wafer.space Community - motorized scope strobe mode capture

2:54 p.m.

I'm actually surprised you haven't yet tried pulsed illumination to combat the severe slow-down of pausing at each position.... If you have a PI5 on the camera it should manage over 20 fps.... (at full resolution) https://forums.raspberrypi.com/viewtopic.php?p=2227660#p2227660. The trick would require rather effective strobe-centric illumination though; for continuos motion along the 3040px direction you'd be looking at flashing for about 13 microseconds duration with a full frame worth of photons. "Just" needs pulse-shaped excitation or an active reverse current pulse on end-of-pulse to rapidly stop the glow. Oh, also, that's math with 0% overlap between images; I'm assuming you're doing substantial overlap for post-processing alignment and such purposes. The harder part I guess is that 99.9% to 99.99% of light need to happen within that short single-line-duration of the frame. So dark surroundings and driving the strobe to be very much dark at the other times. Thankfully I think a simple series resistor (current limiting) drive with a simple half-bridge would do. The active-low drive discharges the stray capacitance in the LEDs and the rest of the circuit to prevent them from emitting light. Also probably annoying to look at with this meager frame rate the only-half-the-lanes setup causes

@namibj - I have the random idea of treating the microscope / camera more like a satellite continuously moving over the earth and using a lot of the signal processing those guys use to generate images.

Tim 'mithro' Ansell

@namibj - I have the random idea of treating the microscope / camera more like a satellite continuously moving over the earth and using a lot of the signal processing those guys use to generate images.

I mean you can do some of that

12:34 a.m.

but there are some issues about noise scaling with signal amplitude of a pixel that discourage shoving the deblurring to software

12:35 a.m.

but like you can move it continuosly

12:36 a.m.

this kind of strobe isn't hard for the tiny spot size of a microscope

12:36 a.m.

(I don't think it exceeds what LEDs can be reasonably convinced to output, even with fairly poor illumination optical economy.)

12:37 a.m.

the ultra mode of strobe light are diode-pumped Q-switched Nd:YAG

12:38 a.m.

they do from 10 to 1000 Hz and 5~50 ns pulse duration at pretty high efficiency

12:38 a.m.

but that's not needed for these lower frame rates

There is a bunch of fancy maths that lets you take the continuous stream of the pixel data, the information about the rough velocity, and the relative pixel position to do super resolution / reverse convolution reconstruction of what things must look to produce the pixel data.

Like I'm talking about fitting about 500x more LED die in there as would normally be needed, but with overall less harsh thermal management solution.

Yeah you can do, it's just that some of the sample noise of the image sensor with a photodiode well that integrates during sampling interval is increased at increased count

12:40 a.m.

which blurs over

@namibj - Yeah, you are talking about a different thing to what I'm talking about. I'm just rambling

yeah doesn't need to be 1:1, can do 1:10 easily

Microscope objectives are expensive

I've done a bunch of research years back in multiframe blind deconvolution

Tim 'mithro' Ansell

Microscope objectives are expensive

well this doesn't need one to be free of distortion

12:43 a.m.

just flat field and low enough chromatic abberation

12:43 a.m.

if you use 3 pulses of colored LED and a monochrome sensor you don't need the low chromatic abberation but your color repdouction will be wonky

This sounds really useful, and I am looking forward to seeing such a system running. Unfortunately, I don't have neither time nor energy to invest into one more project at time moment