Transcript What is total internal reflection?

Experimental and Theoretical Studies of the
Dynamics of the Laser Induced Plasma and
the Associated Particle Generation Process
Marius Maduta
Klein Forest High School
Klein ISD, Houston, Texas
Dr. Sy-Bor Wen/ Assistant Professor and
Vijay M. Sundaram / Ph.D. student
YoungKyong Jo / Ph.D. student
Yu Yang / Ph.D. student
Texas A&M University
Department of Mechanical Engineering
What we have been looking at…
Generation of Core Shell
Quantum Dot Nanoparticles
with Double Pulsed Laser
Subdiffraction Limits
Optical Detection Fabrication
What we have been looking at…
Ultra High-Speed and High Specially Resolved
Temperature Measurements
Inkjet – High Repetition rate nano-inkjet
What my classes are going to do in order to
touch upon some of the concepts applied in
this lab (aspects of the research that are
being bridged into my classroom):
Heat transfer and temperature measurements
were aspects of the lab work
Reflection and Refraction as underpinning
principles of electromagnetic radiation
propagation.
–Total Internal Reflection, as shown in optic fibers.
–Collimation, as an application of refraction.
The pertinent STAAR and TEKS applicable:
The student will demonstrate an understanding of waves
and quantum phenomena.
(P.7) Science concepts.
• characteristics and behavior of waves.
• wave propagation
• wavelength (and what it means in the visible range)
• electromagnetic waves and electromagnetic spectrum
• reflection, refraction
• describe and predict image
• industrial applications
(P.8) Science concepts.
• photoelectric effect
• mass-energy equivalence
• radiation therapy
Heat Transfer using a laser beam Heat Transfer using laser beam will be
performed by the instructor, as a demo,
as an introduction to lasers (special safety
considerations and equipment availability limit the
students’ hands-on involvement at this point).
a. Heat Transfer by lasers using a balloon
b. Heat Transfer by lasers using matchsticks.
Each class will be divided into three groups …
and each group will design one setup and then
present it before the class.
Group 1 – Design a set-up that shows total internal
reflection. This group will have one or two laser pointers
(different colors), one water bottle and water.
Questions to answer: What is reflection? What is total internal
reflection? What are some applications in technology of total internal
reflection?
Each class will be divided into three groups …
and each group will design one setup and then
present it before the class.
Group 2 - Design a set-up that shows total internal
reflection for optical fiber. This group will be given a
laser pointer and a piece of optical fiber.
Questions to answer: What are Fiber Optics? How does an
Optical Fiber transmit light? What are some applications of
Fiber Optic technology?
Each class will be divided into three groups …
and each group will design one setup and then
present it before the class.
Group 3 - Design a set-up that shows light
transmission through optic fibers, and a measurement of
both the initial intensity as well as the intensity of the light
as it is emitted from the optic fiber.
Questions to answer: How do the two intensity
measurements compare? What accounts for the difference in
intensity? Is light “lost” in the optic fiber? What happens when
the optic fiber is bent excessively? What is different between
the red laser and the blue laser?
All Groups 1. Refraction – In groups of three, design two
experiments using any materials available in
the lab in order to show refraction. Explain and
diagram the law of refraction (Snell’s Law).
2. Collimation with two convex lenses. In groups
of three, design and diagram an experimental
set up using the ray box available in the lab, or
two laser pointers, as well as two convex
lenses. Explain the ray geometry involved.
Ray Diagram Example
(what the students should have for the Collimation problem).
Convex Lens
Convex Lens
Ray
Box
Focal length
Outline of daily activities
of the classroom project:
Day 1: A brief introduction of Lasers, definitions and terms.
An introduction to laser safety will be presented (possibly a
pre-test). The students must first pass the laser safety test
(will allow two days for preparation for this test).
Day 2: Engineering Design lesson – a brief overview of
some of the basic concepts and principles. The groups will
be assigned (three to four students per group). Hand out
the assignments.
Day 3: Laser safety test will be administered.
Group 1 – Design a set-up that shows total internal reflection. This
group will have one or two laser pointers (different colors), one
water bottle and water.
Group 2 - Design a set-up that shows total internal reflection for
optical fiber. This group will be given a laser pointer and a piece of
optical fiber.
Group 3 - Design a set-up that shows light transmission through
optic fibers, and a measurement of both the initial intensity as well
as the intensity of the light as it is emitted from the optic fiber.
Outline of daily activities
of the classroom project:
Day 4: Student design time – the students will collaborate
with their teams to find solutions and come up with design
ideas.
Day 5 and Day 6: Design trial and re-design time.
Realistically, we will need two days for this phase. Since
each group will need some set-up time, we will need
approximately 20 minutes for each group to set up and
perform their demonstrations.
Day 7: Final design presentations – 15 minutes per team.
Day 8: Post-test – terms, definitions, problems.
Examples from the lab . . .
Total internal reflection – red laser
following through a stream of water.
Examples from the lab . . .
Total internal reflection –
red laser following through
a stream of water.
Examples from the lab . . .
Can you tell what color this is?
It’s actually red and green
combined. They combine to give
our eyes the impression of yellow!
Examples from the lab . . .
And a blue
laser!
Or is it purple
. . . ???
Examples from the lab . . .
Total internal reflection
through Fluorescein.
How many segments of
light can you see?
Examples from the lab . . .
Focusing the beam inside the Fluorescein.
What color is this laser?
It is actually a blue laser beam that shines through
Fluorescein, where the shorter wavelength is
absorbed and longer wavelengths are emitted.
Heat transfer
1. If the heat transfer is not fast enough, the material in the balloon loses the
accumulated heat to the environment . . .
2. The darker color balloon will absorb the heat fairly quickly, and the balloon
will melt.
3. The black balloon is inside the white balloon. Which one will absorb
the heat faster?
4. Just for kicks . . . Can you guess what’s going on here?
5. So what exactly is happening? Why do the balloons pop?
Pre-Test and Post-Test Challenge
Pre-Test and Post-Test Challenge
Acknowledgements
E3 RET Program Coordinators
Texas A&M
National Science Foundation
Mechanical Engineering Dept
Dr. Sy-Bor Wen and his Lab
Team
… and the 2011 E3 Participants
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