<nmz787>
anyone here ever come across code to process video data of a white light interferometer?
<nmz787>
I was reading a thesis last night that said it had MATLAB code, and gave a decent overview of how they constructed it using microscope parts, but they didn't have a URL link for the files
<pie_>
nmz787: email the authors? :/
<nmz787>
yeah I could try that
<nmz787>
there aren't any white light interferometers on ebay even, nor 'interferometer microscopes'
<pie_>
whatcha up to?
<nmz787>
working on laser-write lithography... would like to be able to convert microfluidic 3D models to g-code, and integrate the laser etcher with a spin-coater to add subsequent layers... but would need a thickness monitor for the layer addition step
<nmz787>
I think
<nmz787>
unless I calibrate and time things
<nmz787>
i might also be able to use something with a laser and reflection to detect layer thickness
<nmz787>
(a non-exposing laser color)
<pie_>
g-code?
<nmz787>
and I also realize that different laser systems will have different working distances (the ebay mini laser etcher i have now is about 2" working distance, while a blu-ray laser from a blu-ray writer is a few millimeters)
<nmz787>
for driving stepper motors of the XY gantry
<pie_>
so do you have the actual interferometer hardware yet?
<pie_>
just wondering
<Sync>
nmz787: spin coating is extremely reliable
<nmz787>
I have all the stuff to make a simple one
<pie_>
idk anything about white-light interferometry but i have a clue about monochrome interferometry
<nmz787>
i just have some beamsplitters and first-surface mirrors and some lenses (for magnifying or projecting the output onto a wall)
<pie_>
thats only for relative displacement though, given that white light is made of multiple frequencies im guessing that gives a better idea as to the displacement o#f a surface?
<nmz787>
white light has some more complex processing, but it has advantages too.. apparently the short coherence versus lasers makes it such that surfaces in-focus show colored fringe lines... making auto-focusing for something like the layers of photoresist supposedly easiers
<nmz787>
yeah something like that
<Sync>
usually if you want to measure resist thicknesses you use confocal microscopy
<nmz787>
I feel like it is something like a beat frequency of the colors in the light input
<nmz787>
Sync: it seems the difference is that white-light interferometry does better on steep slopes, but has a bit less lateral resolution
<Sync>
it is not really important
<Sync>
we just use confocal microscopy and it works fine
<nmz787>
yeah I would probably not be testing in areas of etching
<nmz787>
the next question is the interferometer easier to build than confocal
<nmz787>
there is one design that uses a beamsplitter and two normal objectives
<nmz787>
(which they say could be seen as a waste of a good objective)
<nmz787>
so I guess it would depend on if confocal lenses are cheaper than 2 normal
<nmz787>
or if they use 'normal' with some other addition components (I seem to see something about a pinhole)
<nmz787>
so the further apart the surfaces are, the less signal gets to the detector?
<nmz787>
so seems like you should be able to detect subsequent layers too?
<Sync>
uh
<Sync>
well
<Sync>
I dunno why you would use multiple layers
<pie_>
optics is expensive as fuck :X
<pie_>
i find interferometry pretty cool for some reason, i want to do some more reading about it when i have the time
<nmz787>
Sync: I was thinking I might be able to use SU-8 directly for the device, then I could spin-coat, pattern, skip development and repeat layering/patterning... after a few layers, develop all at once
<nmz787>
not sure it would work
<nmz787>
if not, then I'd take the single layers and make them serially and stack them