Phys 115 1st Edition Lecture 18Outline of Last Lecture I. Guest presentation: Prof. Sönke JohnsonII. Virtual images and objectsIII. Compound microscopeOutline of Current Lecture IV. Optics of the eyeV. Correction of visual defectsVI. Chromatic aberrationCurrent Lecture- The cornea, aqueous humor and lens form a compound optical element that produces a focused image on the retina.- The ciliary muscles change the shape of the lens to change the focal length of this opticalelement.- Regardless of the object distance, the image distance is always the same = distance from front of eye to retina.- Changing the focal length of the optical element allows the image distance to remain constant as the object distance changes (observing distant or nearby objects).- The refractive power of a lens is the inverse of its focal length: o P = 1/fo Unit = diopter- A lens with positive refractive power (positive focal length) converges the light, one with negative refractive power (negative focal length) diverges the light.- The myopic eye is too long for the focal length of the lens: the image is focused in front of the retina even when the focal length of the lens is at its longest (relaxed).- The hyperopic eye is too short for the focal length of the lens: the image is focused behind the retina even when the focal length of the lens is at its shortest (fully contracted).- Chromatic Abberationo All materials have an index of refraction that depends on the wavelength of light.o The focal length of a lens depends on the index of refraction of the material of These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.which it is made.o Different wavelengths are focused at different distances from the
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