OPTO-EDU A15 0908 Series User manual

Version:V1.0
A15.0908 Series
Polarizing Microscope
INSTRUCTIONS
This instruction manual is for the operation guide, troubleshooting and
maintenance to the A15.0908 Series Polarizing Microscope. Please study this
manual thoroughly before operating, and keep it with the instrument. The
manufacturer reserves the rights to the modifications by technology
development. On the basis of operation ensured, technical specifications
may be subject to changes without notice.

Contents A15.0908 Series
Before Use
1. Components............................................................................................................................... 1
2. Assembling ................................................................................................................................3
2-1 Assembling Scheme......................................................................................................... 3
2-2 Assembling Steps............................................................................................................. 4
3. Operation .................................................................................................................................. 8
3-1 Set Illuminations ............................................................................................................. 8
3-2 Adjust Focusing .............................................................................................................. 9
3-3
Adjust the Focusing Tension........................................................................................... 9
3-4
Adjust the Diopter........................................................................................................... 9
3-5 Adjust the Interpupillary Distance................................................................................ 10
3-6 Use the Eye-cap ............................................................................................................ 10
3-7 Adjust the Objective Center .......................................................................................... 10
3-8 Center the Condenser ....................................................................................................11
3-9 Adjust the Field Diaphragm.......................................................................................... 12
3-10 Adjust the Aperture Diaphragm.................................................................................. 12
3-11 Adjust the Analyzer..................................................................................................... 13
3-12 Adjust the Polarizer .................................................................................................... 13
3-13 Check H-V Location.................................................................................................... 14
3-14 Use the Compensator.................................................................................................. 14
3-15 Use the Rotatable Stage.............................................................................................. 14
3-16 Use the Color Filter.................................................................................................... 14
3-17 Replace the Fuse......................................................................................................... 15
3-18 Use the Bertrand Lens ................................................................................................ 15
3-19 Use the Trinocular Head, TV and Photography Device.............................................. 16
3-20 Use the Digital Viewing Head..................................................................................... 17
4. Troubleshooting....................................................................................................................... 19

Before Use A15.0908 Series
1. Operation Notice
1. As the microscope is a high precision
instrument, always operate it with care, and
avoid physical shake during the operation.
2. Do not expose the microscope in the sun
directly, either not in the high temperature, damp,
dust or acute shake. Make sure the worktable is
flat and horizontal. Following environment is
required when operating: Indoor temperature: 5
℃～40℃, Max relative humidity: 80%.
3. When moving the microscope, use one hand to
hold its front base and the other hand to hold its
arm, and lay it down carefully (See the Fig. left).
★It will damage the microscope by holding
the stage, focusing knob, head or light source
when moving.
4. When working, the surface of light source will
be very hot. Make sure there is enough room for
the heat dissipating around the light source.
5. Connect the microscope to the ground to avoid
lightning strike.
6. For safety, make sure the power switch is at
“O” (OFF) and power it off before replacing the
bulb or fuse (See the Fig. left), and wait until
both the bulb and bulb holder have cooled down.
★Bulb selected only: 12V/50W Halogen bulb.
7. Wide voltage range is supported as 100~240V.
Additional transformer is not necessary. Make
sure the voltage is in this range.
8. Use the special wire supplied by our company.
2. Maintenance
(1) Wipe the lens gently with a soft tissue. Carefully wipe off the oil marks and fingerprints on
the lens surfaces with a tissue moistened with a small amount of 3:7 mixture of alcohol and
ether or dimethylbenzene.
★As the alcohol and ether is flammable, don’t place these chemical near to fire or fire
source. For example, when turning on/ off the electrical device, please use these chemical in
a ventilated place.
(2) Don’t use organic solution to wipe the surfaces of other components. Please use the neutral
detergent if necessary.
(3) If the microscope is damped by liquid when using, power it off immediately and wipe it dry.
(4) Never disassemble the microscope, otherwise the performance will be affected or the
instrument will be damaged.
(5) After using, cover the microscope with a dust cover.
3. Safety Sign
Sign Signification
The surface gets hot and don’t touch it with bare hand.
Study the instructions before use. Unsuitable operation would lead to
person hurt or instrument faulty.
| Main switch ON
O Main switch OFF
Portable
Position
Handhold
Position
Main
Switch

