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OPERATING THE HITACHI S-900

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OPERATING THE HITACHI S-900 Powered By Docstoc
					HITACHI S-900 OPERATING INSTRUCTIONS                                           Rev1.0

                         HITACHI S-900 OPERATING INSTRUCTIONS

These operating instructions are intended as a basic guide for Users of this laboratory and
are periodically updated. The Electron Microscope Unit provides suitable training on the
safe use of this instrument and any ancillary equipment.

RULE 1:          DON'T TOUCH A CONTROL IF YOU ARE NOT SURE OF
                 THE OUTCOME OF THAT ACTION
RULE 2:          NEVER, EVER FORCE ANYTHING BEYOND FINGER STRENGTH
RULE 3:          IF IN DOUBT ASK FOR HELP


Contents

Normal Standby Condition
Switching on From Standby
Ant contamination Trap
Switching off the S-900
Removing a Specimen
Inserting a Specimen
Obtaining an Image
Photo Recording
Exposing Two Different Images on the Same Film
Low Magnification Mode
Correcting Astigmatism with the Dynamic Stigmator
Automatic Focus (AFC)
Differential Image and Gamma Control
Dual Mag/Split Screen Display
Brightness and Contrast Control
Dynamic Focus
Low Magnification Mode
Operation at Low Accelerating Voltages (1-5 kV)
Operation of Beam Monitor System
Raster Rotation – Tilt Compensation Unit
Additional S 900 Notes for Experienced Users


NORMAL STANDBY CONDITION

The S-900 FESEM, when not in use, is left:

       1         with all the vacuum pumps running
       2         with the Specimen Chamber (SC) airlock valve CLOSED.
       3         with the DISPLAY POWER switch OFF
       4         with the specimen holder fully inserted into the microscope


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HITACHI S-900 OPERATING INSTRUCTIONS                                             Rev1.0

SWITCHING ON FROM STANDBY

1.     LOGIN: Logon to the local client network using your login name and password

2.     Turn on DISPLAY POWER. Scan lines will appear on the visual displays in about 15 sec.
       A warning buzzer will sound if the cooling water is not turned on.

ANTICONTAMINATION TRAP

1.     The S-900 FESEM is particularly good at voltages below 5 kV. But at low voltages the
       effect of contamination (typically a dark square you notice when you go to lower
       magnifications) is more obvious. Always start your session by topping up the high vacuum
       trap and the specimen anti contaminator with liquid nitrogen.

2.     The high vacuum trap, located just above the turbo molecular pump, is to be filled through a
       funnel and tube to the left of the column. It has a capacity of 2 Litres of liquid nitrogen.

Specimen Anti contaminator
1.    Loosen the locking screw for the liquid nitrogen container of the anti contamination trap.
2.    Turn the liquid nitrogen container clockwise.
3.    Lower the liquid nitrogen container.

Attachment of Anti contamination Trap
1.    Ease the liquid nitrogen container into place with the notch toward you, and then turn the
      container counter clockwise.
2.    Fasten the liquid nitrogen container with the locking screw.

SWITCHING OFF THE S-900

1.     Press the HV READY/OFF switch to turn off the kV.

2.     Set to Close the SC AIRLOCK VALVE.

3.     Remove your specimen. GENTLY retighten the specimen clamping screw and reinsert the
       specimen holder into the microscope to keep it clean.

4.     Turn off the DISPLAY POWER switch on the evacuation panel.

                        DO NOT TURN OFF ANY OTHER SWITCHES

5.     Logout of the local client network

6.     Turn off the room lights and close the door after you.

REMOVING A SPECIMEN


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HITACHI S-900 OPERATING INSTRUCTIONS                                               Rev1.0

1.     In the S-900 the specimen is mounted on brass plates 11 x 5 mm which clamps into the end
       of a specimen insertion rod or specimen holder. The rod can be rotated to tilt the specimen
       (single-tilt holder).

