Inspired by various online, DIY USB microscope projects and this project on Hackteria.org in particular , I decided to have a go with creating my own USB microscope with different cameras and bits and pieces I had lying around. One of my primary objectives was to devise a way of focusing the camera that was simple, robust and didn't rely on complex assembly and machine tools.
I've also tried to design a project that is easily repeatable with young makers, and minimises the use of very sharp, very hot and very technical apparatus in construction. The project is also designed to be cheap i.e. do-able for under £10 ($15).
I'm due to run workshops demonstrating this project at the Brighton Mini Maker Faire in September 2013 so I'm hoping this instructable will help me stress test the approach ahead of then. So your comments and feedback are most welcome.
P.s. I know that the twist pack container might not be the easiest thing to get hold of, but its neat and works really well. I sourced my from Rose Plastics in the UK but had to purchase a minimum order of 100, which works if your planning to run workshops not so much if you're building a one off. I'm happy to post these out, at cost, on a first come first served basis to anyone interested. I'm interested in finding ways to replace the twist pack with more readily available parts, so any suggestions welcomed.
P.p.s Your computer may not automatically recognise the EyeToy camera used in this project (it's a playstation 2 camera model number SCEH-0004). If it doesn't, there are a number of plug-ins and web-cam applications that can rectify this.
If you use an Apple Mac, try the MacCam webcam drivers and CamSpinner to capture images and record video.
If you have a PC try this this tutorial blitzer.jimdo.com
Step 1: Parts and Tools
Parts, you will need:
- A USB webcam, I've used a Sony PS2 Eyetoy camera
- A plastic 'twist pack' container (I've used a DP50 050, from Rose Plastics)
- Some thick card, or mounting board with at least one white side
- An old toilet roll tube
- Some double sided sticky tape
- A 150ohm resistor
- One bright white LED (I took mine from an old torch)
- About 20cm of thin, coated wire (preferably two colours, can be multi-strand or single core)
Tools that will help:
- Soldering iron and solder (lead free)
- A scalpel and two blades - 1 new and one old blade
- A cutting compass (or normal compass if you don't have a cutting compass)
- A small Philips screwdriver
- Small flat or pinch nose pliers
- Wire strippers1
- A steel rule
- Hot glue gun
- Small, fine bladed saw, ideally a jewellers piercing saw
- Hole punch (for paper/card)
- Large pliers
Step 2: Prepare the Twist Pack and Cut the Card
Mark and cut a hole (about 35mm wide) in the top and bottom of the twist pack. (I heated an old scalpel blade and used it to gradually cut a hole by melting through the plastic, then smoothed the rough edges with a bit of sandpaper).
Take your card and cut three circles of card about 51mm wide.
Step 3: Webcam Disassembly
Now disassemble the webcam. First, unscrew the lens barrel (the black bit at the front) until it 'pops' out and keep unscrewing until the barrel comes out completely, then place to one side.
You now need to open the case. Locate the screws situated underneath a sticker on the bottom of the case, close to where the USB cable leaves the case. Remove the screws and carefully pull the case apart and remove the circuit board
Use a pair of snips to remove the microphone from the board and place it out of the way.
Step 4: Lens Barrel Disasembly
You now need to cut the lens barrel in halve to access the lenses. First, remove the 'cap' at the top of the barrel by gripping it with a pair of pliers (or gently in a vice) and then, with a second pair of pliers, twisting the cap. Remove the top 'lens' and place this and the cap to one side, you will need the cap again in a few steps.
Look for two thin lines or 'seams' on the barrel, make sure one of these is facing up so you can use it as a guide. Hold the barrel tightly (or use a vice) then using a fine saw (I used a jeweller's piercing saw), carefully saw down the seam until you have cut through the barrel (you are trying to separate the two halves of the barrel without sawing in to the lenses).
Repeat on the other side being careful to keep the two halves together so that the lenses do not fall out. Remove the small ring of plastic stuck and the little glass square that sits beneath to make it easier to separate the two halves.
Step 5: Reorder and Reassemble the Lenses
Carefully remove all the parts in the barrel and lay them out in order. Take a close look at the way the lenses are arranged (it may help to take a photograph so that you have a record of the order they are in). Pay particular attention to the curve of the lenses. You should see that one side appears more curved, or has a bigger 'bump', than the other, try to keep this bump to the front.
