Omicron NG LEED Product manual

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--~~- I
INSTRUMENTS FOR SURFACE SCIENCE
M3152
~-"""--'--"'D ~ ~
~~)/~~~
._..._.._- ~
including LIAC and MUL
ldsteiner Straf?,e 78, D-65232 Taunusstein, Germany
Tel.: [phone], Fax: [phone]

Preface 2 NG LEED (S) Technical Reference Manual
Copyright
The information in this document is subject to change without notice and does not repre·
sent a commitment on the part of OMICRON Vakuumphysik GmbH. No liability shall be
accepted for any damages resulting from the use ofthis documentation and the related
product.
Please note: . Some components described in this manual may
be optional. The delivery volume depends on the ordered
configuration.
No part of
th is manual may be reproduced or trans tted i any form r by ny eans
electronic or mechanical, including photocopying
an reco ding, for a itho t
the express written permissi
on of OMICRON Vakuu phy ik G bH .
Product names mentioned herein may
be trademark
their respective companies.
Please
note : This documentation is available in English only.
Attention: Please read the safety information on pages 9 and 10
before using the instrument.
Related Manuals
i;~~!
•"
-:: .... ~,;,
SPECTALEED Optics /
•" SPECTALEED Channelplate
,;.::' 'li"
SPA-LEED
•;::-:
AES using SPECTALEED
Table 1 Related manuals.
February 1998 Versi
on 1.2

Preface 3 NG LEED (S) Technical Reference Manual
Contents
List of Figures .. . .. ... ... .. . .. ..... .. .. .... .. ... . .. .. .. ........................ .. ..... ... ... .. .... .. .. ........... 4
List
of Tables................................................ ... ................................................ .. ....... 4
1. Introduction ................................................................................................................. 6
General Description ... ............................................................................ .. ...... .. ........ 6
NORMAL USE..... .............. ... ..... ........ . ........ . ...... .. ............................. ............... ..... ....... 6
Technical Specification.. ... .. ............ .. .. ..... .. .......................................... ... .................. 8
2. Safety Information .......................................................................................................9
3. Installation and Functional Test of Power Supply .................................................. 11
4. Functions and Controls ............................................................................................13
Front Panel .. ... ............................... .. ...................................................................... 13
Back Panel....................................
.. ....................... .. ................... .. ......................... 15
Connectors and
Pin Assignments ......................................... .. ............................. .. 17
Default Settings.......... .. ................... ... ................................................. ... ............. ... 17
5. LIAC Lock-In Amplifier Cassette..............................................................................18
Interface/Precision Oscillator Board .................. ... . .. .................. .. .......... .. ............... 18
Installation. .. ........................................................ .. .. ... ................ .. .......................... 19
Technical Details...... ...... .. ............................................. .. ......... .. .......................... .. 21
6. Matching Unit LEED (MUL)....................................................................................... 22
7. Operation ................................................................................................................... 23
Filament Operation.................. .. ................................... .. ................ ... .................. ... 23
Emission Current Regulation......................................................................... 23
Beam Current Measurement.........................................................................
24
Hints of Operation ......... .... ..................... ... ............................................................. 24
8. Technical Information ............................................................................................... 25
Layout of Unit............................................................... .. . .. .....................................25
Reference Potentials '0' and 'K'..............................................................................
25
Principle of Operation ... ... .. .. ... ....................................... .. ................ .. ... ... ............... 26
9. Adjustments .............................................................................................................. 27
Filament Current Limit............................................................................................ 27
Emission Control Circuit................................. ... ...................... .... .......... ... .............. 27
February 1998 Versi
on 1.2

