewing tube,
either loosen the set screw on the stand
or replace the set screw with the (optional)
captive thumbscrew.
1. In order to use the captive wingscrew,
remove the setscrew that was delivered
with the stand.
Make sure that the wingscrew part
of the captive wingscrew has been
completely separated before you use the stand:
2. Reinstall the Leica EZ Viewing Tube onto
the stand.
3. Tighten the captive wingscrew using the
wrench included in the delivery package.
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Leica EZ Viewing Tube – integrated eyepieces (cont.)
You can now safely rotate the Leica EZ
viewing tube by loosening the captive
thumbscrew, rotating the viewing tube, and
tightening the captive thumbscrew again.
The eyepieces are integrated into the
Leica EZ Viewing Tube and preset; therefore, there is no need to adjust or install the
eyepieces.
Continue with the "Eyecups" section on page
26.
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Leica Standard Viewing Tube – separated eyepieces
Standard viewing tubes; tubes do not include
eyepieces yet
The standard viewing tube has a rota-
table dovetail. Therefore, you can now
rotate the standard viewing tube freely in any
orientation.
1. Insert the eyepieces into the tubes.
2. Secure the eyepieces in the tubes by tightening the silver screws at the bottom of the
tubes using a standard Phillips screwdriver
(not included in the delivery package).
The eyepieces will still rotate, but they
will be captive in the eyetubes.
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Eyecups
If you wear eyeglasses for microscope
viewing, keep the rubber eyecups folded
down. If you do not wear eyeglasses, you may
find it useful to unfold the rubber eyecups in
order to help block out ambient room light.
If you have purchased a standard
microscope configuration, you will
notice that the objectives are already installed
on the nosepiece and the substage condenser
is already installed on the stand. In this case,
go to section "Operation" on page 30. If you
purchased your Leica DM750 in the form of
individual components rather than the standard configuration, please continue with the
"Installing Objectives" section on page 27.
Leica DM750 Manual 26
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Installing Objectives
Installing Objectives
When rotating the objective nosepiece,
always use the knurled ring on the
objective nosepiece.
As you rotate the nosepiece clockwise, attach the
objectives by screwing them into the nosepiece
holes starting with the lowest magnification and
advancing to the highest magnification.
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Installing the Substage Condenser
Substage Condenser
The Leica DM750 has an open substage
condenser mount, therefore the conden-
ser needs to be installed.
The substage condenser mount is open
1. Move the specimen stage upwards as far as
it will go by using the coarse focusing knob
on the side of the microscope.
2. Move the condenser holder into the lowest
position by using the condenser focusing
knob on the left side of the stage mount.
3. Unscrew the two setscrews (or wingscrews for Koehler stands) on the condenser
holder.
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Installing the Substage Condenser (cont.)
4. Push the substage condenser under the
specimen stage into the holder by aligning the locating pin on the bottom of the
condenser with the slot on the rear side of
the fork.
5. Move the condenser into the highest position by using the condenser focusing knob
on the left side of the stage mount.
6. Tighten the two setscrews using the tool
included in the delivery package (or, for a
Koehler stand, tighten the two wingscrews)
so that the upper lens of the condenser is
centered under the objective in working
position and the substage condenser is
thus roughly centered.
You will center the condenser more accu-
rately when you get to the "Complete
Condenser Centering" section on page 32.
Leica DM750 Manual 29
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Set!
Leica DM750 Manual 30
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Turning on the microscope
Work Surface
Always use your microscope on a hard,
stable surface.
Power Cord
If the power cord is not already atta-
ched, attach it securely to the back of
the microscope.
Setting the Illumination Intensity
Set the illumination to the lowest
setting to start with, using the controller on the bottom left of the stand. The illumination control knob allows you to adjust the
intensity of light produced by the illumination
system.
Plug in and Turn on the Microscope
1. Plug the power cable of the microscope
into a corresponding grounded socket. A
grounded 3-wire cord is provided.
2. Switch on the microscope using the switch
at the bottom right of the microscope
stand.
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Complete Condenser Centering
If you have purchased a standard Leica
DM750 configuration, the condenser has
already been pre-centered by Leica Microsystems.
1. Open the condenser aperture by rotating
the knurled ring on the condenser to the
right.
Make sure that the condenser is in the
highest position.
