Basics of Light, Refraction and Optics
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Light is visible electromagnetic radiation that travels in packets called photons. It can come from natural sources like the sun or artificial sources like light bulbs. Refraction is when light changes speed and direction as it passes from one medium to another, like from water to air, causing objects to appear bent. The refractive index measures how much light slows down in a medium and is used to describe materials like glass. Optics is the study of light and its interactions with lenses and other components, which can be used to focus, spread, or diffuse light through different lens shapes like concave, convex, plano, and Fresnel lenses.
Basics of Light, Refraction and Optics
- 1. Light, Refraction, and Optics Kopp Glass, Inc. Research & Engineering Dept. 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 2. What is Light? Light is the visible portion of the spectrum visible to the naked eye. The visible wavelengths are from 380nm to 780nm. White light is composed of multiple colors. Colored light is a more narrow spectrum or white light filtered. Light exists in tiny packets called photons. Photons carry electromagnetic radiation. ER is a form of energy exhibiting wave-like behavior. 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 3. Sources of Light The sun – 40% of its light is visible Fire (or something burning) Incandescent bulb – 10% of its light is visible Light Emitting Diodes Gas Discharge – Neon, Mercury Xenon Chemical Luminescence – glow sticks Bioluminescence – Fireflies and certain types of fish Phosphorescence – energy is absorbed by a substance is released relatively slowly in the form of light 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 4. Speed of Light 1926 Albert Michelson measured the speed of light to be 299,796,000 m/s by using a series of mirrors in the mountaintops of California ~186,282 miles per second. Sunlight takes 8 minutes and 19 seconds to reach the earth. 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 5. Refraction Refraction - is the change in direction of a wave due to a change in its speed. Observed when passing from one medium to another. The straw appears bent due to the refraction of light from water to air. 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 6. Refraction 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc. Is represented by “nD” which is the velocity of light in a vacuum / velocity of light in medium For example, the refractive index of water is 1.33, meaning that light travels 1.33 times as fast in a vacuum as it does in water. Refractive indices are usually measured with a refractometer using a yellow sodium light source with wavelength of 589.3 nm
- 7. Index of Refraction Glass Borosilicate – 1.49 Soda Lime – 1.53 Phosphate – 1.64 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc. Other Materials Air – 1.00 Water – 1.33 Diamond – 2.42 Eye lens 1.36 Fatty Tissue – 1.46 Brain – 1.36
- 8. Refraction Change in refractive index with increasing wavelengths 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 9. Refraction 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 10. Refraction What is it used for? Focusing Light Spreading light Diffusing light Fiber Optics 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 11. Refraction Snells’s Law is a formula used to describe the relationship between the angles of incidence and refraction. Snell's law states that the ratio of the sines of the angles of incidence and refraction is equivalent to the ratio of phase velocities in the two media, or equivalent to the opposite ratio of the indices of refraction. 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 12. Optics Optics is the branch of physics which involves the behavior and properties of light including its interactions with matter. Matter can include liquids, gases, solids, optical components such as lenses and mirrors. 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 13. Optics Types of lenses: Lenses are classified by the curvature of the two optical surfaces. The four basic types are: Concave Convex Plano Fresnel 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 14. Concave Lens At least one lens surface is curved inward. 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 15. Convex Lens At least one surface of the lens is curved out such as a magnifying glass. 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 16. Plano Lens If one of the surfaces is flat it is plano-convex or a plano-concave lens. 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc.
- 17. Fresnel Lens A lens exhibiting the same focus as an aspheric lens. 2013 © Copyright, All Rights Reserved – Kopp Glass, Inc. Easier to manufacture. Less weight. Thinner.