1
1. Components A15.0908 Series
Polarizing Microscope Components
Eyepiece
Interpupillary
Distance Indicator
E
y
e-ca
p
Diopter
Ad
j
ust
m
ent Rin
g
Epi-Illuminator
Grou
p
Upper Light
Source Group
Middle Head
Bertrand Lens
Centering Screw
Objective
Nose
p
iece
Light Adjusting
K
nob
Objective
Body
Coarse Adjusting
Limit Knob
Fine
Focusing Knob
Coarse Focusing
K
nob
Condenser
(With polarizer group)
Condenser
Up-down Knob
Up and Down
Switch
Binocular
Head

2
A15.0908 Series
Bertrand Lens
Switch Turntable
Bertrand Lens
Focusin
g
Knob
Compensator
Rotatable Stage
Ground Glass
Flashboard Grou
p
Polarizer Flashboard
Group
Stage Lock Screw
Tension
Adjustment Ring
Stage Clip
TV and Photography
Device Lock Screw
Light Path
Selecting Pole
Trinocular
Head
Condenser Center
Adjusting Screw
Condenser
Lock Screw
Field Diaphragm
Adjusting Ring
Analyzer Group
Spectroscope Pole
Color Filter Group

3
2. Assembling A15.0908 Series
2-1 Assembling Scheme
Following is the Assembling Scheme, and the numbers denote the assembling order.
★ Before assembling, make sure there is no dust or dirt. Assemble carefully and do not
scrap any part or touch the glass surface.
①
②
③
②
④
⑥
⑤
⑧
⑦
⑨
⑩
①
⑩

4
A15.0908 Series
2-2 Assembling Steps 2-2-1 Assemble and Replace the Halogen Bulb
◎For Transmitted Illumination
When assembling the halogen bulb for transmitted
illumination, hold the bulb①with clean glove or
tissue and insert the pins②into the receptacles③.
Make sure the bulb is vertical (See Fig. 1).
◎For Reflected Illumination
(1) Loosen the lock screw①with the M4 inner
hexangular spanner which is equipped with the
microscope, to take off the cover group (See Fig. 2).
(2) Open the bulb lock sheet②, hold the bulb③with
clean glove or tissue and insert the pins④into the
receptacles⑤. Make sure the bulb is vertical (See Fig.
3).
(3) Loosen the bulb lock sheet②to lock the bulb,
and put on the cover group.
★Before replacing, cut off the main power supply,
and wait until the bulb and bulb holder have
cooled down.
★Bulb selected only: 12V/50W HAL Bulb(Philips
7027).
★Don’t touch the bulb with fingers. If there is
fingerprint on it, clear it with clean tissue.
2-2-2 Assemble the Light Source Group
◎For Transmitted Illumination
Match the guide pins①of bulb base with the guide
receptacles②of microscope body, and push the light
source group into the microscope body thoroughly.
(See Fig. 4)
◎For Reflected Illumination
(1) Fully loosen the lock screw①of the reflected
illuminator. (See Fig. 5)
Fig.4
Fig.2
Fig.1
Fig.3

5
A15.0908 Series
(2) Push the light source group base②into the
reflected illuminator light source base③thoroughly,
then lock the lock screw①.
2-2-3 Assemble the Condenser (With Polarizer Group)
◎For Transmitted Illumination
(1) Rotate the coarse focusing knob①to raise stage
to the highest. (See Fig. 6)
(2) Rotate the condenser up-down knob②to move
the condenser bracket to the lowest.
(3) Loosen the condenser lock-screw③fully.
(4) Swing out the front lens of condenser④with the
scale forward. Make the lock screw⑤of condenser
in alignment with the groove⑥of the condenser base.
Push the condenser into the innermost of base.
(5) Screw down the condenser lock screw, and raise
the condenser to the highest position with the
condenser up-down knob.
2-2-4 Assemble the Stage Clip
Plug the two stage clip pins①into the hole②on
rotatable stage thoroughly. (See Fig.7)
When using the moving stage, plug the two φ3mm
forelocks into the two holes②, and lock them on
stage with M4 screws.
★ Adjust the handle to “60” reticle (to “0”) when
using the moving stage on X-axis, to avoid
hurting objectives.
2-2-5 Assemble the Objective
Rotate the coarse focusing knob to lower the stage.
Screw the 10X objective into the hole of nosepiece
with red mark, then install the objectives into the
nosepiece from the lowest magnification to the
highest in a clockwise direction. (See Fig.8)
Fi
g.6
Fig.7
Fig.5
Fig.8

