THE MICROSCOPE

HANS & ZACHARIAS JANSSEN Made the first compound microscope in 1595

ROBERT HOOKE The “father of microscopy” Looked at cork under the microscope in 1665 Responsible for the term “cell” Added light to the compound microscope

Anton van Leewenhoek made the first simple microscope in 1675 one of the first scientists to see microorganisms

COMPOUND LIGHT MICROSCOPE Uses natural or artificial light Composed of two or more lenses

OCULAR LENS lens closest to the eye usually has a power of 10X

OBJECTIVE LENS Lens closest to the specimen a)Scanning lens – 4-5 X b)Low power lens – 10X c)High power lens – 40-43X d)Oil immersion lens – X

PARTS OF THE MICROSCOPE

STEREOMICROSCOPE Uses light reflected off the surface of the specimen Often called a “dissecting scope” Magnifies 5X to 200X

MAGNIFICATION Magnification is the optical enlargement. It is calculated by multiplying the ocular power by the objective power. OCULAR POWER OBJECTIVE POWER MAGNIFICATION SCANNING10X4X40X LOW POWER10X 100X HIGH POWER10X40X400X OIL IMMERSION10X100X1000X

RESOLUTION Resolution is the ability of a microscope to show fine detail of a specimen.

ELECTRON MICROSCOPES Types Transmission (TEM) Scanning (SEM) Expensive Specimen cannot be alive

SCANNING ELECTRON MICROSCOPE Uses a beam of electrons over the surface of the specimen Invented in the 1950’s Produces a 3-D image of the specimen Magnifies 10X to 500,000X

TRANSMISSION ELECTRON MICROSCOPE Uses a beam of electrons through an extremely thin sample Invented in 1930’s Magnification of specimen up to 1 million X

SPECIMEN PREPARATION Live specimens can only be viewed with a compound light microscope. The specimen must be very thin because light must be able to pass through it. Specimens may be treated with stains (dyes) to make details easier to see.