Term
Real objects have what kind of vergence?
Virtual objects? |
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Definition
Real objects: Divergence/ negative vergence
Virtual objects: Convergence/ positive vergence. |
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Term
| If light exits with positive or convergence will it form a real or virtual image? |
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Definition
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Term
| What is an umbra? What is a penumbra? |
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Definition
Umbra = full shadow (shadow is absence of light)
Penumbra = partial shadow |
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Term
| What is the power of a planoconvex thin lens in air with n'=1.56, whose curved surface has a radius of curvature of 6cm? |
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Definition
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Term
Define the secondary Focal point.
Where is it located for + lenses? - lenses? |
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Definition
location of the image point when light from infinity strikes the lens.
+ --> to the right, real image
- --> to the left, virtual image |
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Term
| Define primary focal point. |
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Definition
| the location of the object point from which light can leave as plane waves. @ infinity. |
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Term
| Where is the nodal point on a SSRI? |
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Definition
| Center of curvature --> the point through which light passes undeviated. |
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Term
| What is the lateral mag for an object height of 3cm and an image height of 6cm? |
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Definition
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Term
| You look under water (n=1.50) and see a dinosaur 5 m below. What is its apparent depth? |
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Definition
Apparent depth = d/n = 3.33 m
Things look closer than they actually are in water! |
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Term
When going to a higher n where does the angle of refraction bend?
When going to a lower? |
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Definition
Higher --> bends towards normal
Lower --> away from normal |
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Term
| What property of the cornea does Gonio overcome? What is this principle? |
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Definition
| Total internal reflection - when going to a lower refractive index there will be a critical angle such that angle angle will be totally reflected internally. Any light incident at an angle greater than this critical angle will also be reflected internally. |
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Term
| In our handy dandy step along equation, the sign is positive or negative when going from the corneal to spectacle plane? |
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Definition
Positive: cornea - spec
Negative: spec - cornea |
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Term
| What does the image of the human eye look like? |
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Definition
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Term
| As you increase n, what happens to vergence? Increase or decrease? |
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Definition
| Increasing n increased the change in vergence |
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Term
| In what case does equivalent power become just the sum of the surface powers? |
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Definition
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Term
| What are prescriptions specified using? |
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Definition
| Back vertex power. Also how a lens is red in lensometry |
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Term
| What is the back vertex power? |
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Definition
| vergence of light exiting the optical system given that plane waves entered |
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Term
| In what case do the principle points and nodal points coincide |
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Definition
| If the lens is surrounded on both sides by the same material. n1=n3, f = -f' |
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Term
| What does the aperture stop limit? What is the aperture stop in the eye? |
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Definition
limits Amount of light that can enter the system.
The pupil is the aperture stop in the eye |
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Term
| What does the field stop limit? What do the aperture stop and field stop together limit? |
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Definition
Field stop limits the size of the object that can be images.
The aperture stop and the field stop limit the field of view |
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Term
| What is the entrance pupil? What is the entrance pupil in the eye? |
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Definition
The entrance pupil is the image of the aperture stop formed by all the lenses that lie in front of it.
In the eye: View of the iris through the cornea |
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Term
| If you increase the F#/focal ratio of a camera, will more or less light enter the system |
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Definition
| Decreases. f/ = f/D (D is the diameter of the entrance pupil) |
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Term
| What is the entrance port? |
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Definition
| The image of the field stop formed by lenses in front of it |
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