tests

Providing Vibration Engineering Services to users of
Electron Microscopes, Steppers, Scanners or other Systems with
Vibration, Electromagnetic Field (EMF, EMI)
Acoustic or Temperature issues.

Spicer SC-12 (EMI - EMF)
Magnetic Field Cancellation System

No need to move that shaky system … Now you can cancel those fields (Electromagnetic Interference, EMI, EMF). Our cancellation system eliminates AC and DC magnetic fields equally well.

AC FIELD CANCELING
FULL 3 AXIS SYSTEM
BANDWIDTH (AC) 0.5 Hz – 5 kHz
50 MILLIGAUSS PK-PK RANGE
AC(RMS) & DC MEASUREMENTS

DC FIELD CANCELING
50 X FIELD IMPROVEMENT (typical)
BANDWIDTH (DC) DC – 5 kHz
1 MICRO GAUSS RESOLUTION
TEST FIELD GENERATOR

See above what EMI - EMF looks like on a SEM image !

The SC12 is a second generation magnetic field canceling system designed as a replacement for the Spicer Consulting SC07. Magnetic field canceling systems are used to improve the performance of electronic instruments which are sensitive to ambient magnetic fields, such as electron microscopes and electron beam metrology tools.

The basic SC12 system comprises a Magnetic Field Control Unit, an AC Magnetic Field Sensor and three (X, Y & Z) multicore cables. The cables are installed in the room where the field is to be cancelled with each cable making one turn around the room as shown. The system works by superimposing a canceling field of the correct amplitude, phase and direction to null out the ambient field. The SC12 Magnetic Field Control Unit contains three power amplifiers which drive currents through the multicore cables to generate the canceling field the SC12 Magnetic Field Sensor measures the field on X, Y, Z orthogonal axes in real time, then the measured signals are amplified and fed back in anti-phase to the power amplifiers. Hence the system is closed loop and the negative feedback nulls the field at the sensor location.

The basic SC12 system is suitable for single microscope applications where the principle sources of unwanted field are the 50/60 Hz power line and rotating machinery (fans etc. It can reduce a 25 milligauss pk-pk 50/60 Hz ambient field to typically 0.5 milligauss. Where the unwanted field includes DC components, caused by elevators, trains, passing motor vehicles etc, a DC sensor can be added to the system. The DC and AC sensors co-operate to provide 50 X reduction of both DC and 50/60 Hz fields. For installations where there are several instruments, each requiring canceling a helmholtz coil option is available enabling the field cables to be placed around each instrument.

The SC12 includes an accurate magnetic field measuring capability with a 3.5 digit panel meter for display. The real time measured fields are also available as analog voltage levels for oscilloscope or chart recorder display: The basic SC12 can measure the true RMS amplitude of AC fields. When a DC sensor is added the system can also measure incremental DC fields. The panel meter can be switched to display any of the axes. To provide rapid "GO/NO GO" monitoring of the field, user definable field "trip levels" have been included. Green LED indicators on the Field Control Unit and the Sensor are lit when the field is "OK". Any field value which exceeds the defined trip level will turn off the "Field OK" LED. The field component which caused the trip is displayed on a multi-segment red LED indicator on the control Unit.

SC12 Specifications

PARAMETER

VALUE / DESCRIPTION

COORDINATE SYSTEM

X, Y, Z rectangular Cartesian

FIELD UNITS

Gauss, Tesla switchable

Basic SC12 system

Components cancelled
Dynamic range
Field reduction ratio
Bandwidth
Detector noise limit

X.Y, Z field components
50 mGauss pk – pk per axis
50 X (typical) at 50/60 Hz
0.5 Hz - 5000 Hz
0.002 mGauss pk-pk

	With added DC sensor
	Ambient DC field Field reduction ration Bandwidth Sensor DC drift

2 Gauss, Max
50 X (typical) at 50/60 Hz 50 X (typical) at DC (incremental)
DC – 5000 Hz
0.1 mGauss/hour, after warm-up

FIELD MEASUREMENT

Types

Real time field
AC - true RMS amplitude
Incremental DC (with DC sensor)

Display

RMS & DC
Sensor dynamic range
Meter ranges

3.5 digit LCD panel meter
40 mGauss pk – pk
X 1 range 0-1.999 mGauss RMS +/- 1.999 mGauss DC
X 10 range 0-19.99 mGauss RMS +/- 19.99 mGauss DC
X 100 range 0-199.9 mGauss RMS+/- 199.9 mGauss DC
( plus equivalent Tesla ranges )

Accuracy

RMS
Incremental DC

+/- 1.0% of reading

+/-0.003 mGauss
+/- 2.5% of reading

Real time field monitor

Signals
Scaling
Range
Source resistance
Connectors
Bandwidth

X, Y, Z, real time field
500 mV / mGauss
+/-10 volts
10K
3 X BNC
AC sensor only 5 Hz - 20 kHz
& DC sensor DC – 20 kHz

Trip range adjustment

AC – RMS
DC

0 – 2.0 mGauss
0 – 5.0 mGauss

POWER

120 V 60 Hz or 240V 50 HZ, 50 VA

60 Hz EMI (15mm WD) Cancellation ON	60 Hz EMI (15mm WD) Cancellation OFF
This type of image disturbance will show as vertical distortion on some SEM/STEM's and horizontal distortion on others.

Passing Train Cancellation ON	Passing Train Cancellation OFF