KERN OBL 146 User manual

OBL-14-15-BA-e-2312
KERN & Sohn GmbH
Ziegelei 1
D-72336 Balingen
E-Mail: [email protected]
Tel: +49-[0]7433- 9933-0
Fax: +49-[0]7433-9933-149
Internet: www.kern-sohn.com
User instructions
Transmitted light phase contrast microscope
KERN OBL-14, OBL-15
OBL 146, OBL 155, OBL 156
Version 1.2
01/2023

OBL-14-15-BA-e-2312 2
GB
KERN OBL-14, OBL-15
Version 1.2 01/2023
User instructions
Phase contrast 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 ............................................................8
4Assembly....................................................................................10
4.1 Microscope head .................................................................................................................... 10
4.2 Objectives ............................................................................................................................... 10
4.3 Eyepieces................................................................................................................................ 10
4.4 Colour filter ............................................................................................................................. 10
4.5 PH condenser + PH slide....................................................................................................... 11
5Operation....................................................................................11
5.1 Getting started........................................................................................................................ 11
5.2 (Pre-) focussing ...................................................................................................................... 12
5.3 Adjusting the interpupillary distance................................................................................... 13
5.4 Dioptre adjustment................................................................................................................. 13
5.5 Adjusting the magnification.................................................................................................. 14
5.6 Adjusting the Koehler illumination....................................................................................... 15
5.7 Using eye cups ....................................................................................................................... 17
5.8 Using oil immersion objectives ............................................................................................ 18
5.9 Phase contrast unit ................................................................................................................ 19
6Changing the bulb .....................................................................21
7Changing the fuse......................................................................22
8Using optional accessories.......................................................22
8.1 Camera connection ................................................................................................................ 22
9Trouble shooting........................................................................23
10 Service........................................................................................25
11 Disposal......................................................................................25
12 Further information....................................................................25

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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 behandled 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.
If the original fuse should blow, it must only be replaced by an appropriate fuse.
Suitable replacement fuses are included with the delivery.
When carrying out any procedures whereby you come into contact with the electrical
system of the device, such as, for example, changing the bulb or fuse, only carry out
these procedures when the power is disconnected.

OBL-14-15-BA-e-2312 4
Under no circumstances should you touch the integrated halogen bulbs either during
operation or directly after use. These bulbs produce significant heat and therefore there
is a risk that the user could be severely burnt. So before handling the bulbs, you must
check that they have cooled down.
The microscope housing, on the other hand, is constructed so that no significant heat
radiation emanates from the device and that there is absolutely no risk of the user
burning themselves from the housing outer surfaces.
1.3 Storage
You should ensure that thedevice 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.

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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.

OBL-14-15-BA-e-2312 6
2 Nomenclature

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Rear view
Adjusting ring
torque
Carrying
handle
Main switch
Power
connection
Coarse
adjustment
knob
Fine
adjustment
knob
Fuse
Condenser
Focus dial
Adjusting ring
torque

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3 Technical data / Features
Model
KERN
Standard configuration
Optical system
Tube
Illumination
OBL 146
Infinity
Binocular
3W-LED (Transmitted light)
OBL 155
Infinity
Trinocular
12V / 20W Halogen (Transmitted light)
OBL 156
Infinity
Trinocular
3W-LED (Transmitted light)
Eyepieces
HWF 10x / Ø 20 mm
Objectives:
4x / PH10x / PH40x / 100x
Product dimensions:
395x200x380 mm
Packaging dimensions:
400x280x435 mm
Net weight:
6,7 kg
Gross weight:
8 kg
Input voltage:
AC 100-240V, 50-60Hz
Output voltage
OBL 155:
DC 1,2-12V
Output voltage
OBL 146 / OBL 156:
DC 5V
Fuse OBL 155:
2A 5x20mm

9 OBL-14-15-BA-e-2312

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4 Assembly
4.1 Microscope head
Inside the packaging the microscope head is already mounted but inclined towards the
rear. In order to turn it to the front you must loosen the fixing screw on the tube
connection point and after the turning fix it again with the screw. In case of removing
the head completely from the housing, you should always make sure that you do not
touch the lenses with your bare fingers and that no dust enters the apertures.
4.2 Objectives
The standard equipment of the series OBL-14 and OBL-15 includes two Infintiy E-Plan
objectives (4x / 100x) and two Infinity Plan objectives for phase contrast applications
(10x / 40x). 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.
4.3 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.
4.4 Colour filter
A blue colour filter is already an integral part of the microscopes of the series OBL-14
and OBL-15. It is fitted underneath the field diaphragm. In order to use suitable filters,
these can simply be placed in the ring bracket of the field lens.

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4.5 PH condenser + PH slide
The condenser is firmly fixed onto a holding ring (condenser holder) underneath the
microscope stage. There is the ability to adjust the height of the condenser, but not to
centre it.
We recommend that you use the coarse adjustment knob to bring the specimen stage
to its uppermost position when you need to remove the condenser. Then use the focus
dial of the condenser to move the condenser holder to a low position. In this way the
condenser can be taken off after loosening the screw on the left side holding ring. You
should avoid touching the optical lenses with bare fingers.
To attach a PH slide for phase contrast applications, it just has to be inserted into the
appropriate point on the front side of the condenser.
For further information on this please see 5.9 Phase contrast unit.
5 Operation
5.1 Getting started
The very first step is to establish a power connection using the mains plug or the
supplied power supply unit. 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 an object holder with the sample on the angle table. To do
this, the cover glass must be facing upwards. You can fix the object holder to the table
using the slide holder (see illustration on the left). To move the sample into the beam
path, you must use the adjustment wheels on the right of the angle table (see
illustration on the right).
You can position a total of two object holders at the same time.

