T.O Prelim-Lesson-1.pdf

ONLINE DELIVERY SYSTEM: CONTENT FRAMEWORK 1. PRELIMINARY REQUIREMENTS Course Title: THEORETICAL OPTICS 6 units 4 Units Lecture/2 Units Laboratory Prerequisites: Physics SY 2020-2021 Semester...

ONLINE DELIVERY SYSTEM: CONTENT FRAMEWORK 1. PRELIMINARY REQUIREMENTS Course Title: THEORETICAL OPTICS 6 units 4 Units Lecture/2 Units Laboratory Prerequisites: Physics SY 2020-2021 Semester First Semester Teacher Dr. Jennifer Lyn G. Viñola Initial Activities This course aims to familiarize the students with the nature, properties, propagation and behavior of light and INTRODUCTION the different phenomena related to light. This deals with the fundamental aspects of physical and geometric TO THE optics. This course is also intended to provide an essential background in photometry and the interaction of light SUBJECT with the probe bodies such as mirrors, lenses and prisms. Upon completion of this course, students will be able to: 1. Acquire sufficient background knowledge in optics to allow them to readily understand optical OBJECTIVES applications introduced elsewhere on the undergraduate course. 2. Exhibit optical problem solving capabilities, which have general applicability. 3. Be competent in undertaking and writing up experiments in Physical sciences. 4. Develop a good working knowledge of the optics of lenses, mirrors, optical instruments and optical aberrations. Theories, Characteristics and definitions of Light Mirrors and Prisms COMPETENCIES Lens Optics Principles of Optical Instruments The class shall be delivered using flexible learning alternative that will utilize various modalities such as online BRIEF ROUND delivery, and classroom face to face sessions. Prepared learning materials shall be made accessible to students in DOWN the MCU LMS Platform or in modules that are either stored in a USB or in a form of handouts. Activities shall be equivalent to four hours lecture and six hours laboratory per week. 1  Lecture Grade: Class Standing (60%)+Major Exam (40%) CS Components: LQ=40%, SQ= 35%, Recitation= 10%, Assignment =10%, Attendance=5% GRADING SYSTEM Laboratory Grade :Class Standing (60%)+Major Exam (40%) CS Components: LQ=25%, SQ= 20%, OS= 40%, Lab. Exercise=10% Attendance=5% Grade= 4(lecture)+2(laboratory) 6 Books: 1. Eckar, Cecil. Geometrical and Visual Optics/Cecil Eckar. Second edition.-[USA] : [s.1], c2018 2. Artal, Pablo ed. Handbook of Visual Optics. Boca Raton, FL : CRC Press, Taylor & Francis Group, c2017 TEXTBOOK / REFERENCES 3. Kaschke, Michael et al. Optical Devices in Ophthalmology And Optometry : Technology, Design Principles And Clinical Applications. Germany : Wiley-VCH, c2014. 4. Schwartz, Steven H. Geometrical And Visual Optics : A Clinical Introduction, 2nd ed. New York : McGraw-Hill, c2013 E- Reference : 1. www.brienholden.org o Scientific Calculator REQUIREMENTS o Pencil o Colored pen/pencil o Bond paper (short) o Ruler 2. LESSONS / TOPICS LESSON NUMBER 1 LESSON TITLE UNIT 1 PROPAGATION AND VELOCITY OF LIGHT 2  1.Definition of Optics and the different behavior of light. 2. Laws governing physical and geometrical optics. 3. Definition of index of refraction a. How to compute for the speed of light in a substance b. How to compute for the index of refraction of a substance 3. History of the Theories of Light a. Corpuscular Theory b. Wave Theory c. Electromagnetic Theory d. Quantum Theory 4. Electromagnetic Spectrum a. Radio waves b. Microwaves c. Infrared radiation c.1 Short Infrared c.2 Long Infrared d. Visible Light e. Ultraviolet e.1 Short Ultraviolet e.2 Long Ultraviolet f. X-ray g. Gamma Rays OBJECTIVES At the end of the lesson the students will be able to: OF THE 1.Define Optics LESSON 2. Differentiate: > Physical Optics > Geometrical Optics 3. Define Index of refraction Compute: - speed of light in a substance - index of refraction of a substance 3  4. Discuss the theories of light 5. Discuss the electromagnetic spectrum LESSON PROPER Lecture: 4 hours (MAIN CONTENT) I. OPTICS Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light. PHASES OF OPTICS 1. Geometrical Optics Phase of optics which treats of the formation of images by light rays and includes the study of the influence of plane and spherical mirrors, plane and spherical refractors, thin and thick lenses, prisms, and optical system upon light. 2. Physical Optics Phase of optics that deals with the physical character and behavior of light and its interaction with matter. II. LIGHT Light is a form of radiant energy that makes object visible makes vision possible. SOURCES OF LIGHT 1. Natural Examples: a. Sun - warms air, water, and land. b. Fire - heat, light, and cooking fuel. c. Lightning d. Firefly 2. Artificial 4 Examples: a. Flashlights b. Light bulb c. Laser beams d. Optical telephone fibers e. Traffic lights PROPERTIES OF LIGHTS 1. Light travels in straight lines at a speed of 186,000miles per second. 2. Light travels VERY FAST – around 300,000 kilometres per second. 