Geometrical Optics 3 Flashcards
(in words) what is an aperture?
An opening defined by a geometrical boundary.
What are the two specific effects of apertures that we are interested in?
- Limiting the field of view of a system
- Controlling the image brightness
(in words) what is the field of view?
how much of a broad object can be seen looking back through an optical system
What is the aperture stop of an optical system?
The physical component that limits the size of the maximum cone of rays that can be handled by the system.
What does the aperture stop control?
The brightness of the system and the marginal rays that can be accepted by the lens
What is the entrance pupil?
The limiting aperture that light rays experience if looking into the optical system from an object point.
It is the image of the controlling aperture stop formed by the imaging elements preceding it.
What is the exit pupil?
The image of the controlling aperture stop formed by the imaging elements following it.
What is the chief ray?
A ray from an object point which passes through the axial point in the plane of the entrance pupil.
It passes through the centre of the aperture stop, the entrance pupil and the exit pupil.
What determines the brightness of the image?
The aperture stop, the entrance window and the exit window
What determines the field of view of an object?
The entrance window, exit window and primarily the field stop.
What is vignetting?
When some of the beam is lost above or below a lens so the brightness of the image varies from the centre and is fuzzy at the edge.
(in words) how is the angular field of view defined?
Twice the angle made by the aperture axis and the chief ray.
How does the field stop control field of view?
By limiting the cone of angles formed by the chief rays
How do you produce a hard edge in the field of view?
Ensure the field stop goes in the image plane
What is the entrance window?
the image of the field stop formed by the imaging elements preceding it