Preface 4 NG LEED (S) Technical Reference Manual
10. Maintenance ............................................•.............................................................. .. 28
Faultfinding Guide.......... .. .. .. . .. . .. .. ........ .. .. ... .. ........................... .. ... .......... ... ......... ... .28
11. LIAC Operation in Digital Mode ................... ~ ·· i · f · ·· ··+ ··· / ·· +· l ··· + ··· + ·· + ··· / ··· j ··· j ··2 f
12. Circuit Diagrams ......................... .. ....... .. ............ .. ..............................•......•.............. 31
Service Procedure ..............................................................................•....................... .. . 81
Useful OMICRON Addresses .........................................................•..............................83
lndex .......................................................... .. ...... .. ...r ····· ··· ·· · .................................
84
List of Figures
Figure 1: FT 12 connectors: always tighten the fixing screw........................... ...... .. . .... . 2
Figure 2: Front panel layout, schematic diagram. ........................ .. .. ... .. .. ..... ... .... .. ... ..... 3
Figure 3: Back panel layout, schematic diagram......................
.... .. .... ........ .. ... .. .... .. . ... .. 5
Figure 4: The lock-in amplifier module LIA. ..........
.. ................................ .. ....... .......... . ... 0
Figure 5: Location of boards, jumpers and fuses within the unit.. .... .............. .. ........ .. . .. . 5
Figure 6: Principle of operation, schematic diagram...............
.. .. .. ................ .. .......... . ... 6
List of Tables
Table 1: Related manuals......... .. .......................................................................... .. ....... 2
Table 2: Address settings using JP5 and JP6... .. .......... .. .............. .. ............... .......... .. ... 8
Table 3: Time constant logical levels. .......... .. .. .. .............................. .. ............. .... .. .... ..... 9
Table 4: Slope and input logical levels......... .. ...... .. ............ .. ........................ ... ....... .. . . .. . 9
Table 5: Sensitivity logicallevels........ .. ............ .... .... .. .......... .. ...... .. .. ............... .......... . .. . 0
Table 6: Phase settings ofthe lock-
in ... .. ......................... .. .......... .... ................. .. ..... .... . 0
February 1998 Versi
on 1.2

Preface 5 NG LEED (S) Technical Reference Manual
Conditions of CE Compliance
OMICRON instruments are designed for use in an indoor laboratory environment. For
further specification
of environmental requirements and proper use please refer to your
quotation and the product related documentation (i.e. all manuals, see individual packing
list).
The NG LEED SPECTALEED Control Unit complies with CE directives as stated in your
individual delivery documentation if used unaltered and according to the guidelines in the
relevant manuals.
Limits of CE Compliance
This compliance stays valid if repair work is performed according to the guidelines in the
relevant manual and using original OMICRON spare parts and replacements.
This compliance also stays valid if original OMICRON upgrades or extensions are
installed to original OMICRON systems following the attached installation guidelines.
Exceptions
Omicron cannot guarantee compliance with CE directives for components in case of
• changes to the instrument not authorised by OMICRON, e.g.
modifications, add-on's, or the addition of circuit boards or
interfaces to computers supplied by OMICRON.
The customer is responsible forCE compliance of entire experimental setups according
to the relevant CE directives
in case of
• installation of OMICRON components to an on-site system or
device
(e .g. vacuum vessel),
• installation
of OMICRON supplied circuit boards to an on-site
computer,
• alterations and additions to the experimental setup not explicitly
approved by OMICRON
even if performed by an OMICRON service representative.
Spare Parts
Omicron spare parts, accessories and replacements are not CE labelled individually since
they can only
be used in conjunction with other pieces of equipment.
February 1998 Version 1.2

1. Introduction 6 NG LEED (S} Technical Reference Manual
1. Introduction
General Description
The SPECTALEED control unit provides all necessary electrical supplies to operate
various OMICRON rear-view LEED optics
in LEED mode. It supplies the high voltage for
the screen, the suppressor grid voltage and the heating current for the cathode ofthe
integral electron gun. Voltages are generated to drive the electron-optical elements of the
gun at kinetic energies up to 1000
eV.
In addition the control unit can run the SPECTALEE ~ op~c Ei · n Auger ~ l de . lt r~ vide f
1
all
necessary voltages for the internal electron gun (up o 3. ~ ) for a foe ed b a , an
the retard voltage which has to be set by an external pro r~ ming volt e.
An optional electronics package upgrades the SPECTALEED together with the
NG LEED
to a retarding field analyser wi th fully computer controlled data acquisiti on . The electronics
package NG LEED S comprises
NG LEED
• lock-in amplifier integrated into the NG LEED,
• combined interface I precision-oscillator board integrated into the
PC,
matching unit MUL consisting of a preamplifier and a modulator,
• and all necessary control software for lock- in amplifier, retarding
voltage and data acquisition.
The NG LEED
is equipped with an emission current regulation in order to provide a stable
beam current. The beam current can be measured and monitored without biasing the
sample.
NORMAL USE
The NG LEED SPECTALEED Control Unit supplies the SPECTALEED optics with the
filament heati
ng current and the voltages for the lens elements of the electron gun, for the
grid and for the LEED screen.
The NG LEED SPECTALEED Control Unit shall always be used in combination with
either a flange mounted gun SL 1000 I SL 1000 SPA
or a Channelplate optics and NG CPL control unit
or a SPECTALEED optics
or a SPECTALE ED Auger package consisting of
February 1998 Versi
on 1.2

