I want to install a USB camera at the focal plane of an instrument. This means putting the raw sensor at that location, so no lens or other focussing system is needed. The image on the focal plane is a 12mm diameter circle, so ideally I would use a sensor with a 12x12mm footprint, corresponding to 17mm on the diagonal. Somewhat smaller is also OK, say 9x9 or 10x10.
It’s not hard to find industrial USB cameras as boards or modules with such large sensors, but they are very expensive. The inexpensive boards have 3 x 4mm or similar size sensors.
I was wondering if anyone here can point me to less expensive large sensor USB cameras that work well under OpenCV. Note that I don’t need large pixel counts, 1024^2 or more is OK. Monochrome would also be OK. Low frame rates are also OK.
lowish triple digit dollars or thereabouts, I believe. should be worth it to you.
sensor cost scales strongly with sensor area. if you only look for webcams, you will not find sensors of the size you need.
you could see if you can scare up an old used DSLR with HDMI output (“clean feed”, no UI drawn on top of the picture). those usually have big sensors. take the lens off. you’ll see the sensor. then attach a HDMI-USB dongle, which are rumored to be as cheap as 5 bucks.
is that a typo? I’ll assume that. if that was supposed to be 1024 square… all “Full HD” sensors can do that and no camera maker would be caught dead selling a DSLR with less, even 20 years ago.
Thanks for the advice. Yes, the pixel count was a typo, I’ve edited and fixed it. The point is that I do not need a lot of pixels (1024^2 is fine) but I need a big sensor.
I like the idea of tearing up an old DSLR with an HDMI output. Can anyone recommend a specific model?
PS: I just had a look and see what a good idea this is. For example a Canon EOS 20D costs very little on the used market. It has a CMOS-Sensor APS-C 22,5 x 15,0 mm with 8 Mpixels and a pixel pitch of 6.4 microns. I’ll need to see what sorts of outputs it provides…
PPS: I need to mount the sensor on the focal plane of an instrument, which means that it will need to be removed from the camera body, but presumably kept attached to the various bits of electronics and switching that are needed to keep it functional. Does anyone know if there are some older smaller cameras (rather than the bulky DSLRs) that have decent sensors, and where the sensor is close to the lens mounting flange?
Maybe you could use a lens of some sort (something with a larger diameter optic and long focal length - maybe a telecentric lens?) so you could get the area coverage you need but with a smaller sensor.
Thanks for the link, I have not seen 1d and 2d position sensors like that before. However I can’t use them in my application.
I’ve experimented with using a lens to focus the light on a smaller sensor, but this adds quite a bit of complication. The problem is that the system has two foci, one for a light source and a different one for the virtual image. Putting the sensor on the focal plane eliminates several issues.
On the other hand I may have found another approach that allows me to use a smaller sensor, so I’m looking into that now.