AAiT

Chap1: General Introduction

Optics/Photonics

Masreshaw Demelash, PhD

 BSc in Electrical Eng’g (2005, Mekelle University, Mekelle)
 Double MSc in Optical Engineering (2009, Instiut d’Optique Graduate School, Paris)
 PhD in Modern Biomedical Optical Imaging (2012, Paris Sud 11 University, Paris)

Dr. Masreshaw Demelash

AAiT Definitions
• Optics is a branch of physics that deals with the generation, transmission and
detection of optical wave.

• Optical wave is part of the electromagnetic wave having wavelengths longer

than x-rays and shorter than microwaves.

Optical Wave

Electromagnetic
spectrum

• Optical Engineers uses the principles of optics to design and develop optical
components and optical instruments for various applications
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AAiT Applications of Optics/Photonics
Telecommunication
 Transmitting information from one place to another by sending light pulses through an optical fiber

 Today, virtually all long distance communications is carried over the installed fiber optic network, replacing
copper cables and satellites

EASSy

EASSy - East African Submarine cable System

Dr. Masreshaw Demelash

World map of submarine fiber optics network
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AAiT Applications of Optics/Photonics
Energy
Photovoltaic cells - for generating electricity from light

Today, up to 550 MW is technologically possible from a single photovoltaic power station

President Barack Obama at the DeSoto Next Generation Solar Energy Center, Florida, USA
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AAiT Applications of Optics/Photonics
Consumer Electronics

Displays
CDs, DVDs Players

Laser printer

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AAiT Applications of Optics/Photonics
Consumer Electronics

 Home  Office
Optical scanners
 Energy-saving fluorescent lamps
Fax machines
 Infrared remote controls
Optical fiber telephone cables
 TV flat panel / large screen
Optical data storage
 Optical fibers for cable TV
Laser printers
 Compact disc players
Photocopiers
 IR motion sensors for home security
Overhead slide projectors
 Video disk players
Video teleconferences
 Alarm clock radio with LED display
Laser pointers
 Infrared remote headphones
Laser printer Computer displays
 Infrared remote connections

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AAiT Applications of Optics/Photonics
Astronomy
Telescopes

10.4 m reflective optical telescope 8-inch refracting optical telescope

(Gran Telescopio Canarias (GTC), Spain) (Chabot Space and Science Center, California)
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AAiT Applications of Optics/Photonics
Business Centers (like stores)
 Barcode reader
 Security holograms, etc

Credit card hologram

Barcode reader

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AAiT Applications of Optics/Photonics
Manufacturing
 Laser welding and cutting
 Nondestructive testing
 Precision measurement
 Optical inspection of labeling and packaging
 Image recognition for quality control
 Optical stereo-lithography
 Machine vision
 Laser fabric cutting machines

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AAiT Applications of Optics/Photonics
Transportation

Car
 Infrared security systems
 Optical monitors for antilock brakes
 Optical fiber dashboard displays
 Laser traffic radar
 Solar-powered emergency services

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AAiT Applications of Optics/Photonics
Defense

Thermal camera
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AAiT Applications of Optics/Photonics
Public Security

Fingerprint scanner

CCTV
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AAiT Applications of Optics/Photonics
Biomedical Applications of Optics

1. Diagnostic application – Determining diseases

2. Therapeutic application – Treating diseases

When light and tissue interact, one can affect the other:

 Where tissue affects light

• Used for diagnostic applications (Imaging and monitoring)

 Where light affects tissue

• Used for therapeutic applications (Cutting, coagulating, oxidizing, etc)

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AAiT Applications of Optics/Photonics
1. Diagnostic Application

1.1 Biomedical Optical Imaging

A) Light Microscope

Abebe at EHNRI working on malaria diagnosis

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AAiT Applications of Light Microscopy

250 µm

Human breast (fresh tissue, ex vivo)

Human colon (fresh tissue, ex-vivo) Tumoral colon (Histology)

