Introduction
Goal of the workshop was to repurpose a possible cheap USB webcam into a microscope. Max Neupert, the organizer of this workshop, told us how to achieve this and instructed us throughout the winter term 2012/13.
The basic concept is pretty simple: just disassemble the camera, mount the lens upside down and shoot some great photos with the new microscope.
Disassembling the Camera
The "Hama PC-Webcam AC-150" served as a basis, which costs about € 5 when ordering via Amazon. It has a resolution of 640x480 pixels and six LEDs to lighten the scene. Beyond this, the camera supports UVC (USB Video Class), which is important for viewing live images directly on the screen.
As mentioned before, the first step was to disassemble the camera. After cracking the case, six LEDs had to be removed. In order to do so, we had to heat the solder at the back side of the PCB (printed circuit board). The last important step was to mount the lens with hot glue upside down onto the PCB. If needed, one can solder flex (in German: Litze) with the remounted LEDs back on the PCB for beeing able to lighten the specimen.
Unmounted from stand
After cracking case (1)
After cracking case (2)
Unsoldered LEDs
Unmounted lens
Remounted lens
Flex with LEDs
The resulting microscope has a magnification area of 0.35 mm x 0.46 mm. This can be calculated by counting the visible pixels of a display with known ppi-specification. In my case the microscope shows 3x4 pixels with a length of 0.117 mm per pixel (HTC HD2 has 217 ppi).
Building a Case
Since a microscope is designed to show very small objects, it is not appropriate to hold the camera in the hand because of uncontrollable hand movements. Therefore, we needed to build a case that holds the microscope and gives the possibility to do little adjustments in height (that is our zoom).
My approach basically consists of two sleds that lie on one another where the contact surface is a plane in the angle of 15 degrees to the table. Pushing the lower carriage to the left will force the upper carriage to move upwards. The first image on the right shows a technical side view drawing, the second one shows a rendered image.
After building a prototype out of Balsa wood, I was able to prove that the construction works fine. However, some minor changes have been applied to the model before printing the parts with a RapMan 3D printer. In the image below, that shows the two printed sleds carrying the microscope, one can notice that a M4 threaded rod was stuck through the lower sled and two counter nuts were fastened at each side of the sled, whereas the original plan was to have a screw head lying in a little pocket.
A M4 thread has a pitch of 0.7 mm, which means that one rotation about its own axis will move the lower sled 0.7 mm and consequently the upper sled about 0.2 mm. As a result, the microscope can be adjusted very fine in its height.
Note: Unfortunately the 3D printer became damaged; so, the case itself is built out of Balsa wood and could not be printed during this course. The sleds were printed before the printer fell off the table.
Sleds at upper position
Sleds at lower position
WebcamCapture Application
Because of the lack of simple applications which just show the current image of the webcam, I wrote a little program that does exactly this.
The application can be downloaded here, but note that the program only runs under Windows and .NET Framework 4 has to be installed.
Usage:
- Space bar - Save image to file
- R - Record video to AVI file
- N - Add suffix to filename (so you can identify your object later on)
- Escape - Exit application
First images
Here are my first images taken with the microscope. Unfortunately, on almost all images one can see a blob (probably hot glue). I decided to do some better work with a totally new camera, but this one produced even worse images since it had a lower resolution and magnification.
Display of HTC HD2
Glass of iPhone
Paper shred
Hair
Knife blade (1)
Knife blade (2)
5 Euro note
Onion skin
Here is a video of moving bubbles in a drop of water of the river Ilm.
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First artistical tries
In her talk about the basics of microscopy, Adriana showed us some nice images captured with microscopes such as the ones on this site. Since I liked the way the artists colored their specimen, I asked myself how to achieve a similar effect with possible cheap equipment.
So, I considered to dye sugar, salt and meal with food coloring and then take gaudy images of it. In the photo to the right, one can see the condiments drying at a radiator after coloring.
Here is a gallery of some images I shot:
Usual sugar
Blue colored sugar
Red colored sugar
Sugar in multiple colors
Usual salt
Blue colored salt
Yellow colored salt
Salt in multiple colors
Usual meal
Green colored meal
Red colored meal
Meal in multiple colors
Some of the images are nice-looking, but after all I am not satisfied with the results. One big problem I noticed when taking these photos, is that the camera has an automatic white balance; so, it was the best to always keep the Petri dish in motion, which made it quite hard to capture good photos.
Microscopic World: Waterdrops
When playing around with the colored condiments, I wondered how it would look like when one gives a drop of water onto salt and sugar. Here is the result:
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