KERN Optics OKM-1 User manual

OKM-1-BA-e-2311
KERN & Sohn GmbH
Ziegelei 1
D-72336 Balingen
E-Mail: [e-mail]
Tel: +49-[0]7433- 9933-0
Fax: +49-[0]7433-9933-149
Internet: www.kern-sohn.com
User instructions
Metallurgical microscope
KERN OKM-1
OKM 173
Version 1.1
06/2023

OKM-1-BA-e-2311 2
GB
KERN OKM-1
Version 1.0 01/2015
User instructions
Metallurgical microscope
Table of contents
1Before use ...................................................................................................... 3
1.1 General notes............................................................................................................................ 3
1.2 Notes on the electrical system................................................................................................ 3
1.3 Storage ...................................................................................................................................... 4
1.4 Maintenance and cleaning....................................................................................................... 5
2Nomenclature................................................................................................. 6
3Technical data / Features .............................................................................. 9
4Assembly...................................................................................................... 11
4.1 Reflected light unit ................................................................................................................. 11
4.2 Microscope head .................................................................................................................... 11
4.3 Objectives ............................................................................................................................... 11
4.4 Eyepieces ................................................................................................................................ 11
5Operation...................................................................................................... 12
5.1 Getting started ........................................................................................................................ 12
5.2 (Pre-) focussing ...................................................................................................................... 13
5.3 Adjusting the interpupillary distance ................................................................................... 14
5.4 Dioptre adjustment................................................................................................................. 14
5.5 Adjusting the magnification .................................................................................................. 15
5.6 Adjusting the illumination ..................................................................................................... 16
5.7 Using eye cups ....................................................................................................................... 17
6Changing the bulb ....................................................................................... 18
7Using optional accessories ........................................................................ 18
7.1 Camera connection ................................................................................................................ 18
8Trouble shooting.......................................................................................... 19
9Service .......................................................................................................... 21
10 Disposal........................................................................................................ 21
11 Further information...................................................................................... 21

3 OKM-1-BA-e-2311
1 Before use
1.1 General notes
You must open the packaging carefully, to make sure that none of the accessories in
the packaging fall on the floor and get broken.
In general, microscopes should always be handled carefully because they are
sensitive precision instruments. When using or transporting the microscope it is
particularly important to avoid abrupt movements, as this may damage the optical
components.
You should also avoid getting dirt or finger prints on the lens surface, because in
most cases this will reduce image clarity.
To maintain the performance of the microscope, it must never be disassembled. So
components such as lenses and other optical elements should be left as they were
before use. Also the electrical parts on the rear and base of the device must not be
tampered with, as in this area there is an additional risk of triggering an electric
shock.
1.2 Notes on the electrical system
Before connecting to a mains power supply, you must make sure that you are using
the correct input voltage. The information to select the correct mains cable is located
on the device, on the rear of the product directly above the connection socket. You
must comply with this information. If you do not comply with these specifications, then
fires or other damage to the device could occur.
The main switch must also be switched off before the mains cable is connected. In
this way you will avoid triggering an electric shock.
If you are using an extension cable, then the mains cable you use must be earthed.

OKM-1-BA-e-2311 4
1.3 Storage
You should ensure that the device is not exposed to direct sunlight, temperatures
which are too high or too low, vibrations, dust or a high level of humidity.
The ideal temperature range is between 0 and 40°C and a relative humidity of 85%
should not be exceeded.
The device should always be located on a rigid, smooth, horizontal surface.
When the microscope is not being used, you should cover it with the enclosed dust
protective cover. When doing this, the power supply is stopped by switching off at the
main switch and unplugging the mains cable. If the eyepieces are being stored
separately, the protective caps must be fitted to the tube connectors. In most cases,
if dust and dirt gets inside the optical unit of a microscope this can cause irreversible
errors or damage.
The best way to store accessories which consist of optical elements, such as, for
example, eyepieces and objectives, is in a dry box with desiccant.

