Microscopes Anton van Leeuwenhoek and his Microscope Parts

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Microscopes Anton van Leeuwenhoek and his Microscope

Microscopes Anton van Leeuwenhoek and his Microscope

Parts of the Microscope head ocular arm rotating nose piece objective lens mechanical stage

Parts of the Microscope head ocular arm rotating nose piece objective lens mechanical stage course adjust stage condenser mechanical stage controls light source fine adjust base Power switch and light control locations vary.

How an image is formed by a microscope

How an image is formed by a microscope

Working distance is the distance between the specimen and the magnifying lens.

Working distance is the distance between the specimen and the magnifying lens.

Depth of field is a measure of the amount of a specimen that can

Depth of field is a measure of the amount of a specimen that can be in focus.

Magnification is a ratio of the enlargement (or reduction) of an image (drawing or

Magnification is a ratio of the enlargement (or reduction) of an image (drawing or photomicrograph), usually expressed as X 1, X 1/2, X 430, X 1000, etc.

Magnification and resolution are terms used frequently in the study of cell biology, often

Magnification and resolution are terms used frequently in the study of cell biology, often without an accurate definition of their meanings.

Resolution is the ability to distinguish between two points. Generally resolution increases with magnification,

Resolution is the ability to distinguish between two points. Generally resolution increases with magnification, although there does come a point of diminishing returns where you increase magnification beyond added resolution gain.

How an image is formed by a microscope

How an image is formed by a microscope

How the image appears

How the image appears

Determining field size As the total magnification goes up, field size gets smaller. You

Determining field size As the total magnification goes up, field size gets smaller. You can measure field size directly at low magnification. However, at higher magnification you won’t have a sufficiently precise measuring instrument. So then what? You can calculate field size from what you know about the relationship between field size and magnification.

Calculating field size Diameter of field A (known from direct measurement) X Total magnification

Calculating field size Diameter of field A (known from direct measurement) X Total magnification of field A = diameter of field B (this is the unknown) X total magnification of field B You can rearrange the terms to produce the following equation: diameter of field A X total magnification of field A = diameter of field B total magnification of field B Therefore: If field A = 2 mm in diameter at 50 X total magnification And the total magnification of field B = 100 X then Diameter field B = 2 X 50 = 100 = 1 mm 100

But, there is another way! The diameter of the field is inverse to the

But, there is another way! The diameter of the field is inverse to the magnification! (see slide 11) What this means is that if you increase the magnification by say a factor of four (four times), the field size will decrease by the same factor. Example: The field diameter at 100 X is 2 mm. Go from 100 X to 400 X, an increase of 4 times. The field diameter is decreased 4 times. (Simply divide by 4!) 2 mm = 0. 5 mm 4

Illustrations of microscope observations Drawings of specimens observed under the microscope should always include

Illustrations of microscope observations Drawings of specimens observed under the microscope should always include the following: • Title • Total magnification • Labels of interesting features

Example of a proper illustration plasma membrane nucleus Epithelial cells from a cheek Total

Example of a proper illustration plasma membrane nucleus Epithelial cells from a cheek Total magnification - 400 X

Parts of the Microscope This is the model of scope used in JH 219

Parts of the Microscope This is the model of scope used in JH 219

Get to Work!

Get to Work!