3. Light travels much faster than sound Examples: a. Thunder and lightning start at the same time, but we will see the lightning first. b. When a starting pistol is fired we see the smoke first and then hear the bang. 4. We see things because they reflect light into our eyes 5. Shadows are formed when light is blocked by an object BEHAVIOR OF LIGHT Light travels in straight lines at a speed of 186,000miles per second. *Light waves travel faster than sound waves! Light energy from the sun travels through space, reaches earth, and some of it turns to heat energy and warms the earth’s air. When light reaches an object, it is absorbed, reflected, or passes through it. INDEX OF REFRACTION It is the measure of the bending of a ray of light when passing from one medium into another. It is also called as REFRACTIVE INDEX. 5 Table of Different Substance with their Corresponding Index of Refraction SUBSTANCE/MATERIAL Index of Refraction (n) VACUUM 1.0000 AIR 1.000 ICE `1.31 WATER 1.333 ETHYL ALCOHOL 1.36 CROWN GLASS 1.523 LIGHT FLINT GLASS 1.58 DENSE FLINT GLASS 1.666/1.67 ZIRCON 1.923 DIAMOND 2.417 POLYCARBONATE 1.58 CR-39 1.49 PMMA 1.49 6 How to compute for the speed of light in a substance. Formula: Speed of light in a substance = 186,000m/s n Or Speed of light in a substance = 300,000km/s n n = index of refraction of the given substance Sample problem: a. Compute for the Speed of Light in Polycarbonate lens =1.58 Using the formula: Speed of light in a substance = 186,000m/s n Answer: Speed of light in a substance = 186,000m/s 1.58 Speed of light in Polycarbonate Lens = 117,721.52m/s Using the formula: Speed of light in a substance = 300,000km/s n Answer: Speed of light in a substance = 300,000km/s 1.58 Speed of light in Polycarbonate Lens = 189,873.42km/sec b. Compute for the Speed of Light in Dense Flint Glass = 1.666/1.67 7 Using the formula: Speed of light in a substance = 186,000m/s n Answer: Speed of light in a substance = 186,000m/s 1.666 Speed of light in Dense Flint Glass = 111,644.66m/s Using the formula: Speed of light in a substance = 300,000km/s n Answer: Speed of light in a substance = 300,000km/s 1.666 Speed of light in Dense Flint Glass = 180,072.03km/sec How to compute for the index of refraction of a substance. Formula: n = Speed of light in air Speed of light in a substance Examples: a. Compute for the Index of refraction of a substance with a speed of light of 139,534.88m/s and identify the substance n = Speed of light in air Speed of light in a substance Using m/s: Answer: n = 186,000m/s 139,534.88m/s 8 n = 1.333 /substance = water b. Compute for the Index of refraction of a substance with a speed of light of 225,563.91km/s and identify the substance Using km/s: n = 300,000km/s 225,563.91km/s n = 1.333 /substance = water THEORIES OF LIGHT 1. EMISSION/ CORPUSCULAR/PARTICLE THEORY -Created in the seventeenth century by Sir Isaac Newton -States that light emitted by luminous objects consist of tiny particles of matter called corpuscles. When corpuscles hit a surface, each particle is reflected. -Thought that light traveling from air into water will increase the speed, while light entering water will decrease the speed. 9 Reflection Dispersion -Light moves in straight line -Light does not bend into the shadow 10 2. WAVE OR UNDULATORY THEORY Discovered by Christian Huygens, a Dutch scientist, also in the seventeenth century -States that light is emitted in a series of waves that spread out from a light source in all directions. These waves are not affected by gravity. -Furthermore, he disagreed with Newton and said that light traveling from air to water will decrease the speed, and vice versa. Huygens was proved later to be correct. Dispersion Refraction New observations by Thomas Young He performed a decisive experiment that seemed to demand a wave interpretation, turning the title tide of support to the wave theory of light. 11  LIGHT IS A WAVE! It was supported by James Clark Maxwell who suggested that light has its origin in ether waves set up by electrical disturbances. “This velocity is so nearly that of light, that it seems we have strong reason to conclude that light itself (including radiant heat, and other radiations if any) is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field according to electromagnetic laws.” 3. ELECTRO MAGNETIC THEORY (19TH Century) -From then on, light was viewed as a particular region of the electromagnetic spectrum of radiation -Light is an electromagnetic wave! 4. THE QUANTUM THEORY -Stated that light waves travel as separate packets of energy called quanta or photons. -Merged the subjects of the Corpuscular, Wave, and Electromagnetic Theories together. -Later, it was proved that the correct and most accurate theory was the Quantum Theory. Heinrich Hertz performed an experimental support for the wave theory. 