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<jesseg>
Noxz, I don't know anything about these laser photoplotters, except I'm in the planning stages of building a raster scanning laser photo plotter for myself for selectively exposing PCB solder mask & silk screen using uv blue ray laser and spinning mirror optics from old laser printer.
<Noxz>
I love how cheap that source given is
<Noxz>
but - at what point should I look at building one myself?
<Noxz>
should certainly get a few demos in before I invest time/energy/money into my own thing
<jesseg>
If you built a vector plotting style instead of a raster scanning style then you could have better detail in any direction
<Noxz>
I have a feeling raster may be better for me for various reasons
<jesseg>
yeah it allows a much more complex scene to be printed much faster
<Noxz>
well, curves
<Noxz>
curves I feel would be slower/not as good via vector based
<jesseg>
but then you end up with aliasing issues on diagonal features, and laser turnon-turnoff delay inaccuracies in the high frequency axis
<Noxz>
too much moving around versus just bruting it
<jesseg>
I suspect they overscan a bit -- each next scan line probably overlaps half the beam spot diameter from the last one
<Noxz>
so, the tradeoff is either laser on-off, or the stepper/stage advance
<jesseg>
exactly
<Noxz>
you can time based on acceleration/velocity and such
<Noxz>
versus trying to follow lines as a bit more of a hassle with the fluidicity of the stages
<Noxz>
ie, more pixelated then
<Noxz>
I'd like to look into the [what is the term called.. photoreducing?] the mask to smaller output
<Noxz>
I undertsand some of the basic optics, but havent looked at what is involved
<Noxz>
it's "basic" optics to piece something together to beam light through a mask to a smaller output
<Noxz>
not exactly diffiuclt
<Noxz>
but, I would pay $400 for such a thing already made, honestly
<Noxz>
we're basically talking about like 2 or 3 lenses, a light source (exposure) and 2 or so Z stages
<Noxz>
for focusing
<Noxz>
almost makes sense to just use a "standard" camera lense plus a light
<Noxz>
easily interchangeable, etc
<jesseg>
oh like a photographic enlarger in reverse?
<jesseg>
actually, probably just take a photographic enlarger and use the lene backwards at the other end :P
<Noxz>
well, like any camera lens.. it takes a lrge photo (the target) and ofcuses it to the sensor
<jesseg>
yeah
<Noxz>
the idea here is that you can swap out the lense with some standard adapter thing
<Noxz>
easily
<Noxz>
industrial standards
<Noxz>
looks like 300-400 can get a decent used lens
<Noxz>
leica
<Noxz>
the focusing and calibration sortathing is what will take osme initial time, but you know, once you have it setup, then it should be set
<Noxz>
plus i have piezo stages, top fine tune, then what, just set screws to keep things in place
<Noxz>
though, I dont have piezo rotational stages
<Noxz>
again, I dont know much about optics
<Noxz>
just some initial thoughts - and the idea of if you ahve the same size silicon wafer and masks, then nothing really needs alteration beyond an initial calibration
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<Noxz>
I know of only one person who looked into optics enough to ask questions to, but I know they are always busy
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<Noxz>
looks like many are just using a microscope in reverse.. I guess it all depends on how big your mask is, to how small you want the end result
<Noxz>
the advantage of going for a high resolution mask vs the DLP method is - well, the resolution, and more of a pre-production run, versus rapid prototyping
<Noxz>
on second thought, due to experiments, the DLP method may prove satisfactory for initial testing
<Noxz>
unless more curves and smaller stuffs is needed
<jesseg>
I wonder how a regular camera lens would do at reducing.
<Noxz>
that's kinda what I was saying to use
<Noxz>
a macro lens or similar
<jesseg>
If you think about it, if you take a modern digital camera even a cheap one, it can focus down to detail as fine as its pixels which are bloody small
<Noxz>
plus a collimator for the light source? if needed
<jesseg>
the pixels on its CCD/CMOS image sensors
<Noxz>
well.. the lens it comes with helps, too
<Noxz>
you can have crummy/low grade optics
<Noxz>
but, are you just doing B/W ?
