NEW ZEALAND TARANAKI

Build a Microscope

Jamie Fenton First Place winner, Senior Technological Development, 2006

Rescue and recycle old lenses; use PVC pipe and an old chemistry retort stand to build a microscope suited for junior students!


Abstract

I have designed, developed and constructed an inexpensive, high quality microscope which is safe and easy to use.

The study of small objects presents a difficulty to many junior science teachers since students need to be trained in the use of a microscope.

Multiple objective lenses, condensers, numerous focussing knobs, can confuse and be damaged with misuse.

A high quality microscope is often very expensive, and so few schools allow their junior students regular access to them.

I have solved this problem; my microscope is easy to produce, sturdy, gives high quality images, and even my seven year old sister can use it!

 

Materials

  • Old wood retort stand
  • 40mm X 40mm wood
  • 5mm MDF
  • 3 volt lithium battery
  • Ultrabright white light emitting diode
  • 25mm electrical conduit
  • 170mm PVC pipe
  • Computer ribbon cable
  • Screws
  • Eyepiece and objective lens from a broken microscope
  • Black spray paint
  • Coat hanger wire
First trial of the micrsocope made from an old wooden retort stand and clamps

The 170mm PVC pipe is cut so that the eye peice and objective will be the distance L specified (arrowed) on the objective lens.

 

Check for this value printed on the objective you are going to use and cut the pipe to length accordingly.

How to read the objective lens to cut a barrel of the correct length

 

Results and Discussion

This microscope was simple to build once I had finalised my design. The most difficult part of the design process was deciding how my microscope would be focussed. I had worked on a design in which the barrel had moved while the stage remained stationary, using a somewhat complex pulley system.

Another focussing system which I considered was a lever used to push the stage up. I decided against this system because of the resulting instability of the stage.

In summary, after trying various systems involving a pulley, lever, or wind on cable, I settled for the screw driven stage.

The finished microscope using a screw thread to raise the stage

My current design gives a reasonable level of stage stability and it is physically impossible to ram the objective through a slide. This is a major advantage over other microscopes due to the shape of the screw.

Because it runs on battery there is no danger of electrocution or tripping over cords. This makes it safe to use around small children, who would usually miss out on the experience of using a microscope.

Using a 3 volt button cell, the ultrabright LED is not bright enough to blind, eliminating the need for a mirror and sunlight. Unlike a bulb, the LED does not give off heat, thus the cell should last quite a while.

A light emitting diode is easier to use than a mirror

My microscope has few components, making it ideal for light transportation and easy storage, and also reduces the difficulty for the user.

Users will not be required to change objective lens, a process which can confuse some people, and in a traditional microscope can lead to the misuse of the oil immersion lenses, which are not required for most samples.

It is possible to change the objective lens relatively easily if necessary.

In finding the right way in which to position the eyepiece and objective lenses, I learnt that it was not critical to have the barrel exactly 170mm, which is a positive thing as it allows room for error.

My microscope magnifies the image 150X. I obtained this number by multiplying the value of the eye lens, 15X, with the objective lens, 10X. This is a good value for samples for junior students (i.e., crystals, fibres, plant cells, protozoa).

However, I would like to further improve my microscope with the addition of a proper switch and battery holder. While my current power system has the advantage of the cell being easily removed and changed, I would like to make it more permanent. I would also like to improve the slide clips, which currently have difficulty moving due to obstructions. I have no mode of moving slides other than by hand and this could be something I will include in my next model.

The prize winning home made microscope

 

Conclusion:

I have successfully engineered a microscope which even my seven year old sister can use without difficulty.

I built it using only laboratory leftovers which I found at home.

It cost me nothing to build and the image quality is as good as a $1700 Nikon microscope.

I think that this met the need for a microscope which is practical for use by junior students.

A TARDIS makes a great changing room to slip into something more comfortable...

Jamie never has to worry about running out of time for Science Fair projects...


FIND OUT MORE:-

  1. The interactive pages...discover how a microscope works
  2. Add a camera to the eye piece to capture photos from your microscope here
  3. Add a micrograph viewer so your friends can see too
  4. Look at these amazing electron microscope photos - the UGLIEST creature on the website is here

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