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1/17/24 OPTM 4101 Principles of Optics The Nature of Light - introduction Danuta Sampson, Discipline of...

1/17/24 OPTM 4101 Principles of Optics The Nature of Light - introduction Danuta Sampson, Discipline of Optometry, SAH [email protected] 1 Acknowledgement of country The University of Western Australia acknowledges that its campus is situated on Noongar land, and that Noongar people remain the spiritual and cultural custodians of their land, and continue to practise their values, languages, beliefs and knowledge. Artist: Dr Richard Barry Walley OAM 2 1  1/17/24 Learning Objectives 1. Describe the application of light in life and optometry. 2. Describe the basic nature of light as an electromagnetic wave and a particle. 3. Define the place of visible light in the electromagnetic spectrum. 4. Describe categories of UV light and their role. 5. Name scientists advocating for wave and particle theories of light and describe their contribution. 6. State the behaviours of light that demonstrate its particle nature and those that show its wave behaviour. 3 3 Light: a spectrum of opportunities in our life Telecommunications Manufacturing Renewable energies Lighting Arts Bio-medicine 4 4 2  1/17/24 Light: a spectrum of opportunities in our life 16 MAY The International Day of Light is a global initiative that provides an annual focal point for the continued appreciation of light and the role it plays in science, culture and art, education, and sustainable development, and in fields as diverse as medicine, communications, and energy – towards helping achieve the goals of UNESCO – education, equality, and peace. 5 Light: a spectrum of opportunities in optometry OPTOMETRY Comes from the Greek words + Vision Eye examination Treatment The healthcare profession which provides comprehensive primary eye care. It examines the eye for defects and faults of refraction, prescribes correctional lenses or eye exercises, diagnoses diseases of the eye, and treats such diseases or refers them for treatment. 6 Photo credit (from left): Bruno Henrique, Paul Diaconu, Paul Diaconu @ Pixabay 6 3  1/17/24 But what is light? Electromagnetic (EM) wave Photo credit: EM-Wave.gif, Wikimedia 7 7 Dual nature of light Electromagnetic (EM) wave Light's nature can also be described as a particle travelling through space. We call the particle of light a photon. Photo credit: EM-Wave.gif, Wikimedia 8 8 4  1/17/24 Dual nature of light – a history Around 1700 Light is a particle! Diffraction Isaac Newton 9 Photo credit: Wikipedia Photo credit: Wikipedia Photo credit: Wikipedia 9 Dual nature of light – a history Around 1700 Light is a wave! Christiaan Huygens 10 Photo credit: Wikipedia Photo credit: Wikipedia 10 5  1/17/24 Dual nature of light – a history Light is definitely Around 1800 a wave! The double-slit experiment Thomas Young Photo credit: Wikipedia Output of interference Photo credit: https://photonterrace.net/en/photon/duality/ 11 Dual nature of light – a history Obviously light Around 1850 is a wave! Maxwell’s equations James Clerk Maxwell Photo credit: Wikipedia Photo credit: Power electronic tips: Maxwell’s equations: An intuitive view for engineers 12 6  1/17/24 Dual nature of light – a history Around 1900 Light is a particle! Albert Einstein Photo credit: Wikipedia Photo credit: https://www.electricity-magnetism.org/photoelectric-effect/ 13 13 Dual nature of light Can be explained using Can be explained using Phenomenon waves particles Reflection YES YES Refraction YES YES Interference YES NO Diffraction YES NO Polarisation YES NO Photoelectric effect NO YES 14 14 7  1/17/24 Electromagnetic spectrum Photo credit: Wikipedia 15 15 Electromagnetic spectrum 16 16 8  1/17/24 Electromagnetic spectrum Radio waves Photo credit: https://blog.oureducation.in/propagation-of-radio-waves/ 17 17 Electromagnetic spectrum Microwaves Photo credit: M. Vollmer, Physics of the microwave oven, 2004 18 18 9  1/17/24 Electromagnetic spectrum Infrared waves Photo credit: Wikipedia 19 19 Electromagnetic spectrum Ultraviolet waves Photo credit: https://aktinovolia.com/measurement-ultraviolet-radiations-uva-uvb-uvc/ 20 20 10  1/17/24 Electromagnetic spectrum Ultraviolet waves Photo credit: https://www.montrosedermatology.com/uncategorized/uv-ray-types/ 21 21 Electromagnetic spectrum X-ray waves Print of Wilhelm Röntgen's first A chest X-ray "medical" X-ray of his wife's hand, taken on 22 December 1895 Photos credit: Wikipedia 22 22 11  1/17/24 Electromagnetic spectrum Gamma-ray waves Photo credit: https://earthhow.com/radioactive-decay-isotopes/ 23 23 Electromagnetic spectrum Comparison of wavelength, frequency and energy for the electromagnetic spectrum. (Credit: NASA's Imagine the Universe) 24 24 12  1/17/24 Regions of the electromagnetic spectrum Important for optometrists The approximate wavelength, frequency, and energy limits of the various regions of the electromagnetic spectrum. 25 25 Regions of the electromagnetic spectrum Wavelength (nm) 700 - 1000 Important for optometrists 400 - 700 10 - 400 1 nm = 1 × 10-9 m The approximate wavelength, frequency, and energy limits of the various regions of the electromagnetic spectrum. 26 26 13  1/17/24 Summary Light is everywhere. Light, optics, and photonics impact almost every aspect of our lives, from entertainment to medicine, communications, energy, agriculture, art, and culture. Light is an electromagnetic wave. Light is a particle. There are many different types of electromagnetic waves. They create together electromagnetic spectrum. 27 27 Bibliography and references 1. Hecht, E. (2017). Optics. Pearson. 2. Strong, S. (2023). Introduction to visual optics: a light approach. Elsevier. 3. Schwartz, S.H. (2002). Geometrical and visual optics: A clinical introduction. McGraw-Hill Education. 4. Bennett, A.G. and Rabbett, R.B. (2007). Clinical visual optics. Butterworth- Heinemann. 5. Zubairy, M.S. (2016). A very brief history of light. In: Al-Amri, M., El-Gomati, M., Zubairy, M. (eds) Optics in our time. Springer, Cham. https://doi.org/10.1007/978-3-319-31903-2_1 6. Light: Britannica 28 28 14  1/17/24 Additional materials Youtube videos: a) Light: A spectrum of opportunities https://www.youtube.com/watch?v=XxHYR-A68FA&t=120s b) What is the Electromagnetic Spectrum? https://www.youtube.com/watch?v=m4t7gTmBK3g c) Electromagnetic Spectrum - Basic Introduction https://www.youtube.com/watch?v=FrfcjNTapCU d) Light: Crash Course https://www.youtube.com/watch?v=jjy-eqWM38g 29 29 Thank You 30 15