2.     To keep the rod safe and clean it is stowed when not in use in the microscope.

3.     To get the holder out:
       .1      Pull the holder knob about 25mm to its stop
       .2      Rotate 15 o counter clockwise to stop
       .3      Pull out another 30 mm to stop
       .4      Rotate 180o counter clockwise to stop
       .5      Turn the airlock pump switch to AIR
       .6      The rod relaxes 2 mm out of the airlock
       .7      Without turning it, pull the rod straight out of the airlock




4.     The standard stage in the S-900 is a single tilt eucentric stage designed so that when the
       specimen is being tilted it does not disappear from view or go out of focus. In practice the
       alignment is never perfect so some
       movement and defocusing usually occurs
       during tilting though you should never
       lose sight of the centre of the field.

5.     To achieve this, the top of the specimen
       must lie on the tilting axis (= insertion rod
       axis). To allow specimens of different
       heights to be accommodated in the stage,
       the stage has jaws notched to hold the
       specimen plates at three different levels.
       Entirely flat specimens are clamped in the
       top notches, specimens 2.5 mm high are
       clamped in the bottom notches and
       intermediate height specimens in the
       centre notches.

6.     For easy loading of the holder, the
       loading jig has a screw to elevate the
       specimen plate into position between the
       correct level of notches. When the plate
       is in the right position, the right hand
       movable jaw can be slid to grasp the plate, and the clamping screw can be tightened to hold
       everything firm.

       THE SCREW HAS A SLENDER STEM AND IS ONLY BRASS SO YOU CAN

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HITACHI S-900 OPERATING INSTRUCTIONS                                                Rev1.0

       EASILY SNAP ITS HEAD OFF! DO NOT OVER TIGHTEN.

7.     Remember the FESEM is a high resolution instrument and it is accordingly sensitive to dirt
       and contamination. Finger grease will contaminate specimens if you touch the metal of the
       insertion rod with bare fingers. Any grease on the insertion rod should be wiped off with a
       tissue dampened with acetone.


 CAUTION               If the specimen plate falls out of the insertion rod during insertion
                       into the microscope it will cause much trouble and may damage the
                       delicate airlock. You will lose your session and spoil the day for
                       others. You MUST take all precautions to see the specimen plate is
                       properly fixed. Before inserting the insertion rod into the airlock,
                       check carefully that the specimen plate is correctly located between
                       matching notches. Turn the insertion rod upside down and poke the
                       back of your specimen hard with your forceps to test that it is firmly
                       clamped.


INSERTING A SPECIMEN

1.     Line up the insertion rod with the airlock and the pin with the keyway and slide the rod in
       without touching the side, if you can. DO NOT ROTATE THE ROD YET.

2.     Switch the airlock from AIR to EVAC. and pump for 20-30 sec until the green light comes
       on.

3.     Rotate the rod clockwise half a turn to a stop and press it in 30 mm to a stop.

4.     Rotate another 15 deg. to a stop and let the rod slide in 25 mm to the operating position.

OBTAINING AN IMAGE

1.     When the SC VACUUM HIGH lamp is green open the S.C. AIR LOCK VALVE (V-1).

2.     Are video control SE switch and IMAGE SIGNAL SELECTOR in position SE?

3.     Select Accelerating voltage. Use the left two rotary selector switches to select a voltage
       between 1 and 30 kV e.g. [0][1] or [3][0]. Set the right rotary selector to [2] for flashing.
       The accelerating voltage may be varied in 100 V increments for special applications - see
       notes for experts or the manual.

       Note:          If the specimen is conductive and does not require coating, the accelerating
                      voltage can be decided at the microscope. You can even vary the voltage to
                      find a voltage at which the specimen does not charge. Non-conductive or
                      low density specimens have to be given a coat no thicker than the resolution

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HITACHI S-900 OPERATING INSTRUCTIONS                                               Rev1.0

                      required, e.g. to resolve 2 nm particles the coat must be about 2 nm. The
                      accelerating voltage is then matched to the metal coat thickness in the ratio
                      of 1kV per nm; e.g. 2kV for 2 nm of chromium coating.