<Noxz>
ie - does it matter much for our sue case
<jesseg>
the optics in modern cameras - even every day point and shoot digital cameras - are often extremely good
<Noxz>
but there is a reason that lenses are offered
<Noxz>
and - that's what we would want
<jesseg>
yeah they may be more linear in the UV region
<jesseg>
Are you thinking of reducing it to smaller film, or reducing it directly onto silicon?
<Noxz>
some PR are active in other regions of the spectrum
<Noxz>
reduce it to silicon
<Noxz>
no reason to go from mask to a smaller mask
<jesseg>
but uv allows you smaller features
<Noxz>
ah, right, more vertical walls, right?
<jesseg>
yeah agreed on no need for a smaller mask
<Noxz>
SU-8 and PMMA are the two PRs I am more familiar with
<jesseg>
more vertical walls means you can have more walls in an inch :D
<Noxz>
well, and the light that comes down vertically will give you the image you want
<Noxz>
the polymer itself has a certain resolution, too
<jesseg>
yeah
<Noxz>
I'd like to think this issue/problem has been solved, DIY wise, many times over
<Noxz>
how much is a 4k dlp projector?
<Noxz>
seems to start around 500, whereas a simple PoC of liek 1900x1200 res is about 150-ish
<Noxz>
DLP + reducing lens is what is needed
<Noxz>
and if that works, then yeah, higher res pre-production tests with a mask
<Noxz>
what I need to do is stick with a plan
<Noxz>
I think what I dont want is to get stuck buying chep stuff that gets replaced with higher quality/cost stuff later on - like, why not just get the good stuff now
<Noxz>
ie - what do I gain from being able to do fast prototyping if I cant do high res? and for more production need to do the commercial masks
<Noxz>
it seems like a good lens is still on the list
<SpeedEvil>
I wonder how the nominal lens would improve with single wavelength illumination
<Noxz>
one issue I can see with the polymer masks is they arent rigid (the source states they can do glass/etc) so there may be a frame with tensioners needed ot be built (thinking ahead)
<Noxz>
so, just noting some things on (re-)learning lens optics and acronyms.. the apertures we would be looking for is lower numbers, like f/1.4 and below, to allow the most light through
<Noxz>
I feel stupid learning some of these basics (again, for the 10th time, likely)
<Noxz>
meh, needs to be done
<jesseg>
yeah
<jesseg>
however lower f lenses also have a much thinner zone of focus
<jesseg>
so focusing exactly becomes more critical
<SpeedEvil>
Higher F number is generally less abberant
<SpeedEvil>
neglecting lots
<jesseg>
so if you have a higher f stop it's easier to get a crisper image for reasons of focus and as SpeedEvil says, aberration and other anomalies
<Noxz>
I dont know why you wouldnt be focused though.. you are taking a flat projected image/masked light, and beaming it onto a tiny silicon wafer
<Noxz>
and seems like it only needs to be done once per PR thickness+silicon wafer thickness
<Noxz>
I may not be following too much on how it fully works, but makes sense if you want to transmit more light, which we want, then lower aperture is desired
<jesseg>
well, the distances on the two sides of the lenses are inherently related in a kind of non-linear(?) inverse relationship
<Noxz>
also, would an adjustable focal length be desireable w/ masks? likely so
<Noxz>
initially, until you figure out what you can get out of that 8k dpi mask
<jesseg>
but the wider the aperture is the more angles and distances the light will be ariving at from
<Noxz>
we have a 20x loupe for examinig our oiling on pallet stones.. makes me dizzy when I put it on
<Noxz>
the 10x is usually plenty
<Noxz>
I wea the 6 thorughout the day, but I wanna switch to the 4
<Noxz>
I think I need to see more examples of aperture in use, but also relate it to the fact that we are generating all of the light we want ourselves, and nothing stray is getting in
<jesseg>
I have just what you need.