5 OKM-1-BA-e-2311
1.4 Maintenance and cleaning
In any event, the device must be kept clean and dusted regularly.
If any moisture should be occur, before you wipe down the device you must ensure
that the mains power is switched off.
When glass components become dirty, the best way to clean them is to wipe them
gently with a lint-free cloth.
To wipe oil stains or finger prints off the lens surface, moisten the lint free cloth with a
mixture of ether and alcohol (70 / 30 ratio) and use this to clean the lens.
You must be careful when handling ether and alcohol, as these are highly flammable
substances. You must therefore keep it away from naked flames and electrical
devices which can be switched on and off, and only use it in well-ventilated rooms.
However organic solutions of this type should not be used to clean other components
of the device. This could lead to damage to the paint finish. To do this, it is sufficient
to use a neutral cleaning product.
You could also use the following cleaning products to clean the optical components:
•Special cleaner for optical lenses
•Special optical cleaning cloths
•Bellows
•Brush
When handled correctly and checked regularly, the microscope should give many
years of efficient service.
Should repairs still be necessary, please contact your KERN dealer or our Technical
Department.

OKM-1-BA-e-2311 6
2 Nomenclature

7 OKM-1-BA-e-2311
Rear view

OKM-1-BA-e-2311 8
Reflected light unit

9 OKM-1-BA-e-2311
3 Technical data / Features
Model
KERN
Standard configuration
Optical system Tube Illumination
OKM 173 Infinity Trinocular 5W LED (Incident)
Eyepieces:
WF 10x / Ø 18 mm
Objectives:
5x / 10x / 20x (LWD) / 40x (LWD)
Product dimensions:
440x200x460 mm
Packaging dimensions:
555x315x400 mm
Net weight:
9,5 kg
Gross weight:
8 kg
Input voltage:
AC 100-240V, 50-60Hz
Output voltage:
DC 5V, 1A

OKM-1-BA-e-2311 10

11 OKM-1-BA-e-2311
4 Assembly
4.1 Reflected light unit
First you must loosen the fixing screw on the tube connection point and remove the
black protective cover.
You can then insert the round dovetail bracket on the light unit into the round dovetail
bracket on the housing and fix it with the fixing screw. When doing this, you should
always make sure that you do not touch the lenses with your bare fingers and that no
dust enters the apertures. The lamp housing should be straightly directed towards
the rear (parallel with the microscope housing).
Now you have to attach the plug of the connecting cable to the connection socket
(OUT) on the rear of the microscope. For the power supply, the connecting cable is
plugged into the connection socket (IN).
Finally the analyser and polariser slides can be fitted to the appropriate slots (see
page 8).
4.2 Microscope head
First you must loosen the fixing screw on the connection point of the reflected light
unit and remove the black protective cover.
You can then insert the round dovetail bracket on the head into the round dovetail
bracket on the light unit and fix it with the fixing screw. When doing this, you should
always make sure that you do not touch the lenses with your bare fingers and that no
dust enters the apertures.
4.3 Objectives
All four objectives are already mounted to the nosepiece. After removing the
protective foil they are ready for use. They are ranged in such a way that if you turn
the nosepiece clockwise, the objective with the next higher magnification appears.
When the objectives need to be dismounted, you should always make sure that you
do not touch the lenses with your bare fingers and that no dust enters the apertures.
For objectives which are marked “OIL”, you must use an immersion oil with the
lowest level of inherent fluorescence.
4.4 Eyepieces
You must always use eyepieces with the same magnification for both eyes. These
are simply placed onto the tube connectors, once you have first removed the plastic
protective caps. There is no way of fixing them. You should always make sure that
you do not touch the lenses with your bare fingers and that no dust enters the
apertures.

OKM-1-BA-e-2311 12
5 Operation
5.1 Getting started
The very first step is to establish a power connection using the mains plug. You
should first adjust the dimmer to a low level, so that when you look through the
eyepiece for the first time, your eyes are not immediately subject to a high level of
light. You can now switch on the lighting using the main switch.
The next step is to place a sample on the angle table. To move the sample into the
beam path, you must use the adjustment wheels on the right of the angle table (see
illustration).

13 OKM-1-BA-e-2311
5.2 (Pre-) focussing
When you are observing an object, you must have the correct distance to the
objective to achieve a sharp image.
In order to find this distance at the beginning (without other default settings of the
microscope) place the objective with the lowest magnification in the beam path, look
through the right eyepiece with the right eye and turn it slowly using the coarse
adjustment knob (see illustration).
The simplest way of doing this would be to first raise the specimen stage (using the
coarse adjustment knob) until it is just under the objective and then lower it slowly. As
soon as an image is recognisable (no matter how sharp), then you should only adjust
the focus using the fine adjustment knob.
Adjusting the torque of the coarse and fine adjustment knob
Next to the left adjustment wheel for the coarse and fine adjustment knob there is a
ring which you can use to alter the torque of these wheels. Turning it in a clockwise
direction reduces the torque and turning it in an anti-clockwise direction increases it.
On one hand, this function can help to make it easier to adjust the focus and on the
other hand it can prevent the specimen stage from slipping down unintentionally.
Important:
In order to avoid damaging to the focussing system, the left and right adjustment
wheels for the coarse and fine adjustment knob must never be rotated at the same
time in opposite directions.