6
A15.0908 Series
2-2-6 Assemble the Epi-Illuminator
(1) Loosen the lock screw①of the Epi-Illuminator
fully. (See Fig. 9)
(2) From a little right position, insert the coattail
interface on the bottom of Epi-Illuminator into the
hole on the stand with a little left inclined, and then
screw down the lock screw.
★The screw head should be pushed into the “V”
slot on the right side of Epi-Illuminator coattail
interface when locking.
2-2-7 Assemble the Middle Head
(1) Loosen the middle head lock screw①fully. (See
Fig.10)
(2) From a little right position, insert the coattail
interface on the bottom of middle head into the hole
on the Epi-Illuminator with a little left inclined, and
then screw down the lock screw.
★The screw head should be pushed into the “V”
slot on the right side of the middle head coattail
interface when locking.
2-2-8 Assemble the Head
(1) Loosen the head lock screw①fully. (See Fig. 11)
(2) From a little right position, insert the coattail
interface on the bottom of head into the hole of
middle head with a little left inclined. Keep the two
eyepiece tubes forward, and then screw down the lock
screw.
★The screw head should be pushed into the “V”
slot on the right side of the head coattail
interface when locking.
2-2-9 Assemble the Eyepiece
(1) Take down the cover of eyepiece tube①. (See Fig.
12)
(2) Insert the eyepiece②into the eyepiece tube to the
bottom.
Fig.9
Fig.11
Fig.10
Fig.12

7
A15.0908 Series
★Install the eyepiece with cross ruler into the
right eyepiece tube, and insert the square pins of
the location ring into the square groove of the
eyepiece tube.
2-2-10 Connect the Power Cord
(1) Make sure the power switch is at “O” (OFF). (see
Fig. 13)
(2) Insert the connector①of light source group into
the power socket②of the microscope.
(3) Insert the aviation plug③into the aviation socket
④of the microscope.
(4) Insert one end⑤of the power cord into the
microscope power socket⑥.
(5) Insert the other end of the power cord into the
power supply socket.
★Cancel Step 3 for Transmitted Models, while
cancel Step 2 for Reflected Models.
★Don’t use strong force when the power cord is
bended or twisted, otherwise it will be damaged.
★Use the special wire supplied by our company.
If it’s lost or damaged, choose one with the same
specifications.
★Connect the power cord appropriately to make
sure the instrument is connected to ground.
Fig.13

8
3. Operation A15.0908 Series
3-1 Set Illuminations
(1) Put through the power supply, and turn the main
swith to “|” .
(2) Move the analyzer flashboard group out of the
light path.
(3) Turn the Bertrand lens switch turntable to “0”, to
move the Bertrand lens out of the light path until a
sound of “KaDa” is heard.
◎For Transmitted & Reflected Model
(4) For transmitted illumination, set the switch②to
“”, and pull out the spectroscope pole③to
move the spectroscope out of the light path, then
adjust the light adjustment knob ①until the
illumination is comfortable for observation. (See Fig.
14, 15)
For reflected illumination, set the switch ②to
“”, and push the spectroscope pole③to the
innermost, to move the spectroscope into the light
path, then adjust the light adjustment knob①until
the illumination is comfortable for observation.
◎For Transmitted Model
(4) Adjust the light adjustment knob①until the
illumination is comfortable for observation.
◎For Reflected Model
(4) Push the spectroscope pole③to the innermost, to
move the spectroscope into the light path, then adjust
the light adjustment knob①until the illumination is
comfortable for observation.
★If using the trinocular head, push the light path
selecting pole to the innermost when observed
with two eyes.
★R represents the reflection illumination, while T
represents the transmitted illumination.
★The switch is only for the Transmitted &
Reflected Model.
Fig.14
Bright
Dark
Fig. 15