2. Write an "X" on a piece of paper in the size
of a business card and place it onto the
light output of the microscope stand in
such a way that the "X" is centered over the
illumination.
3. Look at the X through the eyepieces and
center it in the field of view by tightening
the setscrews with the tool included in the
delivery package (or, for a Leica DM750
with Koehler illumination, tighten the
knurled screws).
Not centered
Centered
Leica DM750 Manual 32
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Using the Condenser
Using the Condenser
The condenser is furnished with an iris
diaphragm, which can be adjusted to
match the effective numerical aperture of the
objective
1. To open and close this diaphragm, simply
turn the knurled ring on the condenser to
the right or left so that the line on the ring
is aligned with the objective magnification
used.
Match the line of the rotating ring with the
objective magnification in use.
2. Open the iris diaphragm of the condenser
completely at first by turning the condenser ring all the way to the right.
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Prepare to View a Specimen Slide
1. Position a specimen slide on the specimen
stage by sliding it under the slide grips.
Slide grips hold the slide in place.
Slide grips
2. Using the X/Y-stage control, position the
specimen slide such that a part of the specimen is under the objective used.
Leica DM750 Manual 34
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Focusing
1. Rotate the objective nosepiece (using the
knurled ring) in such a way that the objective with the lowest magnification level is
rotated into the working position.
2. Move the specimen stage upwards by
turning the coarse focusing knob as far as
it will go to the maximum position.
Coarse focus adjustment knob
3. Look into the eyepieces and adjust the illumination intensity to a level that is comfortable for your eyes.
The stand of the Leica DM750 has been
calibrated at the factory so that the focus
can be found from this position within 1.5 rotations of the fine focus.
4. Bring the specimen into focus using the
fine focusing knob.
Leica DM750 Manual 35
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Viewing Tube Adjustment
Adjust the eyetubes
1. Adjust the tubes to your interpupillary
distance. Fold or unfold the eyetubes to
decrease or increase the distance between
the eyepieces until you see one illuminated
circle.
The viewing tubes maintain a constant
tube length for all interpupillary settings.
This means that a change of interpupillary
distance does not affect parfocality, magnification, or calibrations that depend on magnification.
Leica EZ Viewing Tube
Ϙ If you are using a Leica EZ viewing tube,
which has the eyepieces integrated with
the eyetubes, no additional adjustments
are necessary. Be sure you are wearing your
eyeglasses or contact lenses.
Ϙ If you have a Leica DM750 with stan-
dard illumination (without Koehler field
diaphragm), continue with the "Oil Immersion Technique" section on page 40.
Ϙ If you have a Leica DM750 with Koehler
field diaphragm, continue with the "Koehler Configuration" section on page 38.
Standard Viewing Tube with Two Fixed
Eyepieces
Ϙ If you are using a standard viewing tube
with two fixed eyepieces (no focusing
eyepieces), no additional adjustments
necessary. Be sure you are wearing your
eyeglasses or contact lenses.
Ϙ If you have a Leica DM750 with stan-
dard illumination (without Koehler field
diaphragm), continue with the "Oil Immersion Technique" section on page 40.
Ϙ If you have a Leica DM750 with Koehler
field diaphragm, continue with the "Koehler Configuration" section on page 38.
Standard Viewing Tube with One or Two
Focusing Eyepieces
If you are using a standard viewing tube with
one or two focusing eyepieces, you need to
make some adjustments.
1. Set the focusing eyepieces to "0".
Leica DM750 Manual 36
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Viewing Tube Adjustment (cont.)
If you are comfortable wearing your
corrective lenses (contact lenses or
eyeglasses) for microscope viewing, leave them
on and your adjustments will be minimal.
2. Using the fine focus adjusting knob, focus
on the specimen while looking through
only one of the eyepieces (when using one
eyepiece that is focusable and one that is
not focusable, look through the one that is
not focusable). To help focus, cover or close
the other eye.
3. Now look with the other eye just through
the other eyepiece (focusing eyepiece). This
time, focus the specimen by using the focusing capability in the focusing eyepiece.
When doing so, do not change the
height of the specimen stage.
4. Grip the knurled ring on the focusing
eyepiece with one hand and rotate the top
of the eyepiece with the other hand until
the specimen is in focus for this eye and
this focusing eyepiece. This corrects for any
vision differences between your right eye
and left eye.