<jesseg>
It's a 35mm film camera.
<jesseg>
LOL you can have it for shipping :P
<Noxz>
heh, I'm looking into specific numbers and whatnot
<jesseg>
it'll reduce any size of scenery you have down to the size of a 35mm film
<jesseg>
which is just the right size for your home made cmos integrated circuit :D
<Noxz>
heh, many of the super fast apertures are radioactive w/ thorium oxide
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<Noxz>
oh, also, for [self] reference the buckling mechanism I want to design (replace) had an actuation force of 450grams on a scale (essentially 1lb), so something like 4.4 Newtons .. which gives some insight into the strain gauge setup
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<jesseg>
hey speaking of micro-actuators.. Regular piezo beeper speaker disks - like in smoke alarms or electronic watches or you name it -- they make pretty neat actuators. You can usually get away with a hundred volts or two and get a mm or two of deflection.
<jesseg>
they go concave for positive voltage and convex for negative voltage
<jesseg>
I'm sure they aren't exactly linear but they are readily available and cheap :P
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<SpeedEvil>
jesseg: how many cycles have you tested/
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<jesseg>
SpeedEvil, oh maybe a hundred at 8kv at which point it would arc over on the disk LOL.
<jesseg>
it was years ago and I was just playing with it
<jesseg>
I never did anything serious with it
<jesseg>
obviously at lower voltages they can handle millions of cycles because they run at a Khz or two
<jesseg>
and obviously they are designed to have a strong resonant frequency which is how they can be so bloody loud in a smoke alarm running off only 9v
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<SpeedEvil>
:)
<jesseg>
I bet the piezo elements out of bbq sparker lighter buttons could also be used and they are even rated at high voltage :P
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<Noxz>
jesseg, buzzer piezos were used for a cheap STM iirc
<Noxz>
that is a good source though, for what is possible with how little
<Noxz>
so, I was looking up mini steppers before hitting the sack last night, and appears most of them (such as for cdroms etc) are 20 steps per turn, which I find crazy when my large NEMA34 steppers are 200 steps per turn - curious if anyone has a source of high(er) steps for small ones
<Noxz>
I would likely be looking at using a 100 TPI adjustment screw as the lead screw
<Noxz>
and a max of 2in travel
<Noxz>
with a force of, I dont know, up to 1kg?
<Noxz>
20 stepss w/ 100 TPI is basically 1.25um/step
<Noxz>
if my math was correct
<Noxz>
this is for an (automated) force calculator of buckling mechanisms.. initially testing some 0.1mm width 316 flat wire
<Noxz>
plenty packs of mini steppers from ebay/amazon - but getting somethign better than 20s/rev would be nice
<Noxz>
I was thinking about some other form of less friction position tracking (linear encoder) but good to know these are easy to hack, and @ ~$10 it's hard ot beat
<Noxz>
but, a proper DRO/linear encoder (glass over plastic film? the photomask place stated they can make stuff) would be much btter, especially if your movements are very small
<Noxz>
for overcoming the stiction forces anywhere
<Noxz>
during the hike with my dog, I thought about replacing the (stainless ?) steel caliper body with PTFE/Delrin to help this
<Noxz>
100tpi small lead screw + 200step/rev = 50 millionths resolution
<Noxz>
so, caliper integration is obviously not anywhere close to reading such a thing, but digital micrometers could potentially.. I wonder if they have a similar interface hack
<Noxz>
~$40 for a cheap knockoff one on amazon, may be worth checking into
<Noxz>
I wonder how the digi micrometers work in comparison to the calipers, havent looked into it
<Noxz>
the difference of $40 for a cheap micrometer vs $10 for a caliper may be worth it in the end..
<Noxz>
1" of travel may or may not be enough for people though
<Noxz>
my piezos do that, but a "step" may or may not actually happen.. also, nto entirely sure how you would go about activating the micrometer or using it compared to calipers which due to the sliding nature makes it easy enough