OKM-1-BA-e-2311 14
5.3 Adjusting the interpupillary distance
With binocular viewing, the interpupillary distance
must be adjusted accurately for each user, in
order to achieve a clear image of the object.
While you are looking through the eyepieces, use
your hands to hold the righthand and lefthand tube
housing firmly. By pulling them apart or pushing
them together, you can either increase or reduce
the interpupillary distance (see illustration). As
soon as the field of views of the lefthand and
righthand eyepieces completely overlap each
other, i.e. they combine to form a circular image, then the interpupillary distance is
set correctly.
5.4 Dioptre adjustment
The eye strengths of each eye of the microscope user can often be slightly different,
which in daily life has no consequences. But when using a microscope this can
cause problems in achieving precise focussing.
You can use a mechanism on the left tube connector (dioptre adjustment ring) to
compensate for this as follows.
1. Look through the right eyepiece with the right eye and bring the object into focus
by using the coarse and fine adjustment knob.
2. Then look through the left eyepiece with the left eye and use the dioptre
adjustment ring to focus the image.
To do this, you just need to turn the ring in both directions (see illustration), to find
out where the image is at its most focussed.

15 OKM-1-BA-e-2311
5.5 Adjusting the magnification
After prefocussing has been carried out using the objective with the lowest
magnification (see section 5.2), you can then adjust the overall magnification using
the nosepiece, as necessary. By turning the nosepiece you can bring any one of the
four other objectives into the beam path.
When adjusting the nosepiece, you must take the following points into account:
- The required objective must be properly locked in
place at all times.
- The nosepiece should not be rotated by holding
individual objectives, you should use the silver
ring above the objectives (see illustration).
- When rotating the nosepiece you must always make sure that the objective which
is about to be positioned in the beam path does not touch the object holder. This
can lead to significant damage to the objective lens.
We recommend that you always check from the side to make sure that there is
sufficient leeway. If this should not be the case, the specimen stage must be
lowered accordingly.
If you have focussed the object to be observed for a specific magnification, then if
you select the objective with the next greatest magnification, then the object will be
slightly out of focus. Use the fine adjustment knob to make a slight adjustment and
restore the focus.

OKM-1-BA-e-2311 16
5.6 Adjusting the illumination
To make sure that perfect image results are achieved during microscopic
observation, it is important that the direction of light of the microscope is optimised.
The necessary control elements for this are:
•Aperture diaphragm
•Filter wheel
•Analyser/Polariser
1. Use the aperture diaphragm of the condenser to find the
very best compromise between contrast and resolution for
the microscopic image. Select the right setting in
accordance with the objective being used.
The view in the tube without the eyepiece should look
something like the illustration on the right.
The diameter of the aperture diaphragm which is then
visible should make up approximately 2/3 of the pupil
diameter.
If the eyepiece should be removed, for checking, then
please make sure that no dirt or dust falls into the tube.
The brightness is always controlled by the bulb brightness (dimmer) and not by
the aperture diaphragm.
2. With the filter wheel (blue, green, yellow, grey, empty) the light colour can be
changed in accordance to the application.
3. Especially for metallurgical applications use is made of the polarising method to
carry out observations in this field. The main components for this are polariser
and analyser (see page 8). As soon as the polariser and the analyser are inserted
to the beam path, by putting the slides into the slots, the microscope is prepared
for the polarising method.
According to each type of application there must be selected the appropriate
position of the wheel on the analyser slide.

