Week 1 Flashcards
Name the sets of images we talk about when we discuss field of view
- Field of uniform illumination
- “Field of view” (at least 1/2 illumination)
- Total field of view
Field of uniform illumination
Set of image points with the same illumination passing through the system
What rays determine the field of uniform illumination?
Chief Ray (points towards the center of the entrance pupil) Marginal Ray( Ray that just passes the edge of the aperture stop)
Field of at least one half illumination
-field of view without specifications refers to this
What rays determine the field of at least one half illumination?
- Chief Ray
2. Ray from the edge of the field stop to the center of the aperture stop
Total field of view
-from zero to full illumination
What rays determine the total field of view?
- Chief Ray
2. Ray that passes from top edge of field stop to bottom edge of aperture stop
Eye relief
The distance from the last surface of an eye piece at which the users eye can obtain the full viewing angle
- the exit pupil of the system matches up with the entrance pupil of your eye would be the minimum
Eye relief trends
- if the eye is outside the distance (too forward or too far back) a reduced field of view will be obtained
- the higher the magnification, the shorter the eye relief
- the larger the intended field of view, the shorter the eye relief
Vignetting
-fall off in illumination for points away from the optical axis
Vignetting trends
- if eye relief is too short and you cannot get your eye close enough, vignetting will occur
- the larger the distance between the edge of full illumination and the bottom of the total field, the larger the vignetting
Can you wear glasses and use binoculars?
-if the lens is not super strong(so the eye relief is longer) glasses can be worn and vignetting will not occur
Field lens
- a plus thin lens that is added to a system to eliminate vignetting
- increases the field of uniform illumination and filed of half illumination
- images the second lens at the same location as the fist lens.
- places at internal real image position
- matches the field views of the lenses
Pupil matching
-maximizes the light getting through the multiple optical system by placing the ENTRANCE PUPIL of SECOND optical system with the EXIT PUPIL of FIRST pupil.
What do virtual reality viewers do?
The lens cuts down the field of view
Keplerian telescope
- plus objective lens and plus ocular lens
- image is magnified and inverted (looking through the ocular side)
Keplarian exit pupil
- ramsden circle or eye ring
- image of the objective lens by the ocular lens
- real image
Markings on binoculars (8X40)
-magnification X diameter of objective lens(mm)
How do you determine the size of the ramsden circle?
Divide diameter of objective lens(mm) by magnification
The larger the objective lens…
The greater the light (brighter)
Galilean telescope
Plus objective lens and MINUS ocular lens
- field of view is limited by OBJECTIVE LENS
- field of view is maximized by GETTING AS CLOSE AS POSSIBLE TO THE OCULAR LENS
- exit pupil is a VIRTUAL image
Can Galilean telescope obtain pupil matching?
NO!
-the exit pupil is inside the telescope so you cannot get the entrance pupil of your eye to it
Stimulus variables of pupil size
- light level
- special configuration
- accommodative state
- pain/noise
Observer variables of pupil size
- individual differences
- age
- day to day changes
- respiration and heart beat
- fright, work load
The pupil is located for the position to
It maximizes the field of view
-cornea has an extremely wide field of view
Environment light
- range is enormous
- on log scale so if surface radiance increases by 10 times, it only appears twice as bright
Retina and light perception
-the retina really does all the work, pupil doesn’t really do that much.
Exposure
Amount of luminous flux (light energy) delivered to a film