5. Now, switch to an objective with a high
magnification level (no oil objective) and
bring the microscope into focus while
looking through the eyepieces with both
eyes.
The higher magnifications have a shallo-
wer depth of field. Therefore, after focusing with a high magnification, you will find that
when you change to lower magnifications, you
only have to adjust the fine focus slightly, if at
all.
Ϙ If you use a DM750 with standard illumi-
nation, continue with the "Oil Immersion
Technique" section on page 40.
Ϙ If your DM750 has a Koehler configuration,
please continue with the next section,
"Koehler Configuration", on page 38.
Leica DM750 Manual 37
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Koehler Configuration
If your Leica DM750 is fitted with a field diaphragm for Koehler Illu-
mination, use the following procedure to assure condenser cente-
ring and focus.
1. Connect the Koehler field diaphragm to the base of the microscope
so that the diaphragm leaves are in the field of view when you look
through the eyepieces.
Close the Koehler field diaphragm
Close the Koehler field diaphragm
2. Focus the leaves of the field diaphragm using the condenser focusing
knob on the left side of the stage mount.
Condenser focusing knob
Leaves are in sharp focus
Leica DM750 Manual 38
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Koehler Configuration (cont.)
3. Turn the condenser centering wingscrews simultaneously to center
the image of the field diaphragm.
4. Open the field diaphragm until the diaphragm leaves are just outside
of the field of view.
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Oil Immersion Technique
1. Search for the area on the specimen slide
that you want to study.
2. Move the specimen stage down to the
lowest position using the coarse adjustment knob.
3. Add a drop of immersion oil from Leica
to the area of the specimen slide you are
studying.
4. Rotate the oil immersion objective (the
objective labeled "OIL") to the working
position.
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Oil Immersion Technique (cont.)
5. Slowly move the specimen stage upwards
using the coarse adjustment knob until
the oil drop on the slide comes into direct
contact with the lens of the oil immersion
objective.
6. Hold the knurled ring on the objective
turret and swing the objective back and
forth to eliminate air bubbles. Then bring
the oil objective into the final position, so
that the oil drop is between the front lens
of the objective and the specimen slide.
7. Look through the microscope and slowly
rotate the fine adjustment knob, so that the
specimen stage moves upwards until the
specimen is in focus.
8. If you are finished working with the oil
immersion objective, clean the front side
of the objective, the specimen slide, and all
other surfaces that have come into contact
with the oil, following the instructions in
the "Care of the Microscope" section on
page 46.
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Time Delay Shutoff
The Leica DM750 is equipped with a time
delay shutoff capability, which automatically turns the illumination off after 2 hours of
no changes in the intensity control.
Ϙ All four-position nosepiece stands have
the time delay shutoff enabled as a default
(mostly educational applications).
Ϙ All five-position nosepiece stands have the
time delay shutoff disabled as a default
(mostly clinical applications).
Changing the status of the time delay
shutoff
1. Rotate the intensity regulator to the lowest
level.
2. Switch on the instrument.
3. Rotate the intensity regulator to the highest level and then back to the lowest level
within five seconds.
Ϙ The LED Illumination will flash to indicate
the time delay shutoff status was changed.
Ϙ The LED Illumination will flash two times
slowly then stay on when you disable the
Time Delay Shutoff.
Ϙ The LED Illumination will flash three times
quickly then stay on when you enable the
Time Delay Shutoff.
When you turn the power off and then
turn the power on again, the system will
be in the last Time Delay Shutoff status (Enabled
or Disabled) and you will not see any blinking.
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Page 43
Go!
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Ready! Set! Go!
Now all you need to do is change objectives, set
the condenser aperture (and field diaphragm if
you have a DM750 Koehler Stand) appropriately
for the objective magnification you are using,
and enjoy the view!
Leica DM750 Manual 44
Page 45
Care of the Microscope
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Page 46
General maintenance
Storage and handling
Always use both hands to carry the
microscope. There is a handle on the
back of the microscope and an undercut in the
front for this purpose.
Ϙ The cord wrap allows you to wrap the cord
in such a way that only the length you need
is extended.
Ϙ Keep all optical components clean. Clean-
liness is important for maintaining good
optical performance.
Ϙ The microscope should always be covered
with the plastic dust cover (provided with
the instrument) when it is not in use.
