Scanning Magnetic Microscope
The Tristan model 770 Scanning
Magnetic Microscope is designed
to measure magnetic fields above
a planar surface with unparalleledspatial resolutions.
Using a liquid nitrogen SQUID
sensor, it can be used to image
diverse objects such as:• shorts on ground planes• traces on a circuit board or

multi-chip module• current distributions• magnetic inks used in currency

Model 770 Scanning SQUID Microscope with dc and ac biasing magnets• The 770 is a fully featured measurement system that allows theuser to extract a magnetic image of the object being measured
over the entire dc – 10 kHz frequency range.
• Whether the samples are circuit boards, multi-chip modules,
steel or aluminum plates, composites or even plastics, the 770
can measure surface and even deeply embedded sources with aspatial resolution down to 50 µm.

Magnetic image of dollar bill section• insulators, ferrous and non-ferrous metals to detect cracks,
voids and corrosion• nanoparticle distributions• flux-motion in HTS materials
Besides measuring magneticfields, the 770 can also be
configured to detect:• induced magnetization• magnetic susceptibility• eddy currents• magnetic hysteresis• Barkhausen effect• micropaleontology• magnetobiologic activity

TRISTANTECHNOLOGIES• The use of a High Temperature Superconducting YBCO stepedge dc SQUID sensor gives it unparalleled sensitivity with theability to measure fields smaller than 20 pT/√Hz. Tristan’s HTS
sensors can also operate in applied magnetic fields exceeding
1000 oersteds.
• The model 770 allows computer controlled scans of objects overa large (15 x 15 cm) area with 25 µm stepping capability withsub-micron stepping available. The user has the ability topreprogram the scan coordinates.
• The 770 requires minimal setup. Automated setup and computer
control makes measurements rapid and repeatable. Systemsoftware provides the ability to control the critical systemcomponents, acquire data from the SQUID sensor, and analyze
the data to determine the magnetic
properties of the sample being
measured. The use of open
architecture software allows the user
to modify and customize nearly all
aspects of operating including image
processing.
scan of concrete showing magnetic impurity

iMAG Electronics
Flux-Locked Loop
Noise
Cancellation
Electronics

Cryogenic
Dewar

Horizontal Field (BX and BY) Sheet Inducer: A horizontal fieldsheet inducer, which can apply an ac magnetic field parallel to thetest surface, to induce a large extended eddy current in a desiredorientation, can be used to image cracks or material loss deep inconductive (e.g., aluminum) structures.
ac Field Compensation Electronics: When imaging conductive
materials, if an ac signal is directly coupled into the system, theresultant signal (from the field coils) may be much larger than thesignal from the sample. To minimize this, Tristan can supply an ac
Compensation system to null the ac signal in the detection coil andextract the induced signal in the object being measured.

SPECIFICATIONSSQUIDsensor

Power Supply

SENSOR: High temperature superconducting quantum interference
device (SQUID) operating at 77 K

MagnetSPATIAL RESOLUTION: Better than 100 µm

SampleSENSITIVITY: 2 x 10-11 tesla/√Hz (20 pT/√Hz)

Non-Magnetic
Stand-off

Function Generator
1234

Lock-in Amplifier

X-Y Scanning Table
Components of the Model 770 system including optional accessories

The Standard model 770 is configured to detect electric currents andto measure remnant magnetic fields. It includes a Single-Channel
Scanning SQUID Magnetometer Probe, iMAG® SQUID Electronics,
Cryogenic dewar, Room Temperature Scanning Stage, Computer
Control and Data Acquisition System, and Imaging Software. The
model 770 can be supplied with additional capabilities to extend its
measurement capabilities.

OPERATING BANDWIDTH: dc - 10 kHz. Measurements can bemade at any frequency. Bandwidths above 20 kHz are available.
CRYOGENIC COOLING: To avoid low frequency noise below 200
Hz, the system uses liquid nitrogen to cool the sensor.
CRYOGENIC HOLD TIME: Time between refills of liquid nitrogen is
typically 3 days
SAMPLE SCANNING RANGE: 15 cm x 15 cm in x-y directions
SCAN STEP SIZE: Adjustable with minimum step size of 25 µm.
SAMPLE PREPARATION: None required. Samples are measured
at room temperature
POWER REQUIREMENTS: 100, 115 or 220 VAC, 50 or 60 Hz

OPTIONS AND ACCESSORIESSCAN AREA: Larger scan areas (e.g., 30 cm x 30 cm) and higher
resolution stepping (25 µm standard) are available upon request.
Substitution OF HTM-1 SQUID Sensor: For measurements wheresensitivities significantly below 20 pT/√Hz are needed and ultimate
spatial resolution is not as important, Tristan can substitute themodel HTM-1 sensor with a significantly larger (1 mm x 1 mm)
detection coil with a sensitivity better than 3 pT/√Hz.
Fixed Field Capability: This option consists of a fixed field thatgenerates a vertical (BZ) field on the sample. This allows magnetic
susceptibility measurements on insulators, conductors and ferrous
materials to be performed.
ac Field Capability: This option allows a small vertical ac magnetic
field to be imposed on the sample. This capability is of interest when
eddy current measurements are desired. This option can be usedsimultaneously with the dc Field Option for added flexibility inmagnetic characterization.

scan of holes in a steel plate

TRISTANTECHNOLOGIES6350 Nancy Ridge Drive, Suite 102
San Diego, CA 92121(858) 550-2700 [fax] 550-2799
http://www. tristantech.com

Represent by
NIKI GLASS CO.,LTD. TOKYOSpecifications subject to change without notice

9-7 Mita 3-Chome Minato-ku Tokyo 108-0073 Japan
TEL : 81-3-3456-4700 FAX : 81-3-3456-3423