Lecture 4 Flashcards
Light
A narrow band of electromagnetic radiation that can be conceptualized as a wave or a stream of photons
-A waveform when it travels in space
Photon
A quantum of visible light (or other form of electromagnetic radiation) demonstrating both particle and wave properties
-As it hits the retina and is transduced in neuronal activity
Light Scattering
The redirection of light as it interacts with particles or molecules in a medium, causing the light to deviate from its original path.
-This phenomenon depends on the size, shape, and composition of the particles relative to the wavelength of the light
Rayleigh Scattering
The scattering of light by particles much smaller than the wavelength of light, typically occuring in gases.
-It causes shorter wavelengths (e.g. blue) to scatter more than longer wavelengths, explaining phenomena like the blue colour of the sky
Mie Scattering
The scattering of light by particles that are comparable in size to the wavelength of light, such as water droplets or dust.
-Unlike Rayleigh scattering, it affects all wavelengths more equally and often results in a white or grayish appearance, such as in clouds or haze
Non-Selective Scattering
The scattering of light by particles much larger than the wavelength of light, such as large water droplets in fog.
-This type of scattering affects all wavelengths equally, resulting in a uniform, white appearance.
Light Absorption
The process by which light energy is taken up by a material, converting it into other forms of energy, such as heat, rather than being transmitted or reflected
Light Reflection
The process by which light bounces of the surface of a material.
-Reflection can be : -Specular Reflection
-Diffus Reflection
Specular Reflection
Where light reflects off a smooth surface in a single, predictable direction
Diffus Reflection
Where light reflects off a rough surface, scattering in many directions
Transmission
The passage of light through a material, where the light continues to propagate without being absorbed or reflected
-E.g. passes straight through glass
Refraction
The bending of light as it passes from one medium to another with a different refractive index, changing its speed and direction
-E.g. changes angle from glass to water
Polarizing Glasses
Only let light pass with a certain polarity can be used to reduce the total amount of light that reaches the retina
Cornea
The transparent, dome-shaped outer layer at the front of the eye that helps focus light onto the retina
Anterior Chamber
The fluid-filled space between the cornea and the iris, containing aqueous humor
Aqueous Humor
Nourishes the cornea and lens
Pupil
The circular opening in the center of the iris that regulates the amount of light entering the eye
-It acts as a diaphragm and is attached to the ciliary muscle via zonular fibers
Vitreous Humor
The clear, gel-likesubstance that fills the space between the lens and the retina, helping maintain the eye’s shape and transmitting light to the retina
Choroid
The vasular layer between the retina and sclera that provides oxygen and nutrients to the outer layers of the retina
Sclera
The tough, white, outer layer of the eye that provides structural support and protection
Retina
The thin, light-sensitive tissue lining the back of the eye, where photoreceptor cells (rods + cones) convert light into neural signals for visual processing
Optical Infinity
Objects that are at a distance of 20 feet (6 meters) or more from the eye are said to be here and do not require accommodation to be seen distinctly be a healthy eye
Emmetropia
When light rays that are coming from objects located at optical infinity are naturally focused on the retina without any anomolies, the eye is in this condition.
-Lens in relaxed
Accommodation
The process by which the eye’s lens changes shape, controlled by the ciliary muscles, to focus light on the retina for clear visio at different distances
Focal Length (f’)
The distance between the optical center of a lens and its focal point (F’), where parallel rays of light converge or appear to diverge
-It determines the len’s magnifying power and ability to focus on objects at a various distances
Presbyopia
An age-related condition where the eye gradually loses the ability to focus on nearby objects .
-It is caused by a reduction in the elasticity of the lens and a weakening of the ciliary muscles, which together limit the eye’s ability to adjust (accommodate) for near vision
-This typically becomes noticeable around the age of 40
-Stiffening of lens
-Can’t see from close / close objects
Hyperopia (Farsightedness)
A refractive error where distant objects appear clearer than near ones because light focuses behind the retina, often due to a shorter eyeball
-Can’t see from close
Myopia (Nearsightedness)
A refractive error where near objects appear clearer than distant ones because light focuses in front of the retina, often due to a longer eyeball
-Can’t se from far
Astigmatism
A refractive error caused by an irregularly shaped cornea or lens, leading to distorted or blurred vision at all distances because light is focused unevenly on the retina
-Feels like different pictures of the world are superposed
