5.1OpticalInstruments

# 5.1OpticalInstruments - 5.1 Optical Instruments...

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1 5.1 Optical Instruments - Polarization • Optical Instruments – Simple magnifier – Compound microscope – Telescope • Wave optics –Polarization Magnifiers We magnify the image a small object by bringing it close to our eye. • But we cannot bring it closer than the near point. • A magnifier can produce a larger image of the object at the near point (or farther away) that can be focused on by the eye. • The larger image is due to Angular Magnification Angular size 25 cm θ Objects closer than the near point are not in focus. P unfocused image on retina Not to scale The angle θ increases as p decreases The image size increases Simple Magnifier 25 cm h A converging lens in combination with the lens of the eye forms an image on the retina from an object closer than the near point of the eye. Ignore the distance between the lens and the eye Larger Real image Virtual image formed by magnifier Angular Magnification The angular magnification is the ratio of θ for the magnified image compared to value of θ o for the object at the near point of the eye. (25 cm) 25 cm f object virtual image θ h’ h o m θ = θ Magnified 25 cm θ o h Unmagnified Angular magnification The angular magnification for the simple magnifier can have a range of values because the focal length of the eye can vary due to accommodation. The simplest case is the magnification for the relaxed eye. (focused at infinity)

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2 Simple Magnifier 25 cm f object θ p h h f θ≈ 25 cm θ o h Unmagnified Angular magnification o h 25cm Angular magnification 0 25cm m f θ == θ f is the focal length of the lens in cm. for small angles tan θ ~ θ Magnified f h tan = θ Simple magnifier. A simple magnifier with a focal length of 5.0 cm is used to view an insect. What is the angular magnification for a relaxed eye?
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## This note was uploaded on 06/03/2010 for the course PHYS physics 1c taught by Professor Smith during the Spring '09 term at UCSD.

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5.1OpticalInstruments - 5.1 Optical Instruments...

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