I bought a Seek Thermal camera pretty much as soon as it was available for pre-order and it is awesome! It's a fantastic troubleshooting tool for electronics. If you go out and buy a Seek Thermal camera now they improved the lens design compared to mine. Unfortunately I don't think the new ones will fit in the housing I made.
Why mount the phone outside the car instead of inside? Glass is not transparent at the wavelength of thermal energy, so the camera can't see through it. It just measures the windshield temperature. Simple solution? Mount it outside.
Finding Thermally Transparent Material
I wanted to cover the lens with something to protect it from road debris, but it needs to be thermally clear. Initially my searches only returned expensive exotic materials that were way outside my budget. The normal use case for a thermal window is on expensive factor equipment. When a technician needs to measure temperature of something without opening a door, you use a very expensive windows made from GaAs (Gallium Arsenide) or ZnSe (Zinc Selenide). Here is a table of thermally transparent materials I found:
After quite a bit of research I discovered that plastic grocery bags are quite transparent to thermal energy. The only problem is that the matte finish of the plastic in grocery bags slightly blurs what you see through them. I started looking for a thin plastic that had good thermal transparency and good optical clarity. I tested all the thin plastic that I could get my hands on. I ended up with a photo sleeve.
The lens shield was laser cut from one of these:
http://www.amazon.com/dp/B001WAVT8O/ref=pe_385040_127541850_TE_item. According to amazon it is made of "Biaxially Oriented Polypropylene (BOPP)". Never heard of that before, but it works quite well. Not to mention that it also laser cuts quite well.
The lens cover material was the most challenging part of the build to nail down. The next most tricky thing was the geometry of the case design. It mounts to the hood of the car which curves down towards the front wheel and down toward the front bumper. the bottom of the case. It took a couple of iterations to get the curves right.
The result is that the camera is pointed straight forward and the horizon shows up flat as you'd expect.
The video does a good job of showing assembly, installation and operation. I also added captions with some of the insights that I have from my experience with the setup so far. The big question though, is this actually a good idea? Is it useful?
Well, kind of.
You aren't going use it to not hit a deer. You will be able to see the deer on the thermal display, you just won't see it until you are hitting it. There is a 1 to 2 second lag in the displaying of the thermal video, and the 5 to 8 FPS is kind of jumpy. And when the deer is far enough away that you should start braking it is too small to make out well on the display. That is mostly from the 36 degree field of view of the camera. The new Seek Compact XR, with it's 20 degree field of view would probably be a lot better.
As I noted in the video, the guy in the cross walk is difficult to see because the ambient temperature is so close to his body temperature. So looking for living creatures based on body heat is only effective when it is cooler out.
On the plus side, there is a whole new set of information available to the driver about the world outside. You can see in total darkness, and I could definitely see further down a dark street on the thermal camera.
I think that I would have better results with the new Seek "Compact XR". Maybe Seek will read about my project and decide to send me an XR so I can update my 3D models and try again. That would be sweet.