1. Infrared radiation is emitted from any heated body and has a wavelength longer than visible light, between 760nm and 1mm. 2. Infrared is classified into 3 categories - IR A between 760-1400nm used for therapeutic purposes, IR B between 1400-3000nm also used therapeutically, and IR C between 3000nm-1mm which is non-therapeutic. 3. Infrared lamps can be either luminous (bulb) or non-luminous (coil heater) generators. Luminous lamps emit across the infrared and visible light spectra while non-luminous only emit long infrared wavelengths.

1. Dr. Arjun Patel
MPT- musculoskeletal and sports science
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2. INFRA RED
IR has no color, it is detected by warmth
IR is emitted from any heated body
Its wavelength is higher than visible light
IR has a wavelength of 760nm to 1mm
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3. ELECTRO MAGNETIC
SPECTRUM
INITIAL WAVES WAVELENGTH
R RADIOWAVES 0.1 MM TO 100 KM
I INFRA RED 750 NM TO 0.4 MM
V VISIBLE LIGHT 400 NM TO 750 NM
U ULTRA VIOLET 10 NM TO 400 NM
XG X-RAY / GAMMA
RAYS
0.01 PM TO 100 NM
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4. CLASSIFICATION OF IR
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IR
IR A
760- 1400 NM
THERAPEUTIC
IR B
1400 – 3000
NM
THERAPEUTIC
IR C
3000NM – 1MM
NON THERAPEUTIC

5. Heated material produce IR radiation
Higher temperature are associate with higher frequency, &
shorter wavelength
TEMP α 1 / WAVELENGTH & TEMP α FREQUENCY
If short IR is to be produced material must not be burnt by
higher temperature used.
Convenient method is to heat a resistance WIRE by
passing an electric current through it
Electrical heater is made up of coil of suitable resistance
WIRE , i.e. nickel- chromium alloy, wound on ceramic
insulator
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7. NON LUMINOUS GENERATOR
(coil heater)
IR source is a coil of WIRE wrapped around a
cylindrical ceramic insulator.
In this heaters WIRE glows red, thus giving some
radiation in visible spectrum.
Some IR lamps for therapy have WIRE embedded
in insulation ceramic, ceramic is heated because of
lamp which emits IR so that little or no visible
radiation is emitted
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8. Heater WIRE can also be mounted
behind a metal plate or inside a metal tube
which does not become hot spot but emits
IR in same way
IR emitter is placed at focus of reflector to
produce an uniform wave
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9. If reflector is more spherical instead of
convergence of beam, it will be diverge, this is
usually adapted in clinic.
Reflector & emitter are mounted on a mobile
metal stand which can be adjusted to alter
height & angle of reflector or emitter.
When lamps are switched on they require time
to warm up because of thermal inertia of mass
of metal & insulating material that has to be
heated
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10. Small lamps may take about 5 min. but large
ones may take up to 15 min to reach maximum
emission
Lamps with an exposed coil give off a red glow
although they are collectively designated as “
non-luminous” sources
With non-luminous Exposure is in Long IR
wavelength range
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11. LUMINOUS GENERATOR (Bulb)
They consist of a tungsten filament in a large glass
envelope which contains inert gas at low pressure.
Part of inside of glass bulb is silvered to provide a
reflector
Works on same principle as a simple electric light bulb
Filament is heated to a high temperature around 3000
by a current passed through it
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12. So gives out continuous spectrum in IR & visible region
Oxidation(burnt) does not occur because of no oxygen,
only part of inert air
Radiation extends from SHORT IR to visible light to the
UVR.
UVR is absorbed in glass
Luminous generators are sometimes called RADIANT
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13. POWER
SMALL LAMPS (BOTH) 250-500 WATT
LARGE, NON LUMINOUS 750-1000 W
LARGE , LUMINOUS 750-1500 W
Larger lamps are used to treat extensive
area , but same effect can be achieved by
placing small three lamps in a row
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14. EMISSION
 NON LUMINOUS
3000 – 4000 NM (LONG IR )
 LUMINOUS
SHORT IR
5% VISIBLE
1% UVR
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15. PENETRATION & ABSORBTION
IT DEPENDS UPON:
STRUCTURE
VASCULARITY
PIGMENTATION OF SKIN
WAVELENGTH OF RADIATION
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16. DEPTH OF PENETRATION
Depth of penetration: it is depth at which
approximately 63% of radiation energy has
been absorbed & 37% remains
3000 nm depth of penetration is 0.1mm
Increasing penetration with decreasing
wavelength in short IR to a maximum
penetration depth of 3 mm at 1000 nm
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18. CHOICE OF APPRATUS
 Acute inflammation/recent injury –
sedative effects by non-luminous
generator is more effective than luminous
generator because pain relief is needed
than counter-irritant effect.
 For chronic injury /lesion counter irritant
effect by shorter IR is more effective than
non-luminous generator.
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19. CHOICE OF APPRATUS
 Only on part /surface of body requires
treatment than single lamp will be
sufficient.
 If several part/surface of body requires
treatment than tunnel bath/combination of
4-6lamps is needed.
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20. THERAPEUTIC EFFECT
Relief of pain
Mild heating – sedative effect on superficial
nerve endings
Stronger heating – irritate the superficial
nerve endings – counter irritant effect
( pain may be because of accumulation of
waste product of metabolism and IR
removes that substances so relieves the
pain.) 20

