3 ms·

Instead of a laser gauge, you could try using a camera hooked up with some edge detection software and use that to estimate the width. It probably wouldn't be a

Instead of a laser gauge, you could try using a camera hooked up with some edge detection software and use that to estimate the width. It probably wouldn't be as accurate, but it would definitely be cheaper.

nitrogen 6y ago
You'd be looking at very subtle variations in the color of single pixels, so you might as well just use a single optical sensor and light source into a single high res adc, using intensity to measure thickness. At some point dust in the air will be a limiting factor.
- londons_explore 6y ago
  You'd make the filament go slightly diagonally across the field of view of the camera, and then you'd have thousands of part-filled pixels. As long as your material is consistent (no bubbles, shiny spots, etc.), You should be able to build a very accurate sensor this way.
- elcritch 6y ago
  For high accuracy, the brightness is really more the limiting factor, as most of the edge finding/binarization algorithms use a intensity factor for cutoff. I used camera measurement for small pieces of tissue samples in biomechanical measurement (~1mm x 5mm). We had a small window in our lab, and cloudy days would distort measurements. I solved it mostly by going to a SLDR camera from a handheld and a backdrop with a type of luminance chart. Much more accurate than calipers for soft squishy (and wet) samples. See [1] Figure 2E (pg 22), you can average out small variations pretty readily. 1: https://pdf.sciencedirectassets.com/274145/1-s2.0-S1751616116X00112/1-s2.0-S1751616116304477/Jaremy_J_Creechley_Creep_Fracture_2016.pdf https://pdf.sciencedirectassets.com/274145/1-s2.0-S175161611... Though your idea of a light source and adc could work well if you put it in a darkened enclosure. It’d probably require a bit more hardware design or tuning but the software / microcontroller side would b simpler. A RPi PiCam with a macro lens would work well too, but the reverse with less hardware tweaking and more software.
- econcon 6y ago
  I found this video https://youtu.be/kpsN78mQ6YY https://youtu.be/kpsN78mQ6YY They use a laser pointer to measure width of a hair.

nitrogen 6y ago

You'd be looking at very subtle variations in the color of single pixels, so you might as well just use a single optical sensor and light source into a single high res adc, using intensity to measure thickness. At some point dust in the air will be a limiting factor.

londons_explore 6y ago
You'd make the filament go slightly diagonally across the field of view of the camera, and then you'd have thousands of part-filled pixels. As long as your material is consistent (no bubbles, shiny spots, etc.), You should be able to build a very accurate sensor this way.
elcritch 6y ago
For high accuracy, the brightness is really more the limiting factor, as most of the edge finding/binarization algorithms use a intensity factor for cutoff. I used camera measurement for small pieces of tissue samples in biomechanical measurement (~1mm x 5mm). We had a small window in our lab, and cloudy days would distort measurements. I solved it mostly by going to a SLDR camera from a handheld and a backdrop with a type of luminance chart. Much more accurate than calipers for soft squishy (and wet) samples. See [1] Figure 2E (pg 22), you can average out small variations pretty readily. 1: https://pdf.sciencedirectassets.com/274145/1-s2.0-S1751616116X00112/1-s2.0-S1751616116304477/Jaremy_J_Creechley_Creep_Fracture_2016.pdf https://pdf.sciencedirectassets.com/274145/1-s2.0-S175161611... Though your idea of a light source and adc could work well if you put it in a darkened enclosure. It’d probably require a bit more hardware design or tuning but the software / microcontroller side would b simpler. A RPi PiCam with a macro lens would work well too, but the reverse with less hardware tweaking and more software.
econcon 6y ago
I found this video https://youtu.be/kpsN78mQ6YY https://youtu.be/kpsN78mQ6YY They use a laser pointer to measure width of a hair.