4.     Push HV ON SWITCH. The HV will not come on unless the READY OFF lamp is lit
       green. The HV ON lamp lights up upon pressing the switch. The extracting voltage (V1)
       increases until the emission current stabilises at 10 µA. Normal values for extracting
       voltage are between 3 (very good) and 6.5 (emitter tip needs changing). If the emission
       current falls too much below 10 µA the image will become noisy. To increase the beam
       current, press the HV ON SWITCH again. The HV ON SWITCH automatically flashes
       red to alert you that current is low, so if it flashes, press it (unless in the middle of an
       exposure).

5.     The COND LENS control default setting is 5. At 5, the spot on the specimen is small
       enough for imaging at 400,000x, and there is enough current always in the spot that noise is
       low enough for use at any magnification. So it is convenient and advised to leave the
       COND LENS at 5. For higher settings 6, 7, then reduce electron probe current without
       improving resolution.

6.     Check the BEAM MONITOR switch is ON and depress the BMC switch. If the BMC
       switch starts to flash during operation, press it again, except during photo recording, when
       you should wait till the photograph finishes.

7.     Set the INVERT/MANUAL/AUTO switch to AUTO and press the ABC button. In a few
       seconds (10 sec at maximum) the Automatic Brightness and Contrast circuit adjusts image
       brightness and contrast to optimum.

       Note:          Depress the ABC switch any time to optimise image appearance and especially
                      just before recording a micrograph. You may need to press ABC several times
                      on start-up or after a large alteration in e.g. condenser setting. You may
                      alternatively set the INVERT/MANUAL/AUTO switch to MANUAL and use
                      the CONTRAST and BRIGHTNESS knobs, monitoring the effect either with the
                      red/green LED displays under the screen or with the Video Line Scan display.
                      When the INVERT/MANUAL/AUTO switch is set at AUTO, the CONTRAST
                      and BRIGHTNESS displays will not function and the manual CONTRAST and
                      BRIGHTNESS controls have no effect.

8.     Depress the MAGNIFICATION switches to select a magnification of 250 to 1000x.

9.     Depress the STD POSIT. switch and adjust focus by the Z control of the specimen
       goniometer stage. With this operation, specimen height is set at the standard position
       (eucentric position) in which image centre should stay in view during tilting.

10.    Depress the STD POSIT. switch again to release its function.

11.    Adjust the FOCUS COARSE control to focus the image. Over 50,000x use the MID or

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HITACHI S-900 OPERATING INSTRUCTIONS                                               Rev1.0

       FINE control. The AFC coarse and fine Auto Focus Controls work well for beginners.
       Reduced raster fast and slow scan rates are good for adjusting focus. If the centre of the
       image moves around during focussing, the aperture should be adjusted to minimise
       movement with focus change.

12.    At lower magnifications, scan the specimen using the rollerball to control the X and Y
       position of the specimen stage. At higher magnifications, select visual field by the IMAGE
       SHIFT (X, Y) controls.

13.    Choose a magnification for observation, double it for correcting focusing and astigmatism,
       then drop back for observation and recording.

14.    As with any SEM, sharpness in the image depends on correct adjustment of both Focus and
       Astigmatism. There are three levels of sensitivity of focus adjustment and two levels of
       astigmatism adjustment. The controls should be used in the sequence Focus Stigmator X
          Stigmator Y Focus Stigmator x, etc until no further improvement can be made.

PHOTO RECORDING

1.    Before you start, decide what photographic format suits your purpose best. There are three
camera backs to choose from.

       Note           You may save high resolution images digitally for computer processing and
                      publishing via the ImageSlave personal computer system while recording
                      images to film or as an alternative to film.