1.1ntroduction 7 NG LEED (S) Technical Reference Manual
l1.SPECTALEED optics
2. NG LEED S: LEED/Auger electronics package
3. PC PEN LEED including OAT 100 data acquisition
software and LIAC control software
or a SPA-LEED package consisting of
li=ipa-leed optics
2. NG LEED: SPECTALE ED control unit
3. NGSPA: SPA-LEED control unit
. ..
4. MUS: matching unit SPA-LEED
5. VOR: preamplifier
6. PC PEN SPA including SPASO SPA-LEED software
Please note: CE compliance for a combination
of certified
products can only
be guaranteed with respect to the lowest level
of certification. Example: when combining a CE-compliant
instrument with a CE 96-compliant set
of electronics, the
combination can only
be guaranteed CE 96 compliance.
The
NG LEED SPECTALEED Control Unit shall always be used
with original cable sets which are explicitly specified for this purpose
• with all cabling connected and secured, if applicable
• with all electronics equipment switched on
in an indoor research laboratory environment
by personnel qualified for operation
of delicate scientific equipment
in accordance with all re lated manuals.
& Warning: Lethal Voltages!!
February 1998
Adjustments and fault finding measureme s
as
~ell a~
installation procedures and repair work
may pnly b
~car
out by authorised personnel qualified to ha
~die I ~thai
oltag
Attention: Please read the safety information
in all relevant
manuals before using the instrument.
ed
~s .
All connectors which were originally supplied with fixing
screws must always be used with their fixing screws
attached and tightly secured.
Version 1.2

1. Introduction 8 NG LEED (S) Technical Reference Manual
Technical Specification
-- ----, ·-
--
-· -
.------
Mains Input 90-264 V,
50/60Hz (150 VA)
Beam Energy I
/Cathode Potential 0 to -3.5 kV, 100
IJA with respect to grour d/earth
Filament Heating 0 to 2.7 A, 0-10 V, floating, centre tapped to cathode potential
Current
Wehnelt 0 to -100 V, 2
mA with respect to cathode potential
Anode +400 V, 2 mA, fixed, with respect to cath pde potential
~---
Lens 1 and Lens 3 -20 V to +2.5 kV, 50 IJA with respect to c thode potential
-
Lens 2 -20 V to +1 .1 kV, 50 IJA with respect to c thode potential
Screen 0 to +7 kV, 500
IJA with respect to earth in steps of 1 kV)
Suppressor 0 V or 80% to 110% of beam energy
IRetard 0 to -2.0 kV, 50
IJA with respect to groun /earth
j Preamp Power ±15 V, 100
mA with respect to ground/earth
±300 V, 50 IJA with respect to ground/ea h
L_
DISPLAY
Gun Parameters 4 1/2 digit panel meter
Current Monitor
__ j
MONITOR OUTPUTS
1Beam Energy
E0 Monitor
Beam Current
1
0 Monitor
0 to +10 V equiv. 0 to -1000 V in LEED mode or ... j
0 to +1 0 V equiv_0 to -3.5 kV in Auger mode
· ---~
1 V per IJA
I
REMOTE CONTROL (switch on/off)
Beam Energy 0 to +10
Vequiv . 0 to -1000 V in L_E_E_D - m . _ od-e-or- ~--+----l
0 to +10 V equiv_0 to -3.5 kV in Auger mode
(+1
0 V reference output is provided)
MECHANICAL
---.- ---- - -
19 inch rackmount width 448.5 mm (84 U), height 132.5 mm (3 U), depth 400 mm
case
~~-~ ~--+------------ ------ ----- - -- --- -- ----- -- -- --
weight 9
kg incl. LIAC
Cables for connecting the screen
HV , grids and electron gun are supplied together with
the SPECTALEED optics. Standard length is 5 m.
February 1998 Versi
on 1.2