Crystal violet in
Dr. Masreshaw Demelash Bacteria stained with crystal violet. aqueous solution 15
AAiT Applications of Light Microscopy

Cell Biology

Developmental Biology

Neuroscience Research

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AAiT Applications of Optics/Photonics
1.1 Biomedical Optical Imaging

B) Optical Coherence Tomography (OCT) – Analogues to Ultrasound

Mostly used in Ophthalmology for imaging the various parts of the human eye non-invasively

First commercial OCT system

Dr. Masreshaw Demelash www.meditec.zeiss.de

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AAiT Applications of Optics/Photonics
1.1 Biomedical Optical Imaging

Dr. Masreshaw Demelash http://obel.ee.uwa.edu.au/research/oct/intro 18

AAiT Applications of Optics/Photonics
1.2 Optical Biosensing and Monitoring

Optical biosensing utilizes a rich variety of optical manifestations, in response to

the bioreceptor-analyte interaction

Optical transduction
mechanisms

Frequency Phase Amplitude

change change change

Nonlinear
Fluorescence Raman
processes

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AAiT Applications of Optics/Photonics
1.2 Optical Biosensing and Monitoring

– Clinical monitoring
• The concentration of oxygen ( Pulse Oximeter)
• The blood flow (Laser Doppler Flowmetry, LDF)
• The level of glucose (Glucose meter)

– Drug development
– Environmental monitoring (air, water, and soil)
– Food quality control
– Counter-terrorism (to detect toxins, bacteria, viruses)

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AAiT Applications of Optics/Photonics
1.2 Optical Biosensing and Monitoring
– Clinical monitoring
Ex. Measuring the concentration of oxygen (Pulse Oximeter)

– for safe anaesthesia

– in a neonatal intensive care

– for monitoring of pulmonary disease in adults

– in the investigation of sleep disorders

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AAiT Applications of Optics/Photonics
2 Therapeutic Application
For this purpose, laser light is often used

Photodisruption Ex. Kidney stone destroy

Power density (w/cm2)

Plasma-
induced
ablation
Ex. Refractive error correction
Photoablation

Ex. Eye treatment, Tattoo removal, etc

Thermal
interaction
Ex. Cancer treatment
Photochemical
interaction

Dr. Masreshaw Demelash

Exposure time (s)
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AAiT Applications of Optics/Photonics
2.1 PDT (Photodynamic therapy)
For superficial cancer treatment

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AAiT Applications of Optics/Photonics
2.2 Photocoagulation (thermal effect)
Based on selective photon absorption

Before After Before After

Tattoo removal
Laser treatment of Treatment of port wine stain
diabetic retinopathy using Pulsed dye laser (ms
pulses) tuned to 577 nm

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AAiT Applications of Optics/Photonics
2.3 Refractive error correction (LASIK)

Photodisruption + Photoablation

Laser-Assisted in situ Keratomileusis

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AAiT Applications of Optics/Photonics

Entertainment

DJ lighting

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AAiT Applications of Optics/Photonics
Summary
 Telecommunication (ex, Fiber optics)
 Computers and consumer electronics (ex. Data storage)
 Energy (ex. Photovoltaic cells)
 Manufacturing (ex, Laser micro-machining)
 Defense and public safety (ex. Night vision camera)
 Astronomy (ex. Telescopes)
 Environmental monitoring (ex, Remote sensing)
 Stores (ex. Bar code readers)
 Transportation (ex. Car headlight)
 Entertainment (ex. DJ lighting)
 Biomedicine (ex. Optical microscopes), etc
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AAiT Thank you!

Optics/Photonics
Becoming an enabling technology!

Masreshaw Demelash, PhD

 BSc in Electrical Eng’g (2005, Mekelle University, Mekelle)
 Double MSc in Optical Engineering (2009, Instiut d’Optique Graduate School, Paris)
 PhD in Modern Biomedical Optical Imaging (2012, Paris Sud 11 University, Paris)

Dr. Masreshaw Demelash