2.     The Polaroid 45 takes single positive only exposures on 100 mm x 125 mm Type 52
       instant film.

3.     The Polaroid 106 back takes an 8 pack of 86 mm x 108 mm Positive/Negative Type
       665 instant film which gives an instant positive and also a negative for further copies.

4.     The roll film back takes 10 exposures 60 mm x 80 mm per roll of Agfa APX 100 film
       which has to be developed and printed before you can see your images.

The films in use have different speeds. Exposure is adjusted using the camera aperture. e.g.


 FILM                                          FILM SPEED                 APERTURE
 Agfapan APX 100                               100 ISO                    f 4 (max)
 Polaroid Positive/Negative Type 665           80 ISO                     f4
 Polaroid PolaPan Type 52 4x5in                400 ISO                    f8


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HITACHI S-900 OPERATING INSTRUCTIONS                                                Rev1.0


5.     Select image field and focus the image.

6.     Press SCANNING SPEED switch [1] to deselect fast scan.

7.     Set the Invert/Manual/Auto switch to AUTO and press the ABC button.

8.     Check the left-side PHOTO SCANNING SPEED switch is set to [2] (80 sec).

9.     Confirm that film is loaded in the camera, and the DARK SLIDE is removed from the
       camera then depress the PHOTO switch. While photographing, the PHOTO switch
       lamp (red) is lit.

10.    When the photo frame scan ends, a buzzer sounds and the image observation mode is
       automatically resumed.

TO EXPOSE TWO DIFFERENT IMAGES ON THE SAME FILM

1.     To superimpose two exposures of different image signals on the same film (e.g.,
       secondary electron image plus overlay of a line analysis or line position indicator,)
       proceed as follows.

       .1        Photograph the first CRT image by the procedures in PHOTO RECORDING
                 above.

       .2        After the PHOTO lamp (red) goes out and the buzzer has sounded, select a
                 different signal. When overlaying a line analysis signal, depress the
                 SCANNING MODE LA switch and then the PHOTO switch.

       .3        The second exposure is completed when the PHOTO lamp goes out and the
                 buzzer sounds.

       .4        When adding an overlay exposure of line analysis position, for example,
                 depress the POSITION SET and PHOTO switches. A line indicating the
                 analysing position is recorded on the same film. As before, the exposure is
                 completed when the PHOTO lamp goes out and the buzzer sounds.

       .5        Overlay images of other signals such as x-ray dot maps or x-ray line scans can
                 be recorded by the same method.

LOW MAGNIFICATION MODE

1.     Depress the LOW MAG. switch on the option panel. This operation sets a
       magnification of 100x which can be varied with the magnification buttons.

2.     Adjust focus by the FOCUS COARSE control (fine & medium are disabled).

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HITACHI S-900 OPERATING INSTRUCTIONS                                                Rev1.0


3.     Correct astigmatism with the STIGMA RESET (X, Y) controls on the blind panel.

4.     To return to high magnification mode, depress the HIGH MAG. switch on the option
       panel.

CORRECTING ASTIGMATISM WITH THE
DYNAMIC STIGMATOR MONITOR (DSM)

1.     Increase magnification to a few thousands.

2.     Depress the DSM switch. A crisscross mark appears on the CRT.

3.     Adjust blur of the image by operating the AMPLITUDE control according to the
       selected magnification.

4.     Adjust the STIGMATOR (X, Y) controls so that the focused portion of the image is
       positioned at the crisscross mark.

5.     Depress the DSM switch again to reset the usual scanning mode.

6.     Tweak the FINE FOCUS and the STIGMATORS for final perfection.

AUTOMATIC FOCUS (AFC)

1.     Press the AFC switch. Ordinarily, the CRT image disappears for a few seconds, then a
       buzzer sounds and the focused image is displayed.

2.     Use the AFC COARSE switch when the profile of an image cannot be seen at all, and
       use the AFC FINE switch when you can see some vague detail in the image.