2.Safety Information 9 NG LEED (S) Technical Reference Manual
2. Safety Information
Important:
• Please read this manual and the safety information in all related
manuals before installing or using the electronics equipment.
• The safety notes and regulations given in this and related
documentati on have to be observed at all times.
• Check for correct mains voltage before connecting any equipment.
• Do not cover any ventilation slits/holes so as to avoid overheating.
• The NG LEED may only be handled by authorised personnel.
/1.. Warning: Lethal Voltages!!
Adjustments and fault finding measurements may only be carried out by
authorised personnel qualified to handle lethal voltages.
• Lethal voltages may present at the SCREEN and BEAM SHV sockets
and at the GUN 13-pin socket during operati
on .
• Lethal voltages are present inside the NG LEED I NG LEED S.
A Always
• All connectors which were originally supplied with fixing screws
must always be used with their fixing screws attached and tightly
secured.
• Always disconnect the mains supplies of all electrically connected
units before
-opening the vacuum chamber or a control unit case,
-before touching any cable cores or open connectors,
-before touching any part of the in-vacuum components (except
for tip and sample exchange
as described in this manual).
• Leave for a few minutes after switching off for any stored energy to
discharge.
February 1998 Versi
on 1.2

2. Safety Information 10
NG LEED (S) Technical Reference Manual
A This product is only to be ~sed: · j
• indoors, in laboratories meeting the following requirements:
altitude up to 2000 m,
February 1998
temperatures between soc I 41 oF and 40°C 1104 oF (specifications
guaranteed between 20°C I 68°F and 25°C I
7rF)
relative humidity less than 80% for temperatures up to 31 oc I 88°F
(decreasing linearly to 50% relative humidity at 40°C 1104°F)
pollution degree 1 or better (according to IEC 664),
overvoltage category
II or better (according to IEC 664)
mains supply voltage fluctuations not to exceed
±1 0% of the
nominal voltage
Versi on 1.2

3.1nstallation and Functional Test of Power Supply
11 NG LEED (S) Technical Reference Manual
3. Installation and Functional Test of Power Supply
Attention: Installation procedures m<'..y only be carri ed out by
authorised personnel qualified to handle lethal voltages.
Switch off all units and wait for a few minutes (for discharge of
the power supplies) before connecting or disconnecting any
cables.
Make sure all high voltage plugs are secured before switching
any one
of the electronics units on .
Before switching on the SPECTALEED control unit check
on rear panel if:
• mains input voltage is correct (see panel)
• 3-wire power cable
is properly connected
• switch INTERN/EXTERN is set to INTERN
Without connecting the SPECTALE ED optics you may check proper operation ofthe
power supply by pushing the MAINS
ON switch (LEED cable or MUL modulator
connected to power supply). The operation light in the mains switch and the digital panel
meter should now come on . It is possible to check the correct operation of the digital
panel meter and the voltage supplies e.g. by selecting the range position E and turning
the ENERGY potentiometer. The correspondi
ng beam energy is then displayed on the
meter.
If any problems should occur, refer to chapter 10 in this manual.
Before connecting the SPECTALEED optics, make sure that
• ENERGY and FILAMENT potentiometers are turned fully counter
clockwise,
• SCREEN
is set to 0 (zero),
• Mains is switched off.
A IMPORTANT! Switch off all supplies and h ave f
pr at I
~ast
2 minutes for any stored energy to dischari'e
be
ore c
pnnec
the SPECTALEED optics! ing
Now connect your SPECTALEED optics to the control unit using the provided cables.
A
All connectors which were originally sL pplie
~witt
fixir 9
screws must always be used with their
ixing sereNS
attached and tightly secured.
All FT 12 connections have fixing screws which prevent accidental disconnection. The
plugs must always be used with their fixing screw(s) tightened, i.e. plug secured. These
screws, see figure 1, also prevent connecting a plug to the wrong FT
12 feedthrough and
hence should not be removed when disconnecting the plug.
February 1998 Versi
on 1.2

