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Lesson 3 Microscopy

  Invention of the Microscope


Microscopes have been around in one form or another for hundreds of years.
The first microscope was believed to have been invented by Hans and Zacharias Janssen in 1595. This first microscope was not very strong, but it opened the door for other scientists to start creating their own stronger microscopes. As you read in the previous lesson, both Robert Hooke and Antoni van Leeuwenhoek built their own handmade microscopes to discover the cell. This occurred just 70 years after the Janssens’ invention.


© Wikimedia Commons
A3.3 Hooke’s three-lens microscope
These early microscopes were a type of light microscope called a compound light microscope. A light microscope uses light through lenses to magnify the object. A compound light microscope uses a set of two or more lenses to produce a larger image. The images seen by these microscopes were not very clear and lacked detail. However, it was this type of microscope that was used to discover the cell itself, as well as the different structures found within the cell. As scientists were able to produce higher quality lenses, they were able to create an image that was both more clear and detailed.


© Wikimedia Commons
A3.2 Schematic of Janssen’s microscope

  Read This

Please reread pages 243 to 244 in your Science 10 textbook. Make sure you take notes on your readings to study from later. This time, you should focus on the microscopes the scientists used and how they differed. Remember, if you have any questions or you do not understand something, ask your teacher!

  Practice Questions

Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

  1. What were the main differences between the microscopes that Hooke and van Leeuwenhoek used? Which one worked better?

    Both scientists used handmade microscopes; however, Hooke’s microscope used three lenses. The light was concentrated on the object being studied by using a glass flask filled with water. Van Leeuwenhoek’s microscope was a simple microscope, meaning it used only one lens. It was small looked similar to a magnifying glass. It did not include a light source. Van Leeuwenhoek’s microscope worked better, as he was able to make higher quality lenses that did not blur the image. The lenses in Hooke’s microscope were of poor quality, so when you tried to see through more than one, all the imperfections added up, making a very blurry image.