9
A15.0908 Series
3-2 Adjust Focusing
(1) Put the slice on the stage, hold it with the stage
clip. Shift the 5X objective into the light path.
(2) Loosen the coarse adjusting limit knob①, observe
the right eyepiece with the right eye. Rotate the coarse
focusing knob②until the image appears in the view
field，then lock the coarse adjusting limit knob①. (see
Fig. 16)
★The random upper limit knob can prevent the
slice from touching the objective when high
magnification objective coarse focusing, to avoid
damages to the objective or slice.
★The random upper limit knob does not react on
the fine focusing knob.
(3) Rotate the fine focusing knob③for clear details.
3-3 Adjust the Focusing Tension
If the handle is very heavy when coarse focusing or
the specimen leaves the focus plane after focusing, or
the stage declines itself, please rotate the tension
adjustment ring①as the arrow direction, to solve the
problem. (See Fig. 17)
3-4 Adjust the Diopter
After the image is clear in the right eyepiece, observe
the left eyepiece with the left eye. If the image is not
clear enough, rotate the diopter adjustment ring①
until the image is clear (See Fig. 18).
There are ±5 diopters on the diopter adjustment ring,
and the value aligned with the scale is your eye’s
diopter. The dot “·” on the left side can also indicate.
★Remember your eye’s diopter, so that you can
use it next time.
Fig.16
Fig.17
Loosen
Tighten
Fig.18
Interpupillary
Distance Indicator
Diopter Indicator

10
A15.0908 Series
3-5 Adjust the Interpupillary Distance
When using two eyes to observe, hold the bases of the
prism and rotate them around the axis to adjust the
interpupillary distance, until there is only one field of
view when binocular observation (See Fig. 19).
Interpupillary distance adjustable range: 52~75mm.
The dot “·” on the left eyepiece base points to the
scale of the interpupillary distance indicator. The
scale value is the interpupillary distance.
★Remember your eye’s interpupillary distance, so
that you can use it next time.
3-6 Use the Eye-cap
(1) Turn down the eye-cap if the user is wearing
glasses, so that it can prevent the glasses touching the
eyepieces and avoid damaging to both glasses and
eyepieces.
(2) Open the eye-cap if the user doesn’t wear glasses,
so that it can prevent stray light disturbing the
observation. (See Fig. 20)
3-7 Adjust the Objective Center
All the objective centers could be adjusted. When
adjusting, plug the two 1.5mm hexa spanners into the
hexa bolthole on the corresponding objective
nosepiece circle (see Fig. 21①). Adjust the objective
center, superpose it with the rotary center of the
rotatable stage.
Adjusting Method：
(1) Find a black dot in the image in observation, and
move the slice, in order to locate it with point “a” in
the center of cross in eyepiece. (See Fig. 22)
(2) Rotating the stage, if the objective center does not
superpose with the stage rotary center, the dot will be
away from the cross center and rotate with a circle,
the center “c” is just the rotary center of the stage.
Fig.22
Fig.21
Fig.20
Fig.19

11
A15.0908 Series
(3) Rotating the stage, turn the black dot to “b”, and
adjust the objective in order to move the dot to the
midpoint of ab, which is the center “c’.
(4) Move the slice to turn the dot from center “c” to
point “a”. Rotate the stage, to see whether it is
superposed with the cross center of eyepiece. If they
are not superposed, do the above steps again until
they are superposed.
3-8 Center the Condenser
◎For Transmitted Illumination
(1) Rotate the condenser up-down knob①to raise the
condenser to the highest position.
(2) Rotate the spanner②to move the front lens into
the light path (See Fig. 23).
★Move the front lens of the condenser into light
path when use the objective beyond 20X.
(3) Rotate the 20X objective into the light path and
focus the specimen.
(4) Rotate the field diaphragm adjustment ring③to
put the field diaphragm to the smallest position. Then,
the image of field diaphragm can be observed in the
eyepiece.
(5) Rotate the condenser up-down knob, to adjust the
image to be clearest.
(6) Adjust the condenser center adjustment screw④
and move the image to the center of the view field.
(7) Open the field diaphragm gradually. If the image
is in the center all the time and inscribed to the field
of view, it shows condenser has been centered
correctly (See Fig.24).
(8) In actual use, enlarge the field diaphragm a bit and
make the image circumscribed to the field of view.
Fig.23
Fig.24