12 Augustin Fresnel – published results of his experiments and analysis, which required that light be a transverse wave. He assumed that light waves in an ether were necessarily longitudinal, light rays cannot pass around obstacles. Later Einstein (1905) extended the quantum theory to light, and considered that radiant energy consists of discrete units of energy, called quanta, or photons, the energy of which remains concentrated as they travel through space What is Light really? Light waves are three dimensional. Light waves vibrate in all planes around a center line. The waves have high points called “crests.” Waves also have low points called “troughs.” *The distance from one crest to the next crest is called a “wavelength.” *The number of waves passing a given point in one second is called the “frequency.” 13  wavelength crest troughs TERMINOLOGIES WAVE - is a disturbance that travels in a hypothetical medium called ether. TRANSVERSE WAVE - wave whose particles of the medium vibrate at right angle to the direction in which the wave travels. WAVE MOTION - are transverse waves in which the direction of vibration is at right angles to the direction of propagation. 14 ELECTRO MAGNETIC SPECTRUM The electromagnetic (EM) spectrum is the range of all types of EM radiation. 15 TYPES 1. Radio waves Longest wavelength EM waves Uses: TV broadcasting AM and FM broadcast radio Heart rate monitors Cell phone communication 2. Microwaves Wavelengths from 1 mm- 1 m Uses: Microwave ovens Bluetooth headsets Broadband Wireless Internet Radar GPS 3. Infrared Radiation Wavelengths in between microwaves and visible light Uses: Night vision goggles Remote controls Heat-seeking missiles Short infrared (781 nm to 1,500 nm) If the eye is subjected to high-intensity sources of infra-red radiation can produce thermal lesions which can be manifested in: Cornea- coagulation, leading to opacification Iris - congestion, depigmentation and atrophy due to the absorption of infra-red by the iris pigment Lens - exfoliation of the lens capsule coagulation of protein, and the production of cataract. Retina - necrotic burn. Sources of this type of radiation were direct sunlight into the eye, molten substances such as glass and metal, arc 16 lamps, and infrared lamps. Long infrared (1,500 nm and up) These radiation are absorbed by the cornea and if the eye is exposed to their direct action for long periods of time, mild cases of conjunctivitis will result. Sources of this type of radiation were direct sunlight, molten glass and metal, infrared lamps and arc lamps. 5.Visible light Only type of EM wave able to be detected by the human eye Violet is the highest frequency light Red light is the lowest frequency light Visible (390 nm to 780 nm) Radiation in this region is absorbed in the rods and cones and results in the perception of light. It makes things 17 visible and vision possible. Visible Spectrum: Violet – 390 nm – 445 nm Blue – 446 nm – 499 nm Green – 500 nm – 559 nm Yellow – 560 nm – 591 nm Orange - 592 nm – 649 nm Red – 650 nm – 780 nm Sources are sunlight and artificial illumination 6.Ultraviolet Shorter wavelengths than visible light Uses: Black Lights Sterilizing medical equipment Water disinfection Security images on money 1.Short ultraviolet (14 nm to 310 nm) Exposure to rays in this region for 30 minutes – 24 hours, can cause photochemical damage to the corneal epithelium. This is known as photo-ophthalmia or as photokeratitis or photo-conjunctivitis. Sources of this type of radiation were sunlight at high altitudes; reflections from snow, sand, and water; mercury vapor lamps; electric welding; and ultraviolet lamps. 18 2.Long ultraviolet (310 nm to 389 nm) Exposure for hours to rays of appreciable intensity in this region is usually said to produce no pathological effect. A portion of this region is absorbed by, and produce temporary flourescence in the crystalline lens, without, however, causing any permanent damage. One of the cumulative effects of this radiation is the formation of the lens pigments which cause an increasing yellow coloration of the lens nucleus and lead to a decrease in the light transmission of the lens as one grows older. Sources of this radiation were intense sunlight, arc lamps and ultraviolet lamps. Ultraviolet (cont.) UVA UVB and UVC Energy Highest of waves Lower than UVA Health Risks Extremely low risk for DNA Can cause DNA damage leading damage to skin cancer Can destroy Vitamin A in skin Responsible for sunburn 7.X-rays Tiny wavelength, high energy waves Uses: Medical imaging Airport security Inspecting industrial welds 19  8.Gamma Rays Smallest wavelengths, highest energy EM waves Uses: Food irradiation Cancer treatment Treating wood flooring Citations o Kaschke, Michael et al. Optical Devices in Ophthalmology And Optometry : Technology, Design o Textbook Principles And Clinical Applications. Germany : Wiley-VCH, c2014. o References o Links – electronic o Schwartz, Steven H. Geometrical And Visual Optics : A Clinical Introduction, 2nd ed. New York : McGraw-Hill, c2013 sources 20