Transcript Chapter 25 Optical Instruments

Chapter 25 Optical Instruments
•25-1 The Camera
•The basic parts of a camera are the light-tight
box, lens, and shutter.
•Shutter speed refers to the speed of the shutter
opening and closing.
•F-stop controls the amount of light coming into
the light-tight box, by controlling the size of the
opening
•F-stop=f/D
25-1 The Camera
• Circles of confusion involve objects not in focus
forming circles of non-focused images…not all
distances of objects can be in focus at one time.
• A smaller lens opening will cause there to be a wider
range of in-focus object distances.
• See normal lens, telephoto lens, wide-angle lens,
zoom lens.
• In a single-lens reflex system, you view through the
actual lens… some cameras have a separate window.
• See Example 25-1
25-2 The Human Eye…Corrective
Lenses
• See the eye pg. 761
• Focusing of the eye involves accomodation…
muscles contract to make the lens thicker for
nearby objects and relax to make the lens thinner
for far objects.
• The closest an eye can focus is the near point.
• The farthest an eye can focus is the far point.
• The normal eye has a npt of 25 cm and a fpt of
infinity.
• See nearsightedness, farsightedness, and
astigmatism on page 763
• See Examples25-3 and 25-4 on p 764.
25-3 The Magnifying Glass
• Simple magnifier or magnifying glass.
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M=q’ /q
M=q’ /q=(h/f)/(h/N) = N/f
1/do = 1/f-(1/di )= 1/f + 1/N
See page 767 for formulas and Example 25-6
25-4 Telescopes
• Several types of astronomical telescopes
exist…
• Keplarian (refractive)
• Objective lens …closest
to object…eyepiece
25-4 Telescopes
…closest to eye.
• M=q’ /q= fo /fe
• See Example 25-6
• Reflecting telescopes use a large mirror
instead of an objective lens.
25-4 Telescopes
• Terrestrial telescopes provide upright images.
• Galilean and spyglass types. p770
25-5 Compound Microscopes
• See formulas page 771
• See Example 25-7 p772
25-6 Aberrations of Lenses and Mirrors
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Spherical aberration
Circle of least confusion.
Coma and off-axis astigmatism
Curvature of field
Distortion- caused by variation of magnification
at different distances.
• See p 773
• Chromatic aberration
• Achromatic doublet
25-7 Limits of Resolution
• Resolution is the ability to discern between
two separate points.
• q= (1.22l)/D where D is diameter
• See Example 25-8 p 776
HOMEWORK
• P788 PR#1-3, 10,19-21, 28-30,38-39,44, 46-47
• Due Wednesday BOP
• Test Chapter 24/25 on Thursday…(No Not
Monday.)
• Final Packets due April 29th