Visible Light Waves in Medicine and Physics
Tishk International University
Faculty of Science
Medical Analyzer Department
Medical Physics
First Grade- 2020-2021
Instructor:
Assist. Prof. Dr. Ronak T. Ali
Assistant: M. Adam
Application of Visible Light
Wave in Medicine
Practical Session (2)
When an electric field changes, so does the magnetic
field. The changing magnetic field causes the electric
field to change. When one field vibrates—so does the
other.
RESULT
-An
electromagnetic wave.
Definition
Visible
light
waves
are
the
only
electromagnetic
waves
we
can
see.
We
see
these
waves as
the
colors
of
the
rainbow.
Each
color
has
a
different
wavelength.
Red
has
the
longest
wavelength
and
violet
has
the
shortest
wavelength.
When
all
the
waves
are
seen
together,
they
make
white
light.
Waves or Particles?
•
Electromagnetic radiation has properties of waves
but also can be thought of as a
stream of
particles.
Example: Light
Light as a wave: Light behaves as a transverse wave which we can filter using
polarized lenses.
Light as particles (photons): When directed at a substance light can knock electrons
off of a substance (Photoelectric effect)
humans
can
see
the
waves
with
λ
=
390-
750
nm
and
f
=
400-
790
THz
(
1
THz
=
10
12
Hz).
visible
light
wave
has
a
wavelenght
(
λ
)
is
400-
720
nm,
while
Frequency
(f)
of
visible
light
wave
is
400-
789
THz.
*1
THz=10
12
Hz
When light enters
a new medium it
bends (refracts).
Each wavelength
bends a different
amount allowing
white light to
separate into it’s
various colors
ROYGBIV.
How
to
happen?
When
white
light
shines
through
a
prism,
the
white
light
is
broken
apart
into
the
colors
of
the
visible
light
spectrum.
Water
vapor
in
the
atmosphere
can
also
break
apart
wavelengths
creating
a
rainbow.
Each
color
in
a
rainbow
corresponds
to
a
different
wavelength
of
electromagnetic
spectrum.
Wavelen
g
th
Color
Wavelength
•
Sir Isaac Newton was
the
first
to test the
visible light
from the sun that
through
on
a prism and produces a
bearn of light that
can
divided into several
colors
such as red,
orange,
yellow,
green, blue, indigo, and
purple.
Figure
Even though man is now very efficient at making artificial
light, the
sun is still the major source of light in the world. The sun is both
beneficial
and
hazardous
to our health.
Light has some interesting properties, many of which are used in
medicine
:
-
1.
The speed of light changes when it goes from material into another.
The ratio of the speed of light in a vacuum to its speed in a given
material is called the
index of refraction
. If a light beam meets a new
material at an angle other than perpendicular, it bends, or is
refracted. This property permits light to be focused and is the reason
we can read and see objects clearly.
2.
Light behaves both as a wave and as a particle. As a wave it
produces
interference
and
diffraction,
which are of minor importance
in medicine. As a particle it can be absorbed by a single molecule.
When a light photon is absorbed its energy is used in various ways. It
can cause a chemical change in the molecule that in turn can cause an
electrical change. This is basically what happens when a light photon is
absorbed in one of the sensitive
cells of the retina
(
the light-sensitive
part of the eye
). The chemical change in a particular point of the
retina triggers an electrical signal to the brain to inform it that a light
photon has been absorbed at that point.
3.
Light is
reflected
to some extent from all surfaces. There are
two
types of reflection.
Diffuse reflection
occurs when rough surfaces
scatter the light in many directions.
Specular reflection
is more useful
type of reflection; it is obtained from very smooth shiny surfaces such
as mirrors where the light is reflected at an angle that is
equal
to
the angle at which it strikes the surface.
Mirrors
are used in many
medical instruments.
Applications of visible light in medicine
1-
An obvious use of visible light in medicine is to permit the
physician to obtain visual information about the patient regarding,
for
example
, the color of his skin and the presence of abnormal structures in
or on his body. this one is done with mirrors.
The curved surface focuses the light at the region of interest. More
sophisticated instruments, such as the
ophthalmoscope
for looking into
the eyes and the
otoscope
for looking into the ears, use basically the
same principle.
2-
A number of instruments, called
endoscopes, are used
for viewing internal body cavities. Special purpose
endoscopes are often given names indicating their purpose
.
For example
,
cystoscopes
are used to examine the bladder,
proctoscopes
are used for examining the rectum, and
bronchoscopes
are used for examining the air passages into
the lungs.
The development of
fiberoptic
techniques permitted the
construction of
flexible
endoscopes.
Flexible
endoscopes
can be used to obtain information from regions of the body
that cannot be examined with
rigid
endoscopes, such as the
small intestine and much of the large intestine.