Discard the front lens (the one directly behind the cap) and reassemble the parts in the barrel taking care to not to get fingerprints on the lenses and ensuring that the 'curviest' side of each lens faces forwards (towards the cap). Now join the two halves and replace the cap you removed earlier (be patient with this and aim to keep the halves of the barrel aligned as you tighten the cap).
Screw the barrel back on to the circuit board. Test your camera by plugging it in to your computer and using it to view the pixels on your screen or monitor (you’ll need to hold the end of the barrel a few millimeters away from the surface if the screen). If you've configured the lenses correctly you should be able to see the red, green and blue components of individual pixels (see image below).
Step 6: Add a 'ledge' to the Inside of Twist Pack
Take your toilet roll and cut a straight line along its length with a pair of scissors, then flatten the tube out. Stick some double-sided tape along its length. Then trim at least four 5mm strips off the taped edge of the roll. Put these to one side.
Take the top of your twist pack and, using a compass, mark a line 6mm from its bottom edge. Using this line as a guide, carefully stick one of the strips of card to the inside of the twist pack to create a 'ledge'. Then add one more strip on top of this.
Take one of your cardboard discs and check that it will sit firmly on the 'ledge' you have just created. Build up the ledge with extra strips if you need to.
Step 7: Add an LED to Your Webcam (optional But Recommended)
Adding a light will help you to see specimens more clearly. Take an ultra bright LED (I got mine from an old LED torch) and solder a 130 ohm resistor to one of its 'legs'. Then solder one length of wire, 50-60mm long, to the resistor. Then solder another length of wire to the opposite leg of the LED so that you have two wires, a positive and a negative, that you can solder to your web cam (I used red and black wire so I could easily tell one form the other).
Look for the five pins attaching the USB cable to one end of the camera circuit board. Identify the 'ground', or negative pin (this should have a black wire attached to it) and solder the negative wire from your LED to this pin.
Now identify the positive pin (this should have a red wire attached to it) and solder the positive wire from your LED to this pin. Now when you plug the web cam in to the USB port on your computer the LED should light. If it doesn't, check your wires to ensure you have the polarity correct.
Step 8: Mount the Camera in the Twist Pack
Turn on your hot glue gun so that it has time to warm. Take one of your card discs and mark a point about 15mm from the centre of the disc then use a hole punch to create a small hole about 5mm in diameter. Now cut a hole in the centre of the disc just large enough for the widest end of the lens barrel (the 'capped' end) to pass through. You want this to be tight fit so try not to make it too large, about 12-13mm.
Remove the cap from the lens barrel (but keep the barrel attached to the circuit board so that it doesn't fall apart) and carefully insert it through the center of the disc (if the card has only one white side make sure this is facing away from the circuit board).
Replace the cap on the end of the barrel, and hold it flat to the card and secure with hot glue. Hold until everything is set, then pop the LED through the 5mm hole in the disc.
Take the USB cable and feed it through the top of the twist pack. Pull the cable through until the web cam sits in the tube and the card disc rests flat against the cardboard ledge on the inside of the tube. If the card feels loose you may want to add another strip of trimmed card.
Once you are happy that the card disc is in place, secure with a couple of strips of card stuck to the inside edge of the tube.
Step 9: Seal the Twist Pack and Finish Things Off
You’re almost done! Take another cardboard disc and draw a line through its center. Draw two more lines, 3mm above and below the center line. Using these lines as a guide, cut a slot out of the disc about 15mm long from its edge. Use this to hold the USB cable in place by slotting the flexible rubber piece at the end of the cable in to it. Do this before the next step.
Add some double sided tape or glue to the underside edge of the disc and fix it firmly to the top of the twist pack lid to seal it.
Cut a hole in the centre of the remaining cardboard disc, just smaller than the hole you cut in the bottom of the twist pack. Then, using some double sided tape or glue, firmly fix the disc to the bottom of the pack.
And that's it! You're done up-cycling a web cam into a super cool USB microscope with an easy to adjust focusing mechanism! Go grab yourself some things you'd like to exam up close and get exploring!
Step 10: Example Images and Video
- An small insect's legs/abdomen
- The edge of a coin
- The edge of a steel ruler (showing mm increments)
- A feather
- A small leaf
- A fingerprint
- Cotton fabric
- A small insect's legs
- The 'knurled' grip on a metal scalpel handle