Introduction to the Microscope World Book Online Microscopes

Introduction to the Microscope World Book Online: Microscopes

Objectives • Investigate the purpose for using a microscope. • Learn how the microscope has evolved. • Develop a basic understanding of the parts of the microscope. • Use a microscope effectively (viewing prepared slides).

Purpose • Micro - “very small” • Scope - “to look at” • Tool allows scientists to make things look larger than the actual size. Hooke's drawing of a flea from Micrographia Size and Scale Example Image acquired from http: //www. roberthooke. org. uk/micro 1. htm

History - Timeline 1595 - Hans and Zacharias Janssen (Dutch) • First compound microscope • Used lenses (curved pieces of glass) to bend light rays – Makes enlarged image Lenses were poor Images blurred/distorted Information: Hans and Zacharias Janssen I Image acquired from http: //micro. magnet. fsu. edu/primer/museum/janssen. html

History - Timeline 1660 - Robert Hooke (English) • Improved upon the compound microscope • 1665 - Observed a slice of cork (parts of a dead cell) » The cork appeared to be made up of tiny, empty chambers » Reminded Hooke of rooms in a monastery called cells » The word cell comes from the Latin cella, a small room. Information: Robert Hooke

History - Timeline Pond Water Animacules 1683 - Anton van Leeuwenhoek (Dutch) • Father of Microscopy • Designed/used a simple microscope to study pond water • Saw tiny living organisms in the water – Named animacules - “tiny animals” • First person to observe living cells • Specimen magnification-266 x Information: Anton van Leeuwenhoek Image acquired from http: //www. essentialvermeer. com/dutch-painters/dutch_art/leeuwenhoek. html

History - Timeline 1886 – Ernst Abbe (German) • Modern Compound Light Microscope • Discovered the mathematical formula – Called the Abbe sine condition – Lens must satisfy certain conditions to form a sharp image, free from the blurring or distortion – Specimen magnification-1000 X Magnification of Various Items Information: Ernst Abbe

History - Timeline 1933 – Ernst Ruska (German) • Transmission Electron Microscope (TEM) • Nobel Prize Physics - 1986 • Makes images by sending electrons through a very thinly sliced specimen • Can only examine dead specimens • Useful for viewing cell structures Information: Ernst Ruska • Magnifies up to 500, 000 x

History - Timeline 1965 - Scanning Electron Microscope (SEM) • 1 st commercial SEM produced • Sends a beam of electrons over the surface of the specimen, rather than through it • Result: Detailed 3 dimensional image of specimen’s surface • Magnifies up to 150, 000 x

SEM Image acquired from http: //www. ecointerface. com/wp-content/uploads/2011/09/Screen-shot-2011 -09 -13 -at-11. 15 -AM. png

History - Timeline 1981 – Scanning Tunneling Microscope (STM) • Measures electrons that leak from the surface of the specimen • Can see individual molecules on the outer layer of a cell • Magnifies up to 1, 000 x Image acquired from http: //www. uta. edu/nano/facility. php? id=55&cat 2=STM

STM Image Mapping Molecular Orbitals Image acquired from http: //www. icmm. csic. es/spmageview. php? id=150

Magnification Image acquired from http: //www. cmog. org/article/quest-see-more-glass-lenses

Parts/Specifications Eyepiece Body Tube Revolving Nosepiece Objective Lens Stage Clips Diaphragm Light Arm Stage Coarse Focus Fine Focus Base Parts of a Compound Microscope: Parts and Specifications

How to Use 1. Carry with 2 hands: – – 2. 3. 4. 5. 6. 1 hand on the arm; one hand on the base Carry close to the body Remove the cover. Plug in the microscope; turn on. Place the excess cord on the table! Set stage in its lowest position. Always start with scanning (lowest) magnification.

Objectives • Each objective will have a written magnification. • The ocular lens (eyepiece) has a magnification. • The total magnification is the ocular x objective. Objective Magnification Ocular lens Total Magnification Scanning 4 x 10 x 40 x Low Power 10 x 100 x High Power 40 x 10 x 400 x

How to Use 1. Place the slide on the microscope stage. – – Adjust the specimen directly over the center of the glass circle on the stage (directly over the light). Do not use the stage clips. 2. Raise the stage to its maximum WITHOUT touching the objective to the slide. 3. Focus the lens on the specimen using the coarse adjustment. – Scanning magnification (4 x)

How to Use 4. SLOWLY lower the stage while looking through the eyepiece. – – – Take off eye glasses. Move closer if you see only your eyelashes Close or cover the opposite eye! 5. Adjust the diaphragm while looking through the eyepiece. – – MORE detail is visible when you allow in LESS light! Too much light will give the specimen a washed-out appearance.

Microscope Care • • Always carry with 2 hands Do not force knobs Always store covered Cord should be completely on the table • Only lens paper should be used to clean the objectives

Virtual Microscope • University of Delaware - Microscope Practice

Quiz Practice • Quiz: Parts of the Microscope