Download Goals for Chapter 25

Chapter 25 Lecture
Chapter 25:
Optical
Instruments
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Goals for Chapter 25
• To study the camera and the projector.
• To see the eye as an optical instrument.
• To review by doing examples pertaining to
magnifiers, microscopes, and telescopes.
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The Camera – Figure 25.1
• The shutter controls the exposure time and this depends
on the film (which would be chemistry, the darkening of
silver salts on exposure to light).
• The size of the opening provides interesting physics and
is calibrated as "f-stops."
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Using the f-Stop – Figure 25.3
• This problem shows us the physics behind what
photographers refer to as "depth of field."
• Refer to Example 25.1.
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The Digital Camera – Figure 25.4
• The digital camera is an
elegant triumph of
engineering. The
photodiode shown next
to the quarter serves as
the film. The challenge
was to bring a diode
array to a density that
rivaled the clarity of film
photography. New digital
cameras with megapixel
resolution can do this.
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A Better Diode Array Already Found in
Nature?
• The insect eye shown on page 807 rivals or
exceeds any digital camera or projector yet
produced.
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The Eye – Figure 25.5
• The physics of eyeball optics and the chemistry
of rhodopsin's conformational changes to
produce sight is a masterpiece of design and
function.
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Aging Changes the Focal Point of an
Eye – Table 25.1
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Overview of Defects in Vision – Figure 25.6
• More often than not, myopia is a problem for
younger patients. Myopia is difficulty bringing
distant objects into focus.
• Again more often than not, hyperopia is a
problem for older patients. Hyperopia is difficulty
bringing objects close to the eye into focus.
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Astigmatism – Figure 25.7
• Astigmatism is a uniformity of image issue. In
common terms, myopic and hyperoptic vision is
an issue of near and far. Astigmatism is side to
side.
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Hyperoptic Correction – Figure 25.8
• As you get older, you may find that reading the
yellow pages has you holding the book far
enough away from your face that it is difficult to
hold it still. The correction is magnification.
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Myopic Correction – Figure 25.9
• You may remember squinting to see the
blackboard in grade school (changing depth of
field). Glasses, followed by contacts, finally
corrected with LASIK can fix the problem by
using diverging lenses to bring the focus from
the middle of the eye to the retina.
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Quantitative Hyperoptic Correction –
Figure 25.10
• Refer to Example 25.2 on page 810.
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The Magnifier – Figure 25.14
• Taking advantage of a converging lens, position
relative to the object and angular size, visual
perception of an object is magnified.
• Refer to Conceptual Analysis 25.1 and Example
25.5.
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The Microscope – Figure 25.13
• Refer to Conceptual Analysis 25.2 and Example
25.5.
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The Telescope – Figure 25.14
• Taking advantage of a converging lens, position
relative to the object and angular size, visual
perception of an object is magnified just like the
microscope, changing only order of optics.
• Refer to Conceptual Analysis 25.3.
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Reflecting Telescopes – Figure 25.16
• Using mirrors rather than lenses, optical
aberrations may be avoided.
• The Hubble Space Telescope is this type of
instrument.
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