OBL-14-15-BA-e-2312 12
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.

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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.

OBL-14-15-BA-e-2312 14
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.

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5.6 Adjusting the Koehler 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. If, as with the
devices in the KERN OBL-14 and OBL-15 series, the lighting can be set in accordance
with Koehler, the result is homogenous illumination of the slide and avoidance of
disruptive stray light.
The necessary control elements for this are:
•Height-adjustable and centre-adjustable condenser with aperture diaphragm
•Field diaphragm
Note: The condenser of the microscopes of the series OBL-14 and OBL-15 is not
centre-adjustable. Therefore it is not a full Koehler illumination. However this is
regarded as Fixed-Koehler, since the condenser is pre-centred.
When adjusting the Koehler lighting for the first time, you must first select the lowest
possible objective magnification, so that you can carry out the following steps.
1. Use the condenser focus wheel to position the condenser
directly below the specimen stage. Switch on the lighting and
use the coarse and fine adjustment knob to bring the slide
with the cover glass positioned facing upwards into focus.
2. Close the field diaphragm completely using its adjusting ring.
When you look in the microscope a blurred image appears in
the aperture.
3. Adjust the height of the condenser until the image from the
field diaphragm appears clearly in the field of view. For some
microscopes there is a risk that you will lift the condenser up
so high that it collides with the object holder. Therefore care
is needed when doing this.

OBL-14-15-BA-e-2312 16
4. Open the field diaphragm until it just disappears out of the
field of view.
If necessary, simply re-centre using the centring screws on
the condenser holder.
5. Use the aperture diaphragm of the condenser to find the
very best compromise between contrast and resolution for
the microscopic image. The scale divisions on the
condenser can be used as a guideline. Select 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 isthen 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.
6. It is possible to alter the brightness of the bulb using the dimmer. The brightness
is always controlled by the bulb brightness and not by the aperture diaphragm.
7. Possibly there is the need of re-adjusting the focus and x-y axis.
8. Observe the object.
If another magnification is selected afterwards, then the Koehler illumination does not
have to be reset from scratch, only the aperture diaphragm and field diaphragm need
to be adjusted as required.

17 OBL-14-15-BA-e-2312
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, youmust 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. witha damp
cloth).
Eye cups
High Eye Point eyepiece
(identified by the glasses symbol)

OBL-14-15-BA-e-2312 18
5.8 Using oil immersion objectives
The 100x objectives of the OBL-14 and OBL-15 series are objectives which can be
used with oil immersion (they are always marked with the word “OIL”). Using these
generates a particularly high resolution for microscopic images.
To use oil immersion correctly, please follow these steps.
1. Put a drop of oil on the cover glass (with standard thickness of 0.17 mm) of the
object slide.
2. Lower the specimen stage and position the 100x objective in the beam path.
3. Bring the specimen stage or object slide to the objective very slowly until there is
slight contact.
4. Observe the object.
The object slide and objective must not be pressed against each other. The oil
constitutes the contact layer.
If the contact is made too jerky, there is a chance that existing air bubbles in the oil
cannot escape. This would have a negative impact on image clarity.
After use or before changing the slide, any components which have been in contact
with the oil must be cleaned thoroughly. See also 1.4 Maintenance and cleaning.

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5.9 Phase contrast unit
Simple phase-contrast unit
This consists of a simple PH condenser, a PH objective with a specific magnification
(10x, 20x, 40x or 100x), a PH slider, which is adapted to the lens being used, a centring
telescope and a green filter.
The standard outfit of the models of the series OBL-14 and OBL-15 always includes a
10x and 40x phase contrast unit.

OBL-14-15-BA-e-2312 20
To use this, you need to position the desired PH objective in the beam path and
furthermore to place the corresponding PH slide into the insertion point of the PH
condenser.
With the surface marked with the magnification information facing up, the PH slider is
pushed into the insertion point on the PH condenser until stop. At this position the
phase ring of the PH slider is in the beam path and the phase-contrast application can
begin. In order to return to the bright field application, you must pull the PH slider out
of the condenser, so that the beam can pass the condenser without being affected by
the PH slider.
The PH objective has a PH ring in its lens system, just like the PH slider. Due to their
size on one hand and their positioning on the other, these two rings must be aligned
to one another in the beam path. The position of the ring in the objective cannot be
altered, that of the ring in the slider however can be. Before starting the phase-contrast
application you have to check if this alignment is given. For this you must install the
centring telescope to the tube connector instead of a standard eye piece and look
through it (The appearing image can be focussed by firstly loosening the locking screw
on the centring telescope, pull out the front part of the centring telescope to the correct
position and finally retightening the locking screw).
When installing the centring telescope instead of one of the eyepieces there is
appearing an image of a white (slide) and a black (objective) ring in the field of view
(see illustration). The black one is located centrally and the white one possibly shifted
to the side. In case of a shift, the position of the white ring has to be adjusted in order
to effect an exact overlapping of both rings by means of the two adjusting screws of
the condenser.
Depending on the preferences of the user, using a green filter can produce a more
effective and pleasant image. To achieve this, the green filter must be placed in the
ring bracket of the field lens.