Instructions for cleaning
Ϙ If any optical surface becomes coated with
dust or dirt, clean the surface by blowing it
off with a syringe or brushing it off with a
camel hair brush before attempting to wipe
the surface clean.
Ϙ Optical surfaces should be cleaned using
a lint-free cloth, lens cloth or cotton swab
moistened with a commercially available
glass cleaner.
Ϙ It is very important to avoid the excessive
use of solvents, so use them sparingly. The
lint-free cloth, lens tissue or cotton swab
should be moistened with solvent, but
not be wet enough for the solvent to seep
around the lens.
Leica DM750 Manual 46
Page 47
General maintenance (cont.)
Ϙ No part of the microscope is quite so vulne-
rable to collecting dirt, dust, and oil as the
front lens of the objective. Whenever you
encounter lack of contrast, cloudiness or
poor definition, carefully check the condition of the front lens with a magnifier.
Ϙ The lower magnification objectives have
fairly large front lenses and can be cleaned
with a cloth or lens tissue wrapped around
a finger and moistened with methanol.
Ϙ Cleaning 40× and 100× objectives requires
more care. Note: To attain the typical flatness for objectives with higher magnification, the objective has a small concave front
lens with a very small radius and slight
curvature. The surface of this front lens can
be readily cleaned with a toothpick covered with a cotton tip, or with a small cotton
swab. Soak the cotton with isopropanol
and squeeze it out until it is almost dry
again. Wipe the front lens lightly without
applying undue force or scrubbing action.
Make sure that the cotton tip contacts the
concave lens surface. Check the objective
with a magnifier after cleaning.
Ϙ If you need to remove the microscope’s
viewing body, be careful not to accidentally
touch the outer lens surface (located on
the underside of the body). Fingerprints on
this surface will reduce image clarity. This
lens can be cleaned in the same manner as
objectives and eyepieces.
Mechanical Maintenance
Ϙ Use the dust cover. It is the most impor-
tant way to keep the microscope in good
mechanical and physical condition.
Ϙ The Leica DM750 has a durable finish. All
non-optical parts of the instrument can
be cleaned with isopropanol or soap and
water. Avoid the use of all other organic
solvents when cleaning the instrument.
Illumination
Ϙ The Leica DM750 uses LED illumination.
Therefore, no lamp changing is required for
the life of the microscope.
Leica DM750 Manual 47
Page 48
Troubleshooting
Leica DM750 Manual 48
Page 49
Troubleshooting
Stand
Make sure that the socket has voltage.
The microscope does not respond.
Focus
The specimen cannot be brought into focus.
Dark field
No definite DF contrast is possible.
The image is not uniformly illuminated. The objective magnification is too weak. Use a higher magnification.
Unwanted stray light. Clean the specimen and neighboring lens surfaces.
Polarization
Check the cable connections.
Make sure that the stand is connected to the power supply.
Check whether the fuse is defective and replace it if necessary (see page 16).
Use the correct immersion medium.
Lay the specimen with the cover glass toward the top.
Make sure that the cover slip thickness is correct and that it meets the specifications on the objective.
Make sure that a DF objective is being used.
The objective aperture is too high (maximum 0.75/ 1.10); if necessary, reduce
the objective aperture through the iris diaphragm on the objective.
Check the condenser centering.
Open the aperture diaphragm completely.
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Page 50
Troubleshooting (continued)
Polarization contrast cannot be adjusted.
Phase contrast
Phase contrast cannot be adjusted.
Specimen Stage
Positioning range of the stage in the x-direction decreases after working a long time.
Bring the polarizer and analyzer into cross position until they reach maximum
darkness (without specimen).
The specimen is too thick, too thin, or too brightly stained.
Refractive indexes of the mounting medium and specimen are identical, so that
there is no phase jump.
The cover glass is not placed uniformly.
Check that the correct light ring is positioned.
Check the centering of the light rings.
Check the condenser centering.
Open the aperture diaphragm completely.
Move the mechanical stage with coaxial drive all the way to the left.
Manually press the screw that holds the mechanical stage even farther to the
left, as far as it will go. Then move the mechanical stage with coaxial drive all the
way to the right.
Manually press the screw that holds the mechanical stage even farther to the
right, as far as it will go.
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Page 51
Dimensions
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Leica DM750 Manual 52
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