3. Installation and Functional Test of Power Supply 12 NG LEED (S) Technical Reference Manual
Figure 1
Default Setting
FT 12 connectors: always tighten the fixing screw.
After switching
on the power supply, the button LEED is lit and the digital panel meter
shows the beam energy voltage, which should read "0".
February 1998 Versi
on 1.2

4.Functions and Controls 13 NG LEED (S) Technical Reference Manual
4. Functions and Controls
Front Panel
j n 0~-- q - , ~-- -------- . - ,. - ,, --~0.--------------------~ ----- S - PE - C - TA - LE - ED _ C _ O _ NT - ROC -- UN -- IT ~
...- SCREE ,;-' 'S UPPRESSOR '
' .
I • ' I
·-· ~ ·- ·
- ~- !
0- ~ · '
~-'-'
"
' ' .
~-~-~...===:;...
~--===:'~-
s..- .,._ •
' ' u
-..._-.:.==;.J-
.
"
..
=-
~ ?~7~·~~
" f . vu uu ••,.•s« C: • l,.
~==~--~~~;.===~--~ ;,;,~ ~---;;,;;,~~~;-~~
-- LENS 2 LENS 1/ 3 ----.., ' WEHNEL T \ ( EMISSION FILAMENT "\
@ ~ -
. ~ ~ .
'-·---·----'
Figure 2. Front panel layout, schematic diagram.
MA INS
E.AINS ON ___ - _ Push-button to switch on th-;;-~ontrol un i t. The light in t cat :r- ~~ at the I
_ unit is on. Press again to switch unit off.
--+- · ---- - . - -- -I
LEED I Auger
SCREEN
SUPPRESSOR
BEAM ENERGY
FILAMENT
EMISSION
February 1998
.Push-buttons to select LEED or Auger mode.
1LEED mode: all functions are active except for retard voltage.
'Ranges of L 1/3 and L 2 voltages are selected for LEED mode. The
!beam energy is limited to 1 kV.
1Auger mode: Screen and suppressor are not acti ~ e . t an ~ es t
L 1/3 and L 2 voltages are selected for Auger mdl cde . he ea
energy is limited to 3.5 kV. I
Rotary switch to control the high voltage for - th _ e _ ~~~~en - in_7_s--te_p_s _ l.
Range limited to +7 kV. (Only active in LEED mode.)
Potentiometer to control the voltage of the suppressor grid, varies
proportional to the beam energy. Range 80% to 110%
of beam
energy. When fully counter clockwise the switch will click and there
J will be no suppressor potential. (Only active in LEED mod..:.!___
1Ten turn potentiometer to control the beam energy. Range 0 to
1-1000 V in LEED mode and 0 to -3.5 kV in Auger mode. -
Ten turn potentiometer to control the filament heating current.
Range 0 to 2.7 A Green LED is lit when the filament current
is
iimited to the preset value, see also page 27.
Ten-turn potentiometer to control the emission current, range
0 to 50 IJA. Green LED is lit when the emission current is kept
constant by the emission regulator. Ifthe potentiometer
is turned
fully clockwise the emission current is not limited. Note: the
regulation circuit works differently for different filament types. If
changing the filament typ (LaB6 or WTh) please refer to section
Adjustments
on page 27 .
Versi on 1.2