12
A15.0908 Series
3-9 Adjust the Field Diaphragm
By limiting the diameter of light entering the
condenser, the field diaphragm can prevent other light
and strengthen the image contrast. When the image is
just on the edge of the field of view, the objective can
perform best and obtain the clearest image.
◎For Reflected Illumination
(1) Turn the field diaphragm turntable ①to the
lowest, to minimize the field diaphragm (See Fig. 25).
(2) The image of field diaphragm can be observed in
the view field through eyepiece.
(3) Plug the two M4 hexa spanners into the left and
right field diaphragm centering bolthole②, until the
image is adjusted to the center.
(4) Open the field diaphragm gradually, if the image
of field diaphragm is inscribed with the field of view,
then the field diaphragm is centered correctly (See Fig.
26).
(5) In actual use, enlarge the field diaphragm a little,
to make its image circumscribed to the field of view.
◎For Transmitted Illumination
Rotate the field diaphragm adjustment ring ③in
clockwise, to enlarge the field diaphragm; otherwise,
to decrease it in counterclockwise. (See Fig. 23)
3-10 Adjust the Aperture Diaphragm
The aperture diaphragm decides the numerical
aperture of the illumination system. If the N.A. of
illumination system matches with the N.A. of the
objective, it can obtain better resolution and contrast,
and increase the depth of field.
As the contrast of microscopic samples is usually low,
it is advised to adjust the diameter of aperture
diaphragm to be 70%-80% of the N.A. of objective (it
is allowed to take down the eyepiece and observe
through the eyepiece tube). In actual use, adjust it on
the basis of good contrast and comfortable
observation.
Fig.26
Fig.25

13
A15.0908 Series
◎For Reflected Illumination
The changing direction of the aperture diaphragm is
as same as the field diaphragm, adjust its size by the
aperture diaphragm turntable ①. Adjust the two
aperture diaphragm centering screws②, to move the
image of aperture diaphragm to the center of the
aperture (See Fig. 27).
◎For Transmitted Illumination
Change the size of aperture diaphragm by turning the
aperture diaphragm adjusting ring①. (See Fig. 28).
Use of graduation: Put the N.A. of condenser to the
80% of the N.A②of objective.
3-11 Adjust the Analyzer
(1) Insert the analyzer flashboard①upward into the
socket of the intermediate lens group until to the
innermost, and the analyzer is shifted into the light
path. (See Fig. 29)
(2) Loosen the lock screw ④, turn the analyzer
turntable②, to change the vibrated direction of the
analyzer. A grid value of scale is 2°, and the adjusting
range is 360°. When observed orthogonally, the “0”
reticle on turntable②should be leveled with the “0”
reticle on the vernier③. A grid value of vernier is 6′.
3-12 Adjust the Polarizer
◎For Reflected Illumination
(1) Insert the polarizer flashboard④forward into the
socket of illumination system. The polarizer is moved
into the light path until two sounds of “KaDa” is
heard. (See Fig. 29)
◎For Transmitted Illumination
(1) Turn the polarizer adjusting ring①, to adjust the
vibrated direction of the polarizer which is 360°
rotatable. When observed orthogonally, the “0” reticle
on adjusting ring should be leveled with the reticle on
the base. (See Fig. 30)
Fig.29
Fig.30
Fig.27
Fig.28

14
A15.0908 Series
3-13 Check H-V Location
The system will be in H-V location when both the
analyzer and polarizer are adjusted to “0”. In addition,
it could be checked under the method as following: no
specimen on the stage, take off the eyepiece and the
objective, move the Bertrand lens out of the light path,
adjust the analyzer to “0”, and rotate the polarizer
ajustment ring, observe the brightness changing of
view field from the eyepiece tube, the system is in
H-V location when it is the darkest. At the same time,
the polarizer should be almost levelled to “0”.
★For orthogonal polarization observation, insert
the analyzer other than Bertrand lens, and make
the vibration direction of polarizer be vertical with
the analyzer.
3-14 Use the Compensator
The compensator①is inserted into the slot②of the
middle head in 45° declined. The surface with
alphabetic character is upwards, the λ, λ/4 and
dustproof board should be inserted thoroughly, and
the quartz chock can be inserted if necessary. (See Fig.
31)
3-15 Use the Rotatable Stage
Rotatable stage is a high accuracy component, which
cannot stand the impact and the user should turn it
gently. The surface has been printed with wearable
plumbaginous coat. A grid value of scale on stage is
1°, a grid value of vernier is 6′. The stage cannot turn
when the lock screw is locked.
3-16 Use the Color Filter
The color filter can make the background light more
suitable and strengthen the image contrast (See Fig.
32).
Fig.32
Fig.31