17 OKM-1-BA-e-2311
5.7 Using eye cups
The eye cups supplied with the microscope can basically be used at all times, as
they screen out intrusive light, which is reflected from light sources from the
environment onto the eyepiece, and the result is better image quality.
But primarily, if eyepieces with a high eye point (particularly suitable for those who
wear glasses) are used, then it may also be useful for users who don’t wear glasses,
to fit the eye cups to the eyepieces.
These special eyepieces are also called High Eye Point eyepieces. They can be
identified by the glasses symbol on the side. They are also marked in the item
description by an additional “H” (example: HSWF 10x Ø 23 mm).
When fitting the eye cups, make sure that the dioptre setting is not moved. We would
therefore advise that you hold the dioptre compensation ring on an eyepiece with one
hand while you fit the eye cup with the other.
Before using the microscope, users who wear glasses must remove the eye cups,
which you may find on High Eye Point eyepieces.
As the eye cups are made of rubber, you must be aware that when you are using
them, they can become slightly dirty through grease residues. In order to maintain
hygiene, we would therefore recommend that you clean the eye cups regularly (e.g.
with a damp cloth).
Eye cups
High Eye Point eyepiece
(identified by the glasses symbol)

OKM-1-BA-e-2311 18
6 Changing the bulb
If a defect occurs in the lighting unit or other electrical components, the Technical
Service department of Kern & Sohn GmbH must be contacted for repair.
7 Using optional accessories
7.1 Camera connection
OKM 173
Due to the trinocular tube, which is a standard fitting for the OKM 173, it is possible to
connect microscope cameras to the device, in order to digitally record images or
sequences of images of an object being observed.
After the plastic cover has been removed from the camera adapter connector on the
top of the microscope head, then a suitable adapter must be fitted.
In general there are two C-mount adapters available for this (1x and 0.5x
magnification, see Chapter 3 Features). After fitting one of these adapters it can be
fixed with the fixing screw. A camera which has a C-mount thread is then screwed on
top of the adapter.
We recommend that you first adjust the field of view using the eyepieces on the
device for the existing requirements, and then carry out the observation using the
microscope camera (i.e. using the PC screen which is connected).
The tube has a light distribution that guarantees the providing of light for the
eyepieces and the camera connection at the same time. This means that it is
possible to simultaneously observe by the eyepieces and PC screen.
For C-mount adapters, which have their own integrated magnification, the image
which is shown on the camera connected to the device can often have a different
level of focus compared with the image on the eyepiece.
In order to be able to bring both images into focus, the focus can be adjusted by
those adapters.

19 OKM-1-BA-e-2311
8 Trouble shooting
Problem Possible causes
The bulb does not light
The mains plug is not correctly plugged in
There is no power at the socket
Defective bulb
The bulb blows immediately The specified bulb or fuse has not been used
The field of view is dark
The aperture diaphragm and/or field
diaphragm are not opened wide enough
The selector switch for the beam path is set
to “Camera”
The condenser is not correctly centred
You cannot adjust the brightness
The brightness control has been set
incorrectly
The condenser has not been correctly
centred
The condenser is too low
The field of view is dark or is not
correctly
illuminated
The objective is not positioned correctly on
the beam path
The selector switch for the beam path is
between two settings
The nosepiece is not correctly fitted
The condenser is not correctly fitted
An objective is being used which doesn’t
match the lighting area of the condenser
The condenser has not been correctly
centred
The field diaphragm is closed too tightly
The bulb is not correctly fitted
The field of view of one eye does not
match that of the other eye
The interpupillary distance is not correctly
adjusted
Dioptre setting has not been carried out
correctly
Different eyepieces are used for the
righthand and lefthand side
The eyes are not used to using a microscope

OKM-1-BA-e-2311 20
Problem Possible causes
Blurred details
Bad image
Bad contrast
Vignetted field of view
The aperture diaphragm is not opened wide
enough
The condenser is too low
The objective does not belong to this
microscope
The front lens of the objective is dirty
An immersion object has been used without
immersion oil
The immersion oil contains air bubbles
The condenser is not correctly centred
The recommended immersion oil has not
been used
Dirt / dust on the objective
Dirt /dust on the front lens of the condenser
Dirt or dust in the field of view
Dirt / dust on the eyepieces
Dirt / dust on the front lens of the condenser
Dirt / dust on the object
One side of the image is blurred
The stage was not correctly fitted
The objective is not positioned correctly on
the beam path
The nosepiece is not correctly fitted
The upper side of the object is facing down
The image flickers
The nosepiece is not correctly fitted
The objective is not positioned correctly on
the beam path
The condenser has not been correctly
centred
The coarse adjustment knob is difficult to
turn
The rotational resistance brake is too
tight
The angle table is blocked by a
solid body
The stage moves down on its own
The fine adjustment knob moves on its
own
The rotational resistance brake is not tight
enough
When you move the table, the image
becomes blurred The stage was not correctly fitted