3.     There are two kinds of buzzer sounds at the end of Auto Focus operation. The longer
       buzzer sound indicates that the operation has been completed, while the shorter sound
       means that the normal operation is impossible because the contrast is too strong. In the
       latter case, reduce the contrast level.

The Auto Focus Control works poorly when:

1.     The signal is too weak so the image is not clear at the full-frame rapid scan rate.

2.     There is excessive charging artefact on the specimen.

3.     The specimen has little structural detail. (For example a silicon wafer.)

The Auto Focus will not work at all when:


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HITACHI S-900 OPERATING INSTRUCTIONS                                              Rev1.0

1.     Low magnification mode is set.

2.     The INT. LENS switch on the alignment panel is turned off.

3.     The APT. ALIGN. switch on the alignment panel is turned on.

DIFFERENTIAL IMAGE AND GAMMA CONTROL

Differential image
1.     This is used for emphasising the edges in an image. [0] indicates OFF, and the effect of
       differentiation increases as you increase from [1] through to [3].

2.     Note that brightness of the differential image cannot be changed by the BRIGHTNESS
       control. (For adjustment of brightness, use the VIDEO LEVEL control on the blind
       panel.)

Gamma Control
Used for levelling out contrast in an image which has an area where contrast is extremely
strong. [0] indicates OFF, and the effect of gamma increases as you increase from [1] through to
[3].

Gamma control is effective even when the ABC (automatic image adjustment) is operated.

DUAL MAG/SPLIT SCREEN DISPLAY

Simultaneously displays a high and a low magnification image of a specimen on two CRTs or
the upper and lower halves of a single CRT.

1.     Turn the HIGH MAG ONLY/DUAL MAG switch at DUAL MAG.

2.     Depress the DM switch. The magnification ratio of the second image is changed in the
       sequence 1...2...5...10...1..2... by pressing the switch.

3.     A white frame on the low magnification image shows the field selected for
       magnification. The selected field can be moved around the low magnification image by
       the POSITION (X, Y) controls.

4.     When the HIGH MAG ONLY/DUAL MAG switch is set at HIGH MAG ONLY, the
       two CRTs display the high magnification image.

5.     By depressing the SPLIT switch, CRT screen is divided into upper and lower halves.
       Each half is capable of independent image display (of the same specimen).

7.     When displaying different-signal images on the upper and lower halves, set the
       LOWER FIELD IMAGE switch at CH2. Then the upper half of the left-side CRT
       displays the image selected on the CH1 side of the IMAGE SIGNAL SELECTOR

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HITACHI S-900 OPERATING INSTRUCTIONS                                                    Rev1.0

         switch, and the image selected on the CH2 side of the switch is displayed on the lower
         half.

8.       When the LOWER FIELD IMAGE switch is initially set at CH2 reset the switch to
         CH1 and then set it back at CH2.

BRIGHTNESS AND CONTRAST CONTROL.

1.       The ABC - automatic brightness control - may not always give the effect you wish. In
         this case you should switch to MANUAL and use the CONTRAST (first) and
         BRIGHTNESS (next) to adjust the image.

2.       To provide a guide to setting, there are CONTRAST and BRIGHTNESS LED colour
         bar indicators on the display panel. 1

3.       Turn the controls so that the CONTRAST and BRIGHTNESS indicators are positioned
         at a mid-point.

4.       Alternatively, you may select LA (Line Analysis) to show the amplitude of the video
         signal. When set for photo recording the video signal mean should be half way up the
         display tube. The peaks should be about 25 mm above this and the black level should be
         25mm below.

DYNAMIC FOCUS

1.       In a tilted specimen, the depth of field of the objective lens is too shallow for all of the
         surface to be in focus; some will be below the zone of focus and some above, so only a
         narrow band of the visual field is focused. The dynamic focus function changes the
         focal length of the objective lens in synchronisation with electron beam scanning so as
         to obtain a focused image of the entire specimen surface.

