Pupils and Stops And Related Effects Flashcards
(42 cards)
Field of view
- the extent of the object plane that is imaged by the system
- conventional field of view
What happens to the field of view as you move closer?
It becomes larger
How is the field of view measured
- linear size in the object plane or image plane
- measured as an angle
- commonly measured as the angle of half of illumination
Angle of half illumination
Half of the light available gets to the field of view
How does a minus lens affect field of view?
- smaller objects
- bigger field of view
How does a plug lens affect the field of view?
- larger objects
- smaller field of view
Trends in field of view
- a minus lens will increase the field of view by minifying the image
- A plus lens will decrease the field of view by magnifying the image
Image space field of view
- the limits to the linear field of view a expressed in image space
- a 16’ giraffe looks like it’s 3 inches
What is the field of view is determined by two apertures of the optical systems
- aperture stop
- field stop
Aperature
- opening through which light travels
- structure associated with that opening
- diameter of the opening
Stop
-the physical entity that restricts the light
Object space
Where the light rays are coming from
Not always on the left
Image space
Where the image is
Not always on the right
Aperture stop
- the physical entity that is most effective at limiting the amount of light that passes through the system
- system reversible
- same structure regardless of the direction of light (when collimated)
- could vary with the distance of object
- if the object is a near object and light is not parallel, the aperture is determined by the smallest angle
Entrance pupil
- image of the aperture by any lenses in front of it
- image of the aperture stop as seen from the object side
Entrance pupil of the eye
- virtual image of the iris that is magnified and appears further from the cornea
- if it’s further from cornea…it’ll be magnified
Exit pupil
- image of the aperture stop as seen from the image side
- the exit pupil is the image of the aperture stop formed by any lenses behind it-exit pupil of the eye is a virtual image of the iris that is magnified and appears further from the retina
Field stop
The physical entity that is most effective at limiting the field of view together with the aperture stop
How do you find the field stop?
You find the aperture stop and then start in the middle of that and find the smallest angle
-for the natural pupil, the field stop is the outside aperture that limits the field of view
Entrance port
- image of the field stop as seen front he object side
- the entrance port is the image of the field stop by any lenses in front of it
Exit port
- image of the field stop as seen from the image side
- it is the image of the field stop formed by any lenses behind it
Marginal ray
The ray that just passes the edge of the aperture stop
2
Chief ray
The ray from an object point that is incident on the system pointing towards the center of the entrance pupil
What does chief ray determine
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