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Fabrics! (part 1)

A project log for LadyBug BEEFY: 3D printer motorized microscope

Got printer? Connect to the motors with a Pi, plonk in a cheap scope, and do 2D and 3D scans!

WayneWayne 01/22/2020 at 23:150 Comments

I saw someone on facebook talk about scanning textures of things like fabrics, for overlaying onto 3D models. So I found something nice and cute from our school's wearable electronics stockpile:

They key innovation here being the use of binder clips to keep the fabric stretched out and as flat as possible. I've said it before and I'll say it again: Autofocus post-process is possible, but it's easiest to just make it all in-focus to begin with.

The focus on the scope is adjustable almost from infinity to less than a millimeter. The closer you get, the higher the magnification. This does not strictly mean that the resolution increases; that is limited entirely by your illumination wavelength/method and your lens's numerical aperture. But dinolite is relatively respected and they prevent the dial from turning past the point where you're getting fake magnification.

I did three scans: far away (~5 cm), medium (1cm), and close (less than a milimeter). The scan length and difficulty in keeping things in focus are directly related to the magnification, so far away = super easy, medium = probably can keep it all in focus, large = you'll get bad patches unless you do multiple Z heights.

For comparison, the lowest magnification took 50 pics to see the whole fabric, the medium took 500, and the highest would take about 5000, if you were only doing one Z height. I'm doing three, adjusted about a half millimeter apart each. There's also the danger that the fabric will drift for whatever reason (there are many) in between each change in Z height (the raster pattern happens first) and you'll be unable to do any kind of point-by-point comparison for focus afterwards, but I think even in the worst case most of the image will be roughly in focus even at one Z height.

Anyway, I'm not going to post the full images now (mostly because the highest res one is still running), but the first two look good. Here's one image of the high res, though, to show you what that fabric looks like up close:

Comparison, here's a "medium" one, which is about the same resolution as my scan of the front and back of the 50:

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