2.       Match the tilting direction (+/-) of the specimen goniometer stage with the setting [+/-] of
         the DYNAMIC FOCUS switch on the blind panel.

         Note           Caution - The BRIGHTNESS and CONTRAST meters have been adjusted in
                        accordance with the film speed of the film used by the customer at the time of
                        installation so that they produce a good image with the PHOTO SCANNING
                        SPEED setting switch at [2] and the IMAGE SIGNAL SELECTOR switch at
                        SE. To adjust exposure, use the camera aperture.

     1
    (Caution) The BRIGHTNESS and CONTRAST meters have been adjusted in accordance with the
film speed of the film used by the customer at the time of installation so that they produce a good
image with the PHOTO SCANNING SPEED setting switch at [2] and the IMAGE SIGNAL SELECTOR
switch at SE.
To adjust the exposure use the camera aperture.



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HITACHI S-900 OPERATING INSTRUCTIONS                                                Rev1.0


3.     With the DYNAMIC FOCUS switch on the operation panel turned on and the
       DYNAMIC FOCUS control next to the switch turned to zero, adjust the FOCUS
       control of the display unit so that the image is in focus at about the centre of CRT and is
       out of focus evenly on the upper and lower sides.

4.     Turn the DYNAMIC FOCUS control so that the entire image is sharply focussed.

LOW MAGNIFICATION MODE (10x to 500 x)

1.     Depress the LOW MAG. switch on the option panel. This operation sets a
       magnification of 100x and can be varied using the magnification buttons.

2.     Focus with the FOCUS COARSE control.

3.     Correct astigmatism with the STIGMA RESET (X, Y) controls on the blind panel.

4.     For changeover from low to high magnification mode, depress the HIGH MAG. switch
       on the option panel. This operation resets the magnification to 250x.

Note The visual fields in the high and low magnification modes may differ from each other.
The visual field in the low magnification mode can be aligned with that in the high
magnification mode with the ALIGNMENT (X, Y) controls on the blind panel.

OPERATION AT LOW ACCELERATING VOLTAGE (1-5 kV)

Alignment
Alignments are seldom needed for the electron gun, condenser lens and intermediate lens.
However, when an accelerating voltage of less than 5 kV is used, the electrostatic collection
field of the secondary electron detector deflects the beam. This effect is neutralised by the low
acceleration voltage compensator located behind the column on the right. To insert the
compensator, pull the knob a little, turn it 45 degrees clockwise, and let it in gradually. When
using accelerating voltages over 6 kV pull the compensator out of the column as far as it will go
and latch it there by turning it 45 degrees anticlockwise.

At 1 kV performance is much more affected by misalignment. A general alignment of the
column is recommended for work at 1 kV and below. See below for details.

Chromatic Aberration Compensation
The FE electron gun consists of the cathode which emits electron beam, first anode to which the
extracting voltage is applied and second anode to which the accelerating voltage is applied.
The first and second anodes work as electrostatic lenses, and have a field chromatic aberration.
The lower the accelerating voltage (especially 2 kV or less), the larger the field chromatic
aberration will be. The aberration is directional and it appears like astigmatism on the image.
The field chromatic aberration will reduce the resolution when the accelerating voltage is low,
but can be offset by a reverse polarity field chromatic aberration obtained by slight

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HITACHI S-900 OPERATING INSTRUCTIONS                                              Rev1.0

misalignment of the objective aperture.

1.     Turn ON the APT ALIGN switch and align the objective lens movable aperture (at the
       current centre).

2.     Correct astigmatism at a magnification of about 20,000 to 50,000x.

3.     Increase the magnification to about 100,000x, and then carefully align the objective
       aperture until the image is at sharpest focus.

