Astigmatism
An optical system that demonstrates astigmatism is one whose point spread function is (antisymmetric/asymmetric/circuilar). This means that the system's linespread function will depend on the (line orientation/line length/input size).
An optical system that demonstrates astigmatism is one whose point spread function is asymmetric . This means that the system's linespread function will depend on the line orientation.
Rods and Cones
Cones and rods are photoreceptors. Cones are mainly responsive in the (night/day/dawn), meaning they have (low/high/medium) sensitivity to absolute light levels. They are concentrated in the (retina/lense/fovea) , and there are estimated to be about __ million cones.
Rods are not found in the fovea [one word]. They express the photopigment ____ and are mainly sensitive to (short/medium/long) wavelength light. There are estimated about million rods __.
Cones and rods are photoreceptors. Cones are mainly responsive in the day , meaning they have low sensitivity to absolute light levels. They are concentrated in the fovea , and there are estimated to be about 5 million cones.
Rods are not found in the fovea [one word]. They express the photopigment rhodopsin and are mainly sensitive to short wavelength light. There are estimated to be about 100 million rods.
Retinal cell types 1
Cells that send signals from the retina to the rest of the brain are called
Blind spot
The "blind spot" is a region of the retina containing (only rods/only cones/no photoreceptors) . It lies on the (temporal/nasal/central) side of the retina. To find the blind spot in your right eye, focus on a point in front of you, close your left eye, then move your finger (leftwards/rightwards) from the focal point.
The "blind spot" is a region of the retina containing no photoreceptors . It lies on the nasal side of the retina. To find the blind spot in your right eye, focus on a point in front of you, close your left eye, then move your finger rightwards from the focal point.
Optical path through the eye
Before reaching the photoreceptors, light passes through the (aqueous humor/cornea/lens/retina/vitreous humor/cornea) ,
then the (aqueous humor/cornea/lens/retina/vitreous humor/cornea),
then the (aqueous humor/cornea/lens/retina/vitreous humor/cornea) ,
followed by the (aqueous humor/cornea/lens/retina/vitreous humor/cornea) ,
then the (aqueous humor/cornea/lens/retina/vitreous humor/cornea).
Before reaching the photoreceptors, light passes through the cornea ,
then the aqueous humor ,
then the pupil ,
then the lens ,
followed by the vitreous humor ,
then the retina.
Relationship between pointspread and linespread
The pointspread and linespread functions describe the spread (blurring) induced by an optical system on a point and a line respectively. Which statements are true (multiple answers possible):
Nearest focal point
To bring near objects into focus, the ciliary muscles (contract/relax/strengthen), making the lens of the eye (less thick/more round/more thick) , in a process known as ____ . This capacity decreases with age such that by (40-50/50-60/60-70)
years, accommodation amplitude is less than 2.5 diopters (compared to around __ diopters for 20-year-olds).
To bring near objects into focus, the ciliary muscles contract , making the lens of the eye more thick , in a process known as accommodation . This capacity decreases with age such that by 50-60 years, accommodation amplitude is less than 2.5 diopters (compared to around 10 diopters for 20-year-olds).
Measuring optical quality
In 1966, Campbell and Gubisch estimated the (pointspread/linespread) of the human eye using the ___ method. They found that for (large/medium/small)
pupil sizes, the retinal image quality was mainly limited by ____.
In 1966, Campbell and Gubisch estimated the linespread of the human eye using the double pass method. They found that for small pupil sizes, the retinal image quality was mainly limited by diffraction .
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