Topic 6: Use and Care of the Microscope

Light microscope

________ has- 200 nm resolving power.

Electrons

________ have a short wavelength therefore excellent resolving power.

Simple microscopes

early microscopes that consisted of biconvex lenses (essentially magnifying glasses)

Brightfield compound microscope

shows dark objects in a bright field

Condenser

consists of several lenses that concentrate light on the slide by focusing it into a cone; contains iris diaphragm

Monocular microscope

has only one ocular lens

Binocular microscope

has two ocular lenses

Course adjustment

used for focusing with low-power objectives

Fine adjustment

used for focusing with the high-power and oil immersion lenses

Field of vision

area seen through a microscope

Resolution, or resolving power

ability of lenses to reveal fine detail or two points distinctly separated

Refractive index

the amount of light bends

Focal point

light rays bent to converge, where image is formed

Spherical abberation can be minimized by use of iris diaphragm

eliminates light rays to the periphery of the lens or by a series of lenses resulting in essentially a flat optical system

Chromatic abberration

multitude of colors in field

Who invented the microscope?

Zacharias Janssen

Who first used a microscope to examine microorganisms?

Antoni van Leeuwenhoek

What are simple microscopes?

early microscopes that consisted of biconvex lenses

What microscope shows dark objects in a bright field?

bright-field compound microscope

What is a condensor?

consists of several lenses that concentrate light on the slide by focusing it into a cone

What is a iris diaphragm?

controls the angle and size of the cone of light

What are the two types of lenses on a microscope?

objective and ocular

What is difference between monocular and binocular microscope?

monocular has one ocular lens and binocular has two ocular lenses

What is used for focusing with low-power objectives?

course adjustment

What is used for focusing with high-power and oil immersion lenses?

fine adjustment

What is the area seen through a microscope?

field of vision

How is total magnification calculated?

multiplying magnification of ocular and objective lenses

What is resolution? (or resolving power)

ability of lenses to reveal fine detail or two points distinctly separated

Small wavelengths ___ resolving power

increase

What does electron microscopes use as light source?

electrons

Which microscope has the best resolving power, light or electron?

electron

increase in numerical aperture ___ resolving power

increases

What is the function of the wavelength of light used and a characterisitic of the lens system?

numerical aperture

What is refractive index?

amount of light bends

Why doesn't light ray defract with use of immersion oil?

immersion oil has same refractive index as glass

What is focal point?

light rays bent to converge (where image is formed)

What is spherical abberration?

multiple focal points that are a result of curvature of the lens

What can minimize spherical abberation?

using iris diaphragm

What is chromatic abberration?

multitude of colors in the field

How can chromatic abberration be minimized?

use of blue filters, use of corrected lens, or use of one wavelength light source

What does a compound microscope require?

a light source

A rheostat ajusts what?

intensity of light