21.  Muscle relaxation – tissue get warm – pain
relief – relieve muscle spasm – perform
exercise more efficiently
 Increased of blood supply – superficial
tissue – treatment of superficial wounds
and infection
 Arthritic condition :small joints of hand and
feet
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22. DANGERS
 Burns
 Electric shock
 Gangrene – area with defective arterial
supply
 Headache – if treatment given during a hot
weather.- back of head.
 faintness – decrease in blood pressure –
brain hypoxia – either patient suddenly
rises from supine position after extensive
treatment 22

23. Technique of application
 Patient
 Position : suitable, well supported, with area to
be treated exposed.
 Explanation : explain nature and effect of
treatment to patient
 Examination and testing : examine the skin to
be treated and test thermal sensation.
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24.  Apparatus :
If a non – luminous lamp is chosen switch it 5
min before treatment starts to allow a time to
warm up
Luminous lamp does not require warm up
time.
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25.  Setting up
 Expose the skin to be treated
 Cover eye, a towel is sufficient
 Position lamp in such a way that rays strike at
90 degree to skin
 Set lamp at 50-75 cm for large lamp (750 to
1000 watts)
 Set lamp at 40-45 cm for small lamp
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26.  Instructions and warning
 Advise patient of required level of heat and it
must not be hot as it burn.
 Ask patient not to touch any part of lamp or to
move during treatment
 Alert therapist if it is more than comfortable
level of heating. 26

27.  Application
 Intensity in most IR lamp is controlled by
distance.
 Doubling the lamp to skin distance reduce the
intensity (wcm-2) to one quarter
 Tripling the lamp to skin distance reduce the
intensity to one ninth
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28.  Termination
At the end of treatment skin should be
checked
On palpation it looks mild or moderately warm
Moderate erythema should be visible.
Erythema tends to vary with skin color, not
just temperature.
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29.  LUMINOUS HEAT
LAMP
Penetrates more
compare to non
luminous
More efficient tissue
heating
Therapeutic effect is
mostly due to heating
 NON LUMINOUS
LAMP
Does not penetrate
more deeply
Mostly absorbed in
skin
Therapeutic effect is
mostly due to sensory
heating
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30. References:
1. Clayton’s Electrotherapy: Theory and Practice
- Forster & Palastanga (Ninth Edition)
2. Electrotherapy Explained – John Low & Ann
Reed (Third Edition)
3. Electrotherapy Simplified – Basanta Kumar
Nanda
4. Basics of Electrotherapy – Subhash Khatri
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