Now two words about how I'm going to implement this pixel shifting.
Well, we are talking about micrometer precision level of displacement. I know that there is a trick of using handheld motion effect,
that allows to get this small sensor displacements (Fluke implemented this feature on some of their thermal imagers).
But don't like it at all, as handheld motion based super resolution (SR) is not accurate enough and also will not work in case of tripod mounting.
I'm going to use piezo actuators along with a custom XY-stage.
You can find a lot of info about piezo actuators and the physics of inverse piezoelectric effect. In two words this is crystal that can enlarge
for some small value if you apply some voltage. Piezo actuator behaves like a common capcacitor, and displacement value is equivalent to the charge level.
The dependency between the voltage and actual displacenent value is linear. It is possible to get even nm accuracy if desired.
ISC0901 has 17um pixel pitch, so we should select an actuator with a displacement value > pixel_pitch/2. I have selected AE0203D18H18DF, that has
max displacement level of 19.0 ±2.0um at 150V. Actuator dimentions are 18x3x2mm. The generated displacement force just blows my mind, it is about 200N (yes, two hundred).
I made some sketches of the XY stage and also some simulations. The thickness of the moving platform beams is about 0.8mm. If made of 6061 aluminium we need to
apply only 10N to displace the platform for about 16um, while the actuator can generate 200N.
Note that the movement level at attached gifs is amplified a lot, this is not the real value, as 18um displacement value is so small, that this is simply impossible to see it with an unaided eye.
I have never developed anything using such kind of XY-stages and piezo actuators, so suggestions and critics are welcome.
Advantages:
1. It is possible to significially increase the resolution. The gaps between active pixel area are so big, that pitch/2 shift will give a clear x4 resolution. More accurate shifting steps along with deconvolution image processing will increase the resolution even more, I hope to get a megapixel.
2. The construction will be fully backward compatible with whole other design, including focusing board.
3. This XY stage can be used with any other sensors, if attached over special adapter. New LWIR cores have even lower pixel pitch of 12um and we can still increase the resolution.
Disadvantages:
1. The piezo actuator, this piece of...
shi ceramics... costs around 100$. Yes, it is even more expensive that the FPGA. And...we need two of them for X and Y axis.
2. We will have to deal with high DC voltages under 150V, well this is a bit more dangerous than usual. There are special ICs for driving actuators with integrated dc-dc boosters that allow to get this high voltage.
3. Not sure, but probably the whole construction will be a bit more fragile, expecially because of the ceramic actuators, though I'm sure you wouldn't let it fall down)