4. Functions and Controls
14 NG LEED (S) Technical Reference Manual
WEHNELT Potentiometer to control the potential of the Wehnelt cylinder of the
electron gun. Range 0 to -100 V with respect to cathode potential.
L 2 OFFSET Potentiometer to control the fixed offset voltage for lens element
L2 .
Range 0 to
+1 00 V. I
L 2 GAIN Potentiometer to control the potential of lens element
L2 . The '
voltage varies proportional to beam energy. Range in LEED mode:
0 to +1 000 V with respect to cathode. Range in Auger mode: 75%
to 85% beam energy.
Lens 1/3 OFFSET Potentiometer to control the fixed offset voltage for lens elements
L1 and L3 . Range -20 V to +100 V.
Lens 1/3 GAIN Ten turn potentiometer to control the potential of lens elements L1 I
and L3 . The voltage varies proportional to the beam energy. Range I
in LEED mode: 0 to +2500 V with respect to cathode. Range in
I
Auger mode: 40% to 65% beam energy.
-·
I
Digital panel meter Potential
of the elements in volts:
and push buttons
L2
Lens L 2 with respect to cathode l
I L 1/3 Lenses L 1 and L 3 with respect to cathode I
I
SUPPR. Suppressor grid with respect to cathode
w Wehnelt cylinder with respect to cathode I
I
I [
I l
fi l Filament heating current
in A
IE
Emission current in mA , measured at the anode I
I
I
L_L
E Beam energy
1n eV
Beam current, range 0.00 to 100
I-lA
________ j
February 1998 Version 1.2

4.Functions and Controls
Back Panel
Serial No . ~ 1
FS1 , FS2: 2. 5AT
i'
MAINS INPUT
90...264V I 50 ... 60Hz
150VA max .
...L
.....
@
CE
15 NG LEED (S) Technical Reference Manual
GUN + GRIDS
REMOTE . ~ TERNAL
SCREEN HV
BEAM HV
NG LEED
SPECT ALE ED CONTROL UNIT
$ 3 'l ~ • . ' 0
BEAM ENERGY
PROGRAM INPUT
O'~o -
000
Oi
\\,\. 0 0 )))
~ - ·
PREAMP POWER
"' ·
(8)
®
.@
Eo
MONITOR
lo
MONITOR
PROGRAM
INPUT
0 1
Figure 3. Back panel layout, schematic diagram.
~
I -· I
~
This unit is supplied with a 3-pin standard Europe'" mains ~
socket for ac input of 90 to 264 volts, 150 VA and 50 o 60 Hz . The
8 wire insulations of the standard 3-lead mains cable ar coloured
in
L accordance with the following code:
Brown: Live
GreenNellow: Earth
Blue: Neutral
Mai ns fuse(s): Smm 0, 20mm long
use 2 x 2.5 A (T) for 90-264 V ac
To change the fuse
• disconnect
ma ins
• lift the flap
us i ng a screw driver for I ~verage
• replace the fuse as indicated above
•
re -fit the fuse holder.
February 1998 Version 1.2

4. Functions and Controls 16 NG LEED (S) Technical Reference Manual
GUN+ GRIDS
[ 0 ~ D
A @ @
2
B @ @
1 2
c @ @
2
D @ @
1 2
E
F
00000
1 2 3 4 5
[ 0
~
]
SCREEN HV
BEAM HV
Remote ~ Internal
113-pin socket, connection to electron gun and ele ~ en ~ of the I
SPECTALE ED optics.
Integral electron gun and grids of the SPECTALE D < ptics ar
connected with a supplied multi-lead cable that fit to re 3-pi1
socket on the rear and the 12-pin feedthrough on he
SPECTALEED Optics.
1A Filament+
2A Filament-
18
Wehnelt
28 Anode
1C Lens 1/3
2C Lens 2
1D Grid 2
2D Grid 3
1F 0 V (Lens
4)
2F Grid 1; Grid 4
3F
Earth/Ground
4F security switch
SF
security switch
BNC-SHV high voltage socket. Screen supply output.
High voltage
is fed to the screen with a single lead cable that fits to
the SHV socket on the control unit and to the HV feedthrough on
SPECTALE ED Optics.
Attention: cover this socket with a protective cap if not in u~
BNC-SHV high voltage socket. Beam energy output (0 to 3.5 kV) . .
Attention: cover this socket with a protective cap if not in use.
Switches program voltage between external input and internal
control of the beam energy.
f-- - ------+- --- ------:::-<--- ---- ----- -- -- ·-··- .
I3-pin DIN socket for external control of energy.
'Input 0 to +10 V for 0 to -1000 V in LEED mode.
·Input 0 to +10 V for 0 to -3500 V in Auger mode.
;Reference output +1 0 V
BumEntrgy
P rogrwninput
February 1998
For connection to the 3-pin DIN socket a mating plug is provided.
External wiring is left to the customer.
1 +10 V Reference Output
2 Earth/Ground
3 Programming Voltage Input
(w i th respect to pin 2)
Version 1.2

