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metal fatigue
06/06/2014 at 18:41 • 0 commentsIt's killing my flexible wires again and again. This one lasted for only about 5 minutes.
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on the way to a new sensor
06/06/2014 at 00:09 • 0 commentsSome build progress. The alignment stage. The semitransparent mirror was taken from a CDROM optical head. Its thickness is about 2 mm, which I find being way too thick for the purpose, but I have not found anything else yet.
And I've found a good source of tiny optoendstops - a digital camera. There are 4 in there. Brilliant!
This version of the sensor looks too large to be embedded, so I'm making it for the mere purpose of getting a working sensor. Once I get it, I'll build another one as small as I possibly can.
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on the way to new sensor
06/01/2014 at 23:15 • 0 commentsInside a CDROM I've found a piece that can potentially serve as the sensor, except it's very unlikely I will ever get direct access to this photodiode.
Update: there is some sort of a part number printed on one of the dice. It says "SONY A2527". Couldn't find any info unfortunately.
Anyway, aiming a laser into the eye doesn't look like a good idea.
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some thoughts
05/31/2014 at 22:49 • 0 commentsI think i'm not going to throw this v0.0 sensor away right now. I'll make some shielding, put a heavy-duty high-pass filter and see if it helps.
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the first sensor is a FAIL
05/31/2014 at 22:00 • 0 comments* First point is that it is too sensitive to visible light around. But even if I switch the light off...
* second is that it is only sensitive to a huge model of the eye - a big lens and a palm over it. I do get a reliable peak out of that system, but it is a small change in a quite big background signal. As for the eye behind the eyepiece - simply nothing.
So, back to thinking.
Update:
channel1 (yellow) - speaker drive voltage, which is more-or-less proportional to motion speed (half of the whole period is displayed).
channel2 (cyan) - signal from phototransistor, AC coupled. There should be a peak somewhere around the center, but there is no.
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the sensor v0.0
05/31/2014 at 21:07 • 0 commentsso, this is the first attempt on making a sensor. I destroyed an opto-endstop, and then put the LED and the phototransistor in close proximity separated by a piece of aluminium. Now I'm going to do some tests - I have glued it to a speaker, which will serve as a vibrating platform for now.
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building the sensor
05/30/2014 at 23:28 • 0 commentssome fine work is being done under the microscope at night.
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building the sensor
05/29/2014 at 22:40 • 0 commentsWhat I need are the IR LED and sensor (preferably photodiode, but a phototransistor may work). Both should be tiny, and I have to place them really close to each other.
After a bit of research into fiber optics and some other stuff, optical endstops came to mind. I picked the tiniest one and now trying to figure out the best way to put them close to each other. A bit of dremeling, and I have the edge right next to the LED crystal.
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decision: config.1
05/28/2014 at 23:20 • 0 commentsAnd then came Mr. Murphy and said: your lens' surface acts as a mirror that has its focal point near the image plane. That rules out configuration 2 and any other where the sensor is placed on the optical axis.
That doesn't affect anything if the sensor is off-axis. So, the choice is made: the sensor inside the eyepiece. Maybe it's time to start building stuff.
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playing around with the red-eye effect
05/28/2014 at 22:59 • 0 commentsit's a bit hard to look into my own eyes with my own eyes, so I looked with a camera. And why not upload a resulting video to youtube? That's exactly what I've done, enjoy!