microscope history and development (2) field of view and magnification check and go over...

Microscope History and Microscope History and DevelopmentDevelopment

(2)(2)

Field of view and MagnificationField of view and Magnification

Check and go over yesterday’s HW p Check and go over yesterday’s HW p 140-1140-1

Early Microscopes -Early Microscopes - Anton Van Leeuwenhoek Anton Van Leeuwenhoek

The father of microscopy, Anton Van The father of microscopy, Anton Van Leeuwenhoek of Holland (Leeuwenhoek of Holland (1632-1632-17231723).).

Anton Van Leeuwenhoek was the Anton Van Leeuwenhoek was the first to see and describe bacteria first to see and describe bacteria (1674), yeast plants, the teeming life (1674), yeast plants, the teeming life in a drop of water, and the circulation in a drop of water, and the circulation of blood corpuscles in capillaries.of blood corpuscles in capillaries.

Robert HookeRobert Hooke

In In 16651665, the English physicist Robert , the English physicist Robert Hooke looked at a sliver of cork Hooke looked at a sliver of cork through a microscope lens and through a microscope lens and noticed some "pores" or "cells" in it.noticed some "pores" or "cells" in it.

Hooke was the first person to use Hooke was the first person to use the word "cell" to identify the word "cell" to identify microscopic structures when he was microscopic structures when he was describing cork.describing cork.

Antique microscopesAntique microscopes (link)(link)

Technological Advances in Technological Advances in MicroscopesMicroscopes

Compound Light Compound Light MicroscopesMicroscopes

Uses lightUses light Has two lensesHas two lenses Magnification limited to 2000x (400x Magnification limited to 2000x (400x

at LHHS)at LHHS)

Transmission Electron Transmission Electron Microscope Microscope (TEM)(TEM)

Uses beams of electronsUses beams of electrons Magnification of 2 000 000xMagnification of 2 000 000x Has two limitations:Has two limitations:

Good only for thin specimensGood only for thin specimens Only dead cells can be observed Only dead cells can be observed

Scanning Electron Scanning Electron Microscope Microscope (SEM)(SEM)

Electrons are reflected from the Electrons are reflected from the surface of the specimen surface of the specimen

Produces a 3-d imageProduces a 3-d image Good for the thicker specimensGood for the thicker specimens Lacks the magnification and Lacks the magnification and

resolution of the transmission resolution of the transmission electron microscopeelectron microscope

MagnificationMagnification

Magnification = Objective lens X Ocular Magnification = Objective lens X Ocular lenslens

(4x, 10x, 40x)(4x, 10x, 40x)(10x)(10x)

Calculating the size of a Calculating the size of a specimenspecimen

binderbinder

Calculating the size of a Calculating the size of a specimenspecimen

Example under med. objectiveExample under med. objectiveObject size = Object size = Size of field of viewSize of field of view

Number of objects Number of objects across field of viewacross field of view

Object size =Object size = 1.72 mm1.72 mm 14 14

Object size =Object size = 0.1 mm0.1 mm