4.     Correct astigmatism, and then focus the image again.

OPERATION OF BEAM MONITOR SYSTEM

The beam monitor of the Model S-900 consists of the beam monitor aperture (detector A, for
Voltage <5kV) and the movable objective aperture (detector B for Voltage >5kV) and a selector
unit. If the wrong detector is selected a lateral stripe may appear on an image.

CAUTION            When the beam monitor aperture or movable objective aperture is
                   set at the off-axis position or withdrawn (position 0) for axial
                   alignment of the main unit, etc., it will produce a misleading
                   signal for the compensator, so the BEAM MONITOR switch on
                   the operation panel must be turned off.

At accelerating voltage 1 to 5 kV
1.     Turn the switch of the selector unit to A.
2.     set beam monitor aperture No. [3] or [4].
3.     Align the aperture axis and operate the beam monitor as described in ALIGNMENT.
At accelerating voltage 6 to 30 kV
1.     Turn the switch of the selector unit to B.
2.     For axial alignment of the movable objective aperture, turn off the BEAM
       MONITOR switch on the operation panel.

Between 6 and 10 kV choose whichever setting of the selector unit that does not produce a
lateral stripe on the image.

RASTER ROTATION - TILT COMPENSATION UNIT

Raster rotation
Raster rotation rotates the CRT image around the CRT centre by rotating the scanning pattern
(=raster) the electron beam makes on the specimen. The specimen itself does not rotate!
Raster rotation can be used for the following purposes:-

1.     Rotating the image to fit an object into the rectangular film format.


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HITACHI S-900 OPERATING INSTRUCTIONS                                                Rev1.0

2.     Selecting the line analysis direction in the line analysis mode.

3.     Making the tilt direction of the specimen coincide with the Y-axis scanning direction
       when using the tilt compensation function described below.

To Operate Raster Rotation
1.    Turn on the ROTATION switch. DO NOT use with the fast scan rate.

2.     The angle scale of the ROTATION knob indicates the angle between the tilt direction
       of the specimen (moving the stage in the Y- direction) and the Y-axis scanning direction
       of its image being displayed on CRT (that is, the vertical direction).

CAUTION               The compensatable specimen tilt angle is 0o to 70o
                      Tilt compensation is effective for flat-surfaced specimens only.
                      An unnatural image may appear if the specimen has a topographic
                      surface profile.
                      Keep the TILT COMPENSATION switch turned off without fail in
                      ordinary use.

Tilt Compensation
       The magnification in a scanning electron microscope is lower the further the specimen is
       from the final lens, because of the geometry of the scanning beam. On a tilted
       specimen, this results in distortion of magnification, and parallel vertical lines will
       appear to converge in the direction furthest from the lens. The tilt compensation
       function compensates the amplitude of the line scan as it moves from top to bottom to
       obtain an image identical to that obtained by observing the untilted specimen.

1.     Align the Y axis of the specimen goniometer stage with the Y axis scanning direction of
       the image on the CRT.

2.     Set the TILT COMPENSATION knob to the specimen tilt angle.

ADDITIONAL S 900 NOTES FOR EXPERIENCED USERS

VARYING THE ACCELERATING VOLTAGE
BETWEEN 1 AND 5 KV IN 100 VOLT STEPS.

1.     Set the FLASHING intensity setting switch at any of [4], [5], [6], or [7] to select this
       mode.

2.     FLASHING intensity setting switch [4] then corresponds to setting [0] in normal
       mode, [5] = [1], [6] = [2] and [7] = [3]. So to flash in the 100V increment mode, select
       [6], then turn back to [4] on completion of flashing.

3.     Accelerating voltage the lowest digit of the HV selector switch setting now represents a
       unit of 100 V or 0.1 kV. When selecting 1.4 kV for example, set the HV selector switch

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HITACHI S-900 OPERATING INSTRUCTIONS                                                   Rev1.0

       at [1][4].

