MAGNETOMETER Outline • Pinciples of operation of magnetometer. • How Magnetometer works…??? • Cordinate Systems • Types • SQUID Magnetometer • Applications MAGNETOMETER – PRINCIPLES OF OPERATION Hall Effect Magnetometer Lorentz Force - Benefits-  Solid-state  Low Temperature  Sensitivity  Highly Linear  Small  Cheap Drawbacks-  Saturation limit  Calibration Issues How Magnetometers Work..??? Coordinate Systems TYPES OF MAGNETOMETER SQUID MAGNETOMETER APPLICATIONS OF MAGNETOMETER 1. They are used for navigational purposes. 2. They are used in anti-lock braking systems in vehicles. 3. Fluxgate magnetometers have been used in space missions for magnetic field measurements. 4. Magnetometers are used for mineral exploration; it is used to search world-class deposits of gold,silver, iron copper, etc. 5. They are used in many defence applications; UAVs, submarines, etc. 6. Magnetometers have found usages in smartphones which have applications that serve as compasses. 7. And many more.. THANK YOU.

1. GOVERNMENT
ENGINEERING COLLEGE,
GANDHINAGAR
Submitted by:-
Tanish Gupta{150130117029}

2. MEASUREMENTS
AND
INSTRUMENTATION

3. TOPIC :-
MAGNETOMETER

4. MAGNETOMETER– WHAT IS IT?
Magnetometers are devices that measure
magnetic fields. A magnetometer is an
instrument with a sensor that measures
magnetic flux density B (in units of Tesla or
As/ m2). Magnetometers refer to sensors used
for sensing magnetic fields OR to systems
which measure magnetic field using one or
more sensors.

5.  Since , magnetic flux density in air is directly
proportional to magnetic field strength, a
magnetometer is capable of detecting
fluctuations in the Earth's field.
 Materials that distort magnetic flux lines are
known as magnetic, and include materials
such as magnetite that possess magnetic fields
of their own, as well as very high magnetic
conductivity. Such materials create distortions
in the Earth's magnetic flux that is flowing
around them.

6. Outline
• Pinciples of operation of magnetometer.
• How Magnetometer works…???
• Cordinate Systems
• Types
• SQUID Magnetometer
• Applications

7. MAGNETOMETER –
PRINCIPLES OF OPERATION
Hall Effect Magnetometer
Lorentz Force -
Benefits-
 Solid-state
 Low Temperature
 Sensitivity
 Highly Linear
 Small
 Cheap
Drawbacks-
 Saturation limit
 Calibration Issues

8. How Magnetometers Work..???
• Magnetometer measures the magnetic field it is
applied to. The magnetometer outputs three
magnitudes: X, Y and Z.
• From these three values you can construct the
magnetic field vector (magnitude and direction)
B= [X, Y, Z]

9. Coordinate Systems
• Because magnetic fields have a direction, in order to
communicate about magnetic fields, we need to define a
coordinate system.
• Three main coordinate systems are used for magnetometer
data:
–Geographic (XYZ)
–Geomagnetic (XYZ or HDZ - BEWARE!!)
–Compass-type (HDZ)

11. TYPES OF
MAGNETOMETER
• Magnetometers are classified into two categories:
• Vector magnetometers that measure the flux density value
in a specific direction in 3 dimensional space. An example
is a fluxgate magnetometer that can measure the strength of
any component of the Earth’s field by orienting the sensor
in the direction of the desired component.
• Scalar magnetometers that measure only the magnitude of
the vector passing through the sensor regardless of the
direction. Quantum magnetometers are an example of this
type of magnetometer.

12. 1. Vector magnetometers
• Low-Field Vector Magnetometers
• The Induction Coil Magnetometer
• The Fluxgate Magnetomete
• The SQUID Magnetometer

13. The Induction Coil Magnetometer
• The induction or search coil, which is one of the simplest
magnetic field sensing devices, is based on Faraday’s law.
• This law states that if a loop of wire is subjected to a
changing magnetic flux, f, through the area enclosed by the
loop, then a voltage will be induced in the loop that is
proportional to the rate of change of the flux:
e (t )= - dɸ / dt

14. Induction or search coil sensors consist of a loop of wire (or a
solenoid), which may or may not surround a ferromagnetic core.
(a) Air core loop antenna; (b) solenoid induction coil antenna with
ferromagnetic core

15. The Fluxgate Magnetometer
• The fluxgate
magnetometer has been
and is the workhorse of
magnetic field strength
instruments both on Earth
and in space. It is rugged,
reliable, physically small,
and requires very little
power to operate.
• The heart of the
magnetometer is the
fluxgate. It is the
transducer that converts a
magnetic field into an
electric voltage

16. (a) Ring core.
(b) Fluxgate
sensors

17. 2. Scalar Magnetometers
• Total field magnetometers or scalar
magnetometers measure the magnitude of
the vector magnetic field
• measures the total strength of the magnetic
field they are subjected to.

18. Scalar Magnetometers
The two most widely used scalar
magnetometers are the
1.proton precession
2.optically pumped magnetometer

19. Proton precession Magnetometer
• Proton precession
magnetometers, also known as
proton magnetometers, PPMs
or simply mags, measure the
resonance frequency of protons
(hydrogen nuclei) in the
magnetic field to be measured,
due to nuclear magnetic
resonance (NMR).
measurement range: typically
20 mT to 100 mT.

20. OPTICALLY PUMPED MAGNETOMETERS
• Optically pumped
magnetometers include 1
nuclear magnetometer
(Helium 3) and four
electron resonance
magnetometers (Helium 4,
Rubidium, Cesium and
Potassium).
• Alkali vapor optically
pumped magnetometers
use gaseous alkali metals
from the first column of
the periodic table, such as
Cesium, Potassium or
Rubidium

22. SQUID MAGNETOMETER
Superconducting quantum interference devices, measure extremely
small changes in magnetic fields. They are very sensitive vector
magnetometers, with noise levels as low as 3 fT Hz−½ in
commercial instruments and 0.4 fT Hz−½ in experimental devices.
Many liquid-helium-cooled commercial SQUIDs achieve a flat noise
spectrum from near DC (less than 1 Hz) to tens of kilohertz,
making such devices ideal for time-domain biomagnetic signal
measurements. SERF atomic magnetometers demonstrated in
laboratories so far reach competitive noise floor but in relatively
small frequency ranges.

24. SQUID magnetometers require cooling with liquid helium
(4.2 K) or liquid nitrogen (77 K) to operate, hence the
packaging requirements to use them are rather stringent
both from a thermal-mechanical as well as magnetic
standpoint. SQUID magnetometers are most commonly
used to measure the magnetic fields produced by
laboratory samples, also for brain or heart activity
(magnetoencephalography and magnetocardiography,
respectively). Geophysical surveys use SQUIDs from time
to time, but the logistics of cooling the SQUID are much
more complicated than other magnetometers that
operate at room temperature.

25. APPLICATIONS OF MAGNETOMETER
1. They are used for navigational purposes.
2. They are used in anti-lock braking systems in vehicles.
3. Fluxgate magnetometers have been used in space missions for
magnetic field measurements.
4. Magnetometers are used for mineral exploration; it is used to
search world-class deposits of gold,silver, iron copper, etc.
5. They are used in many defence applications; UAVs, submarines, etc.
6. Magnetometers have found usages in smartphones which have
applications that serve as compasses.
7. And many more..