4.Functions and Controls
te n- t um pot en tiomete r
Preamp power
17 NG LEED (S) Technical Reference Manu;
'I' The "program beam energy" input can be used to control the beam
energy via a remote control unit. Connect the
+1 OV supply of the
I
input to a 10 turn potentiometer, as shown in the diagram. Use
screened cables to avoid introducing disturbances to the
Iprogramming input
5-pin DIN socket. Supply output for amplifier of matching unit.
1 +300 V electron collector
2 grounded/earthed through matching unit to system
ground/earth.
3 ov
4 -15 v
I
I
I
I
I
I
5 +15 v
~
h~
Eo Monitor
Monitor output of 0 to +10 V proportional to beam 'nergy .
~
_j
lo Monitor
~
Monitor output of 1 V per IJA of beam current
This output can
be used to connect your own voltmeter.
~
Program input for retard voltage in Auger mode. Input of 0 to 10 V
gives an output
of 0 to -2000 Vat GRID 2 and GRID 3 (p i ns 1D and
Program Input
2D of 13-pin socket). Active in Auger mode only.
Connectors and Pin Assignments
A
L3
G2
G1
Locating Sin
atmosph er ic side
Default Settings
12-pin feedthrough, as seen from atmospheric
side.
A Anode
L Lens
G Grid
Fil Filament
W Wehnelt
After switching
on the power supply is in LEED mode, the meter reading shows the beam
energy in volts.
February 1998 Version 1.2
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5. LIAC Lock-In Amplifier Cassette 18 NG LEED (S) Technical Reference Manual
5. LIAC Lock-In Amplifier Cassette
Interface/Precision Oscillator Board
The board contains a precision oscillator for frequencies between 0 and 20 kHz and
amplitudes between 0.1 VPP to 10 Vpp· Three different output signals are available
simultaneously at BNC sockets on the panel:
•
Sine Out gives the sine wave with the preset frequency and
amplitude.
• TTL Sync. yields a TTL signal with the preset frequency.
• 2f OUT gives a TTL signal with double the preset frequency.
The jumpers JP2, JP3 and JP4 select an output attenuation of the sine wave amplitude
by -40 dB, -20 dB and 0 dB, respectively. For small amplitudes it may be sensible to set
an attenuation >0; for normal Auger electron spectroscopy, however, we recommend
selecting 0 dB (JP4).
The parallel 1/0 provides the signal for running the lock-in amplifier.
Four different addresses can be selected for the board using jumpers JPS and JP6, see
table
Table 2.
If you find your board conflicting
addresses. Note that the correct
February 1998
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Version 1.2

5.LIAC Lock-In Amplifier Cassette 19
NG LEED (S) Technical Reference Manual
Installation
Ifthe NG LEED is upgraded with an Auger package (NG LEED S) the back panel will
have an additional lock-in amplifier module (LIA).
Please note:
For full CE compliance the LIAC package must
be installed in factory . The customer is responsible forCE
compliance according to the relevant CE directives in case of
installation of OMICRON supplied circuit boards to an on-site
computer or electronics unit.
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Attention: The lock-in can be set and run manually. For
computer control all dip switches have to
be set to ON. All rotary
switches have to
be set to 0.
Inserting the lock-in amplifier cassette into the
NG LEED power supply (LEED/Auger):
• Make sure the three dip switches S1, S2 and S3 have been set to
ON .
• Make sure the rotary switches for phase control (coarse and fine),
sensitivity and time constant are set to zero.
• Slacken the four screws and remove the blank panel at the rear of
the NG LEED.
• Insert the lock-in amplifier cassette and plug in the power cable of
the lock-in.
• Attach the cassette by tightening the four screws.
To install the interface/oscillator board:
• Remove the cover from your PC .
• Note the board address, see table 2. Preferably write it down as you
need to enter this address when you configure the software.
• Insert the board into a free slot and fix the screws.
• Replace the PC cover.
February 1998 Version 1.2