ALIGNMENT

In theory there is an optimal column alignment for each accelerating voltage and if you wish to
attain peak resolution at maximum magnification the column alignment should be optimised for
the conditions you require. But for everyday use we manage with one default alignment for the
range 2 - 30 kV and a low voltage alignment for 1 kV and below. So when you want to use the
S-900 below 2 kV, realignment of the electron gun, condenser lens and intermediate lens is
advised which then has to be reset when changing accelerating voltage back over 5 kV.

LOW VOLTAGE SHIELD
At low voltages the voltage on the secondary electron detector can deflect the scanning beam.
A shield, with controls located at the right rear of the column, is provided to neutralise this
effect. The shield can be used for any voltage below 5 kV but it is essential for voltages of 2
kV and below. Before alignment for low acceleration the shield must be inserted into the
column.

To insert the shield, pull the knob out a little, turn it 45o clockwise, and ease the shield
gradually into the column.

When an accelerating voltage of 6 kV or higher is employed, ease the shield out of the column
to its limit, turn the knob 45o counter clockwise and ease the knob back into its retracted
position.

ELECTRON GUN

1.     Turn off BEAM MONITOR switch
       Pull out the upper beam monitor aperture and objective lens aperture
       (set the OPENING selector at [0]).

2.     Display an image at 250x in the high mag. mode.
       Adjust brightness and contrast.

3.     Turn the COND LENS control to [0].

4.     On the alignment panel:
       .1     Turn OFF the INT. LENS and ALIGN. COIL switches.
       .2     Turn ON the APT. ALIGN switch.
       .3     Keep the alignment panel switches like this for both gun and condenser lens
              alignment.
       .4     Adjust contrast to display a circular bright image on the CRT.
       .5     Align the electron gun to centre the image on the CRT.




Issued 9/15/05                                                                                 14
HITACHI S-900 OPERATING INSTRUCTIONS                                            Rev1.0

CONDENSER LENS ALIGNMENT

1.     Turn the COND LENS knob to [5]
       On the alignment panel:
       APT. ALIGN = ON
       ALIGN COIL = OFF
       INT LENS = OFF

2.     A circular bright image appears on the CRT. Check the magnification and contrast.
       Align the condenser lens to centre the image on the CRT.

3.     Turn OFF the APT. ALIGN switch on the alignment panel.

INTERMEDIATE LENS ALIGNMENT

1.     Turn ON the INT. LENS switch.

2.     Turn the DYNAMIC FOCUS/APT ALIGN switch to APT ALIGN, then adjust the
       intermediate lens with the alignment screws so that the CRT image blurs concentrically.

3.     Return the DYNAMIC FOCUS/APT ALIGN. switch to neutral.

4.     Turn ON the ALIGN. COIL switch.

MOVABLE OBJECTIVE LENS APERTURE

1.     Select COND. LENS setting [5].

2.     Insert any one of the movable objective lens apertures while viewing the secondary
       electron image.

3.     If the aperture is so misaligned that you lose the image first turn the CONTRAST
       control fully clockwise, then turn ON the APT. ALIGN. switch and use the
       APERTURE CONTROL X- Y knobs to bring the aperture image to the screen centre.

4.     Set the DYNAMIC FOCUS/APT ALIGN. switch to APT ALIGN. and adjust the
       APERTURE CONTROL X- Y knobs so that the CRT image blurs concentrically.

5.     Return the DYNAMIC FOCUS/APT ALIGN. switch to neutral.

BEAM MONITOR APERTURE

1.     Set the magnification to 250x in HIGH MAG. mode.

2.     Select any of the beam monitor apertures (2 or 3 for normal use).


Issued 9/15/05                                                                       15
HITACHI S-900 OPERATING INSTRUCTIONS                                   Rev1.0

3.     Adjust the beam monitor aperture with the APERTURE CONTROL (X, Y) knobs so
       that the shadow of the aperture doesn't appear on screen.

4.     Set the BEAM MONITOR switch to ON.




Issued 9/15/05                                                             16

				
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