Show HN: A large format XY scanning hyperspectral camera

juancn

Super cool, have you considered using galvanometers rather than moving the fiber around?

It should allow for faster scan rate (assuming the XY is the limiting factor).

bflesch

Well done, thanks for sharing.

May I ask a stupid question? In order to speed up this process you'd need to buy more of the broadcom spectrometers which are quite expensive.

So instead of buying more spectrometers, is there a way to use multiple fibre cables but make them different length so the single spectrometer takes longer to process the image, but the "exposure" of all fibre cables would be at the same time. Would it be possible to stack the signal in a way that the light of the first fibre cable arrives at the spectrometre, then there is a short pause, then the light of the second fibre cable arrives at the spectrometer, etc.

I imagine it like plumbing if you have two toilets attached to the same canalisation, and you flush both toilets at the same time but the length of each toilet's pipe to the main canalization pipe is done in a way that the water of the first toilet has fully passed before the water of the second toilet arrives.

To put it into numbers: toilet1 pipe length would be 1m and toilet2 pipe length would be 10m because before both pipes join and go into the canalisation. Water travels at a certain speed in the pipe, which would make this possible.

Can the same principle be used for fibre cables? If yes, it should be possible to construct a 100x100 fibre cable sensor matrix using large fibre cable lengths but only a single spectrometer.

Edit: I did some math and it seems the second fibre cable needs to be 40.000km long so that the singal of the first fibre cable reaches the sensor after the signal of the second fibre cable has passed the sensor (at 0.2s).

  speed of light      
  in vacuum 299.792.458,00 m/s    
  in fibre 66,00 % percent    
   197.863.022,28 m/s

  exposure per pixel 0,2 s

  exposure start time   distance traveled   
  fiber 1 0 s 0   
  fiber 2  0,2 s 39.572.604,46 meters 39.572,60 kilometers

Edit2: You can buy 1km fibre cable for 50€ , so only 2.000.000€ to test this

anfractuosity

The much faster way is to move a slit in front of a diffraction grating and use a 2D sensor behind that, that way you can obtain multiple spectral patterns simultaneously, see the video I mention at the start - https://www.youtube.com/watch?v=L_u8NqmgElU

bflesch

Thanks, sorry for asking if it was answered already. Would be very interesting to do some microscopy with this approach, as the video mentions medical use cases. There's been a lot of research on this I guess.

I wonder if hyperspectral cameras plus some ML could help discerning objects in microscopy without needing to stain them.

anfractuosity

Yeah definitely, I've not looked at papers relating to microscopy with hyperspectral cameras. That might be especially interesting with samples that fluoresce.

phubbard

The scan rate really limits the usability of this. Do you have any leads on planar sensors?

anfractuosity

A linear scanning mechanism would be a lot faster still than the XY approach.

I'm very curious how expensive sensors are though, that capture this data in a single shot, I've not seen any prices so far.