THEORY OF OPTICS Flashcards
WHAT DOES THE DUALISM OF LIGHT MEAN?
-light is continuous transverse waves of electromagentic field AND a stream of particles
WHAT IS THE SPEED OF LIGHT?
-in a vacuum is 3.108 ms-1. In a medium is always lower
WHAT IS THE FREQUENCY OF LIGHT?
-the number of oscillations per unit time, independent of the environment and gives the color of light. With increasing frequency, increasing the light energy
WHAT IS THE WAVELENGTH OF LIGHT (λ)?
-distance between the corresponding points of the sinusoid. The wavelength of light
is 390nm (violet) to 790nm (red)
WHAT IS THIS RELATIONSHIP?
λ = c / f
wavelength = speed / frequency
WHAT IS THE AMPLITUDE OF LIGHT?
-indicates the maximum deviation from zero sinusoid. The amplitude depends on the intensity of light
MONOCHROMATIC
light waves with one wavelength
POLYCHROMATIC
light waves with more than one wavelength
WHAT IS REFLECTION?
-If the objects surface is smooth and impermeable, all the light is reflected back into space (mirror).
-The angle of incidence of light on the surface equals the angle of reflection.
-If the surface is uneven and impermeable, the rays reflect to space at different angles (the scattered light).
WHAT IS REFRACTION?
-bending of light when it passes from one transparent substance to another.
-caused by changing the speed and wavelength of light
at the interface of 2 objects with different densities
WHAT IS THE DISPERSION OF LIGHT?
-lights of different colours refract at different angles
RAINBOWS = decomposition of white light on
the prism or water droplets
WHAT IS THE INTERFERENCE OF WAVES?
-when two waves meet or superimpose each while traveling along the same medium. This resultant interference of two or more waves causes the medium to take a new shape that results from the net effect of the two individual waves upon the particles of the medium (even multiples of λ/2 = maxima interference)
WHAT IS DIFFRACTION?
-spreading of a wave into regions where it would not be seen if it moved only in straight lines after passing through a narrow split or past an edge
WHAT IS THE DIAMETER OF THE HUMAN EYE?
-24mm
HOW MANY MUSCLES CONTROL EYEBALL MOVEMENTS?
-6 muscles
WHAT ARE THE LAYERS OF THE WALL OF THE EYEBALL?
-Belimo, central choroid (choroidea) and inner retina
WHERE ARE THE GREATEST CONCENTRATION OF CONES LOCATED IN THE RETINA?
-the optic axis (the yellow spot = point of sharpest vision)
WHAT IS THE WHITE OF THE EYE?
-sclera
WHAT IS THE COLOURED PART OF THE EYE?
-the iris
WHAT IS THE OPTICAL POWER OF THE EYE?
-Optical power of the eye is approximately +60 diopters, which accounts for 42 D cornea and 17 - 20 D lens
WHAT IS THE ROLE OF THE CORNEA?
-Separates the internal environment of the eye from ambient air environment (with a refractive index 1
-transparent
-refractive index of the cornea is 1.37 and is the strongest refractive power of 40 diopters
-supplies 70% of eye
-fixed focus power due to this refraction
WHAT DOES ACCOMODATION OF THE EYE MEAN?
- adaption of the eye for near vision
- properly functioning circular muscle in ciliary body, intact suspension apparatus and flexible lens for good accommodation
-15D accommodative width + near point distance of 7cm from eye (10 YEARS)
-10D accommodative width + near point distance of 10cm from eye (20 YEARS)
-4D accommodative width + near point distance of 25cm from eye
WHAT IS PRESBYOPIA?
-decreasing accomodation ability with age (age of 70 - 0D)
WHAT IS EMMETROPIA?
-the ideal state of the eye, which is in equilibrium length of the eye, diffraction media and their optical power, parallel rays are refracted by the eye so that they converge precisely on the retina
-no refractive defects
(opposite of this = AMMETROPIC)