Density Meter

I found this in (drawing above) "The Amateur Scientist" by C.L.Stong - chapter on How to Cultivate Harmless Bacteria. It is a light meter for measuring the density of bacterial growth.

Using the items found in the above picture I hope to build this for my use in measuring yeast growth in my experiments. I have collected a box (this one is wood, it can be card board or plastic), the cover should keep out any light. I have a laser pointer as my light source (the original uses a light bulb, if the laser doesn't work, I will use a light bulb). A lens is used to focus the light beam, therefore, giving a more pinpoint concentration of light. A solar cell rated at 5 volts will measure the intensity of the light coming through the sample. The less the growth, more of the light reaches the panel. The volt meter will be connected to the solar panel which will give me my readings.

I will look into hooking it up to my homemade laptop oscillscope so I can record my measurements. I will post the finished meter later when I have worked it out.