The microscope presentation

The microscope

A brief history

The first microscope

• 1st century AD– Discovery of transparent crystals that are thicker

at the edges: these made things look larger– From here, the term lenses was coined since these

crystal look like the seeds of a lentil– The earliest microscope had a 10 times magnifying

power: simple microscope with the lens at one end and a plate for the specimen on the other

The first microscope

• 1590– Zaccharias Janssen and his son Hans pioneered

experiments in using several lenses in a tube– By doing so, images were further enlarged

• 1609– Galileo heard of such experiments and worked out

the principles behind the use of lenses– Became the father of modern astronomy

The first microscope

• Anton van Leeuwenhoek (1632- 1723)– Made tiny lenses of great curvature– First to observe and describe bacteria, yeast, life in a drop

of pond water (around 1674)

• Robert Hooke– English father of microscopy– Observed cells found in a cork using a primitive

microscope (1665)– Reaffirmed Leeuwenhoek’s findings later upon

improvement of the microscope design

The first microscope

Magnifying vs. Resolving power

• The magnifying power refers to the capacity of an objective to enlarge or bring the specimen closer to the eye of the observer.

• The resolution or resolving power is the ability of the objective to provide clear details on the specimen being observed

Types of microscopes

• Simple microscope– Use of a single lens

• Compound microscope– Use of multiple lenses to magnify images

• Electron microscope– Invented by Ruska in 1933– Makes use of electronic beams to magnify specimen– Capable of magnifying objects up to 500,000 times

Sample

Letter o at 40x magnification

Letter o at 100x magnification

Letter o at 400x magnification

Sample

Letter o at 40x magnification

Letter o at 100x magnification

Letter o at 400x magnification

Objective lenses

Objective lenses

Objective lenses

Objective lenses: Oil Immersion

Objective lenses

Laboratory report requirements

• Answer all questions or provide what is being asked for

• Follow the format• Due on Thursday before 7:30

Third long test

• Friday: 1st part (class time) 2nd part (4:30 onwards)• Coverage– From the DNA until the microscopes

• First part (25 to 30 points) written• Second part (15 to 25 points) lab work• Tips– Be familiar with the parts of a microscope and its function