So webcams are quite fun, they take pictures, you can record videos, but what if you could take pictures of microscopic objects? This is a simple and reversible modification for a webcam which lets you take pictures of things far less than 1mm wide!
Step 1: The raw materials
You only need two things for this microscope:
1. A webcam with an unscrewable lens (I got a really cheap one for about £5 on ebay)
It is absolutely vital the webcam has an unscrewable lens, almost all do (and for most webcams this is actually the way you focus!).
Step 2: Dissasembling the webcam
This bit is dead easy, just unscrew the lens from the webcam! Once you have taken the lens out be careful not to get any dust on the CCD (the sensor in the body of the webcam) or on the back of the lens. Dust on either of these is very hard to clean off and can mess up the pictures.
Step 3: Reassembling the webcam
Now just use blu-tack to stick the lens back in the webcam, but backwards. Make sure you get a nice tidy fit, you want to avoid any light leaking around the edge of the lens. For me this was simple because the lens slotted neatly back into the body of the webcam. For some webcams you will have to use a thin sausage of blu-tac to seal around the edge of the reattached lens.
Step 4: Using the super-macro/microscope webcam
It is really simple to use, just point it at a (well lit) small object! To focus the image just move the webcam towards or away from the object, the lens will probably need to be a few millimetres away from the object. It is a bit fiddly to keep the webcam in position once it is in focus, I used blu-tack on the stand to help hold it still.
If you want to "zoom in" (increase the magnification) you have to move the lens further away from the sensor. The simplist way to do this is with a tube of paper or card stuck into the webcam body which you can put the lens in. Again, be careful with light leaks - black card or paper covered in tin-foil will be very good at blocking stray light.
Step 5: Measuring performance
To calculate the magnification of your new microscope you need to take a picture of something you know the exact size of. The easiest and most common small object to do this with is a pixel on a computer screen.
Take a picture of the pixels of your screen, then open the captured image in some photo-editing software. Measure how wide the image of one pixel is (in pixels), this is the magnification factor.
You can also calculate how big the field of view of the webcam image is from the ppi of your screen:
(25.4 / dpi) * n = fov
ppi is the "pixels per inch" of your screen, commonly 72.
n is the number of pixels that fit across the captured image.
fov is the field of view, measured in millimetres.
I have attached an example image from my modified webcam. Here the image of a single pixel is 130px across so the magnification factor is 130x. It is a picture of a 72ppi screen and 5 pixels fit across the image so the field of view is about 1.75mm!
Step 6: Some fun pictures
The pictures you can take are a totally different scale to any normal cameras ability, things look totally different when you can see them at such a huge magnification. If you can get a nice sample you should be able to see individual cells quite easily!
The images are of the edge of a 5p coin, the pixels on my camera's display and some paper!