Sensor Helmet Video Systems
Close, but no cigar…
I decided to purchase wide angle lenses for the 808-16 camera in large part to size restraints. I realized that installing an external lens was going to end up making the whole thing look like trash. Last week, the wide angle lenses arrived. This post provided the details on how to convert the lens. This is much cleaner than the modification I did to the stock lens. I used an X-Acto tool to remove the thread lock. Once out, I could see the filter. I sliced at the four corners and had no trouble prying out the filter. I did have some trouble removing the lens from the sensor at first. The forward lens cap came loose, instead of the entire lens assembly. By the time I realized it, a small lens popped out onto my work bench. Luckily, the bench was clear and I spotted it.
I knew I would have to re-focus the camera, so I used AMCap to stream video from the camera to my computer. I wanted to block out visible light, so I used a cut piece of floppy disk media. Once cut to size, I installed this into the forward portion of the lens assembly. After some adjustments to focus, it was ready for use.
I thought this was the last item remaining for the sensor helmet, so I started work on heat sinks for the processing boards. The Mobius camera uses a more intense processor to handle the 1080p video. From what I could gather on the data sheet, the processor handles functions that most folks take for granted. The raw image sensor data is noisy, blurry, and shaky. All of these problems are dealt with by the processor. A consequence is the processor runs hot and the stock Mobius has a heat sink built into the housing.
Since the housing is going to be removed to allow the process boards to be directly mounted in the helmet, I had a problem to work out. I found thermal conductive epoxy that I could use to glue square pieces of copper to the processing chips. I used a cut piece of 3/4 inch copper pipe for the material. Once that piece was cut, I sliced along the flat portion of the copper pipe with a grinder. Then I took a ball peen hammer and flattened out the copper. Next, I used diagonal pliers and cut the square portions out. Then I smoothed out the edges with a file. With all the pieces cut and ready, I mixed the epoxy and set the new heat sinks on the processing chips.
After a day of curing, I figured I better run a bench test to make sure it handles the heat. This is when I realized I didn’t have all my parts. The video extension cable I had only worked with the 808-16 camera. The Mobius camera had an additional 3 pins, so I went online and ordered it. It might be here by the end of September…bummer.
Anyway, I went ahead and did the bench test. I didn’t have a precise way to measure how well it worked, so I did it ad-hoc by touching the heat sink. Both the 808-16 and Mobius ran fine for 30 minutes of steady recording. My guess is the copper didn’t get hotter than 140 degree F. The video was good, with no signs of discoloration or dropped frames, I noticed this with my 808-26 due to over heating. Good to go.
Until the data cable arrives for the Mobius lens, the rest of the visual portion of the sensor helmet is on hold. I’ll need to center the FOV of both lenses before I fix them inside the helmet. I’ll be using a laser pointer to center them, once the last item arrives.
In the meanwhile, I can get started on the sensor and micro controller installation, as well as build the power pack. Until next time…