15
A15.0908 Series
There are four colors of filter selectable: bule, green,
yellow and white.
★Place the filter’s rough side downwards.
3-17 Replace the Fuse
Turn the main switch to “O” (OFF) before replacing
the fuse. Pull out the power cord. Then screw off the
fuse group①from the fuse base②with a “-” type
screwdriver. Install a new fuse and screw it in the fuse
base (See Fig. 33).
★Specification of the fuse: 250V, 3.15A.
3-18 Use the Bertrand Lens
(1) Move the high magnification objective (50X) into
the light path, and set the polarizer and the analyzer in
the H-V location. (See Fig. 34)
(2) Put in the slice (as Mica), then turn the coarse and
fine focusing knobs until the image is clear.
(3) Rotate the Bertrand lens switch turntable①, locate
it on position “B”, to move the Bertrand lens into
light path. At that time, the “black cross” can be seen
in the eyepiece, which is the interference pattern.
(Turn the stage to observe.)
★It should use 20X or above objective when using
Bertrand lens.
★Normally, Bertrand lens is suitable to be used in
transmission light.
(4) Adjust the Bertrand lens centering screw ②
(turning both left and right sides at the same time), to
move the interference pattern to the center of the view
field.
(5) Turn the aperture diaphram adjusting ring on
condenser group, to enlarge the aperture diaghram.
(6) Turn the Bertrand lens focusing screw③, to adjust
the interference pattern to be clearest.
Fig.34
Fig.33

16
A15.0908 Series
★Conoscopic observation is based on the
orthogonal polarization observation, add the
Bertrand lens, i.e. the polarizer, analyzer and
Bertrand lens are in the light path at the same
time.
3-19 Use the Trinocular Head, TV and Photography
Device
3-19-1 Select the Light Path
For the trinocular head, the light path selecting pole
①can control the optical energy ratio for
binocular and three-links. Push the light path
selecting pole to the innermost, the light all comes
into the binocular head. Pull the light path selecting
pole to the outermost, the ratio of binocular and
three-links is 5:5. Usually, push the light path
selecting pole to the innermost for binocular
observation, pull the light path selecting pole to the
outermost for trinocular observation (TV and
photography). (See Fig. 35)
3-19-2 Assemble and Use the TV Device
(1) Loosen the lock screw①of trinocular head,
take out the dust-cover②. (See Fig. 36)
(2) Take down the dust-cover of the TV adapter③.
Insert the TV adapter into the trinocular head
according to the figure and screw down the lock
screw①.
(3) Loosen the lock-screw④of the TV adapter.
Take down the vidicon interface (C type) ⑤from
the TV adapter, and screw in the CCD or vidicon.
Then install the interface with CCD or vidicon into
the TV adapter, and screw down the lock-screw④.
(4) Do binocular observation, after the image is
clear, pull the light path selecting pole⑥to the
outmost and observe the image. If the image is
unclear, rotate the adjustment tube⑦to focus,
until it is clear.
Fig.36
Fig.35

17
A15.0908 Series
3-19-3 Assemble the Photography Device
(1) Loosen the lock screw①of trinocular head,
take out the dust-cover②. (See Fig. 37)
(2) Insert the photography device into the trinocular
head as shown in the figure, and screw down the
lock screw①.
(3) Loosen the lock-screw③of the photography
adapter and take down the photography adapter④
(See Fig. 38).
(4) Insert the 3.2X photography eyepiece⑤into
the eyepiece base ⑥, install the photography
adapter④and tighten the lock-screw③.
(5) Do binocular observation, after the image is
clear, pull the light path selecting pole⑦to the
outmost, then operate the photography device
according to its instructions.
3-20 Use the Digital Viewing Head
3-20-1 Connect the Power Cord
Insert the output connector of the transformer into
the power socket②on the back of the head, insert
the video cable into the C-Video video output
port/USB port③on the back of the head. (See Fig.
39)
★When using the digital viewing head, the
power supply is provided by USB.
3-20-2 Signal Output
Pull the light path selecting pole①of viewing
head to the outmost, which can do projection of
both the binocular and TV at the same time, with
the light ratio of 80:20. Push the light path selecting
pole to the innermost, 100% of the light can enter
the binocular observation system. (See Fig. 39)
Fig.37
Fig.38
Fig.39