Flexible
endoscopes usually
have an opening or channel that
permits the physician to take
samples of the tissues (
biopsies
)
for later microscopic examination.
3-
Transillumination
is used clinically in the detection of hydrocephalus
(
water-head
) in infants. Since the skull of young infants is not fully calcified, light
is able to penetrate to the inside of the skull; if there is an excess of relatively clear
cerebrospinal fluid (
CSF
) in the skull,
-
light is scattered to different parts of the skull producing patterns
characteristic of hydrocephalus.
-
The special
transilluminating device
uses a
150W
projection bulb as the
light source.
-
The device has a
two-position
trigger switch. The infant is taken into a dark
room for the study; after a few minutes of
dark adaptation
the physician
pulls the trigger to its
first position
,
which
turns on
a red light that permits
him to find the patient. The physician then points the barrel at the part of the
head to be studied and pulls the trigger to
the
second position
, which
turns off
the red light and turns on the intense white light used for the study.
Infrared
absorbing
glass in the beam removes almost all of the
IR
radiation so that the
light striking the infant is primarily
visible
light.
The physician can then insert a needle
attached to a syringe into the area of
collapse to remove the air between the
lung and chest wall, causing the lung to
reinflate
.
4-
Transillumination
is also used to detect pneumothorax (
collapsed
lung
) in infants. The bright light penetrates the thin front chest wall and
reflects off the back chest wall to indicate the degree of
pneumothorax
.
The
sinuses
, the
gums
, the
breasts
, and the
testes
have also been
studied with
transillumination
.
5-
Visible
light has an important
therapeutic
use. Since
light is a form of energy and is selectively absorbed in
certain molecules, it should not be surprising that it can
cause important physiological effects. Many premature
infants have
jaundice
, a condition in which an excess of
bilirubin
is excreted by the liver into the blood.
Relatively recently (
1958
) it was discovered that most
premature infants recover from jaundice if their bodies
are exposed to visible light (
phototherapy
).
1.
What
is
colour
that
has
the
shortest
wavelenght?
a.
Red
b.
Violet
c.
Green
d.
Yellow
2.
How
long
wavelength
of
violet
colour?
a.
620-750
nm
b.
590-620
nm
c.
380-450
nm
d.
450-475
nm
Sample
Problem~
Link of Video:
https://www.youtube.com/watch?v=bHD8zYImKqA
https://www.youtube.com/watch?v=2Qz5Oof52Cs
https://www.youtube.com/watch?v=tSkAk7pSpbs
Thank
You…
Visible light waves play a crucial role in medicine and physics, where they are the only electromagnetic waves that humans can see. These waves create the colors of the rainbow with varying wavelengths, allowing us to perceive different colors and forms of light. Understanding the properties of visible light waves as electromagnetic radiation helps in applications such as medical analysis, photon behavior, and refraction through different mediums.
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Presentation Transcript
Tishk International University Faculty of Science Medical Analyzer Department Medical Physics Application of Visible Light Wave in Medicine Practical Session (2) First Grade- 2020-2021 Instructor: Assist. Prof. Dr. Ronak T. Ali Assistant: M. Adam
When an electric field changes, so does the magnetic field. The changing magnetic field causes the electric field to change. When one field vibrates so does the other. RESULT-An electromagnetic wave.
Definition Visible light waves are the onlyelectromagnetic waves we can see. We see these waves as the colors of the rainbow. Each color has a different wavelength. Red has the longest wavelength and violet has the shortest wavelength. When all the waves are seen together, they makewhite light.
Waves or Particles? Electromagnetic radiation has properties of waves but also can be thought of as a stream of particles. Example: Light Light as a wave: Light behaves as a transverse wave which we can filter using polarized lenses. Light as particles (photons): When directed at a substance light can knock electrons off of a substance (Photoelectric effect)
humans can see the waves with = 390- 750 nm and f = 400- 790 THz ( 1 THz = 1012Hz). visible light wave has a wavelenght ( ) is 400- 720 nm, while Frequency (f) of visible light wave is 400- 789 THz. *1 THz=1012Hz
When light enters a new medium it bends (refracts). Each wavelength bends a different amount allowing white light to separate into it s various colors ROYGBIV.
How to happen? When white lightshines through a prism, the white light is broken apart into the colors of the visible light spectrum. Water vapor in the atmospherecan also break apart wavelengths creating a rainbow. Each color in a rainbow corresponds to a different wavelength ofelectromagnetic spectrum.
