Lecture 29 - Lecture 29. Fri 4-8-11 Lab #5 Full...

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Lecture 29. Fri 4-8-11
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Lab #5
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Image Plane Collector Lens Just in front of the microscope’s lamp is a lens that magnifies and projects an image of the lamp’s filament toward the condenser. The collector lens concentrates the lamp light for Köhler illumination. Field Iris This iris controls the size of the area of illumination on the specimen. In setting up Köhler illumination, the field iris is observed along with the specimen. Condenser The condenser concentrates light from the filament image onto the specimen plane. Full Illumination Pathway, including condenser Objective The objective gathers light from the specimen and magnifies the image. Condenser iris This condenser diaphragm varies the breadth of the cone of light that illuminates the specimen
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Two aspects of the light 1. Illuminating light. The light before the specimen . The light from the lamp is collected by the condenser lens and optimized by: A. Focusing the condenser B. Adjusting the field diaphragm C. Setting the condenser iris 2. Diffracted light. The light from the specimen is diffracted and viewed through the ocular A. Low spatial frequency diffraction from a large object B. High spatial frequency diffraction from fine structural detail
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Light Diffracted by the Specimen Low spatial frequency diffraction: The bending of incident light rays at angles that diverge slightly from incidence (0) due to large structural detail within the specimen. High spatial frequency diffraction: The bending of incident light at highly divergent angles due to fine structural detail within the specimen Incident light rays
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What’s the point? To see fine detail, we need to collect high spatial frequency defracted light
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Different objectives can gather different amounts of light A 100x objective can gather a wider cone of light than a 4x objective A 4x objective can collect low spatial frequency diffraction from a large object but not much high spatial frequency diffraction from fine detail
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This note was uploaded on 07/26/2011 for the course BIO 201 taught by Professor Janicke during the Spring '08 term at SUNY Buffalo.

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Lecture 29 - Lecture 29. Fri 4-8-11 Lab #5 Full...

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