Color Wavelength Color violet blue cyan green yellow orange red Frequency 668 789 THz 631 668 THz 606 630 THz 526 606 THz 508 526 THz 484 508 THz 400 484 THz Wavelength 380 450 nm 450 475 nm 476 495 nm 495 570 nm 570 590 nm 590 620 nm 620 750 nm
Figure Sir Isaac Newton was the first to test the visible light from the sun that through on a prism and produces a bearn of light that can divided into several colors such as red, orange, yellow, green, blue, indigo, and purple.
Even though man is now very efficient at making artificiallight, the sun is still the major source of light in the world. The sun is both beneficial andhazardous to our health. Light has some interesting properties, many of which are used in medicine: - 1. The speed of light changes when it goes from material into another. The ratio of the speed of light in a vacuum to its speed in a given material is called theindex of refraction. If a light beam meets a new material at an angle other than perpendicular, it bends, or is refracted. This property permits light to be focused and is the reason we can read and see objects clearly.
2. Light behaves both as a wave and as a particle. As produces interference and diffraction, which are of minor importance in medicine. As a particle it can be absorbed by a single molecule. When a light photon is absorbed its energy is used in various ways. It can cause a chemical change in the molecule that in turn can cause an electrical change. This is basically what happens when a light photon is absorbed in one of the sensitive cells of the retina (the light-sensitive part of the eye). The chemical change in a particular point of the retina triggers an electrical signal to the brain to inform it that a light photon has been absorbed at that point. a wave it
3. Light is reflected to some extent from all surfaces. There are two types of reflection. Diffuse reflection occurs when rough surfaces scatter the light in many directions. Specular reflection is more useful type of reflection; it is obtained from very smooth shiny surfaces such as mirrors where the light is reflected at the angle at which it strikes the surface. Mirrors are used in many medical instruments. an angle that is equal to
Applications of visible light in medicine 1- An obvious use of visible light in medicine is to permit the physician to obtain visual information about the patient regarding, for example, the color of his skin and the presence of abnormal structures in or on his body. this one is done with mirrors. The curved surface focuses the light at the region of interest. More sophisticated instruments, such as the ophthalmoscope for looking into the eyes and the otoscope for looking into the ears, use basically the same principle.
2- A number of instruments, called endoscopes, are used for viewing internal body cavities. Special purpose endoscopes are often given names indicating their purpose. For example, cystoscopes are used to examine the bladder, proctoscopes are used for examining the rectum, and bronchoscopes are used for examining the air passages into the lungs.
The development of fiberoptic techniques permitted the construction of flexible endoscopes. Flexible endoscopes can be used to obtain information from regions of the body that cannot be examined with rigid endoscopes, such as the small intestine and much of the large intestine. Flexible have an opening or channel that permits the physician to take samples of the tissues (biopsies) for later microscopic examination. endoscopes usually
3- Transillumination is used clinically in the detection of hydrocephalus (water-head) in infants. Since the skull of young infants is not fully calcified, light is able to penetrate to the inside of the skull; if there is an excess of relatively clear cerebrospinal fluid (CSF) in the skull, - light is scattered to different parts of the skull producing patterns characteristic of hydrocephalus. - The special transilluminating device uses a 150W projection bulb as the light source. - The device has a two-position trigger switch. The infant is taken into a dark room for the study; after a few minutes of dark adaptation the physician pulls the trigger to its first position, which turns on a red light that permits him to find the patient. The physician then points the barrel at the part of the head to be studied and pulls the trigger to the second position, which turns off the red light and turns on the intense white light used for the study. Infrared absorbing glass in the beam removes almost all of the IR radiation so that the light striking the infant is primarily visible light.
4- Transillumination is also used to detect pneumothorax (collapsed lung) in infants. The bright light penetrates the thin front chest wall and reflects off the back chest wall pneumothorax. to indicate the degree of The physician can then insert a needle attached to a syringe into the area of collapse to remove the air between the lung and chest wall, causing the lung to reinflate. The sinuses, the gums, the breasts, and the testes have also been studied with transillumination.
5- Visible light has an important therapeutic use. Since light is a form of energy and is selectively absorbed in certain molecules, it should not be surprising that it can cause important physiological effects. Many premature infants have jaundice, a condition in which an excess of bilirubin is excreted by the liver into the blood. Relatively recently (1958) it was discovered that most premature infants recover from jaundice if their bodies are exposed to visible light (phototherapy).
SampleProblem~ 1. What iscolour that has the shortest wavelenght? a. Red b. Violet c. Green d. Yellow 2. How long wavelength of violet colour? a. 620-750nm b. 590-620nm c. 380-450nm d. 450-475nm
Link of Video: https://www.youtube.com/watch?v=bHD8zYImKqA https://www.youtube.com/watch?v=2Qz5Oof52Cs https://www.youtube.com/watch?v=tSkAk7pSpbs
