Mirror Camera project

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Re: Mirror Camera project

Postby Harry Dalek » Sat Aug 09, 2014 12:21 am

gary wrote:This is just my opinion Harry but I think you should persevere with this arrangement if only for the "hell of it' - in principle it should be able to produce a reasonable picture and who cares if it isn't exactly to spec? I mean there are people on this forum who are (shhhhh) experimenting with entirely "electronic" systems - yes sacrilege I know, but if it makes them happy... and, more importantly, keeps them quiet... ;-)


Oh yes there is something about a mechanical way that perhaps makes it a little harder and combines them both ,i just wanted to try the rocking mirror idea to see if it would work i expected problems on that side of things.
The optics would of been easier if the polygon was a wider mirror but would be boring if all this was easy .

If you put 6.25 Hz into your "vibrating" mirror then you should end up with 12.5 frames per second if my imagination serves me right (and heaven knows I am no Einstein or Tesla when it comes to "thought experiments").


I have to send the results from tonights test in the next post as its on the lap top i recorded them on as wav files but results were it worked at 12 hz and not at 6 hz ! i don't understand...i did some recordings as your frequency testing would be better than mine .

I tell you what - if you continue your experiments with this I will write some software to reverse every second frame and display it correctly, hows that?


That would be good if still needed :wink: but tonights test may well interest you i am double checking with you what you think .

and yes you could up the line rate to 800 Hz and go 25 fps - why not? But can your motor/polygon do 8000 RPM???


May be if i do a direct drive the pulley system at the moment looks around 3 to 1 off hand have to really check that .

BTW, what do you mean by resonance? I assume you are talking about a galvanometer type of set up?


I think it is just the oscillating magnetic field rocking the thin flat metal rod at the best point more than likely be a different position with out the large mirror but it works what ever you call it .

I am not sure what they do in the 625 line oscillating mirror systems (I have never really been convinced they are real) but, in a CRT television system they actually require a finite fly-back period (can you image such inadequacy? tch tch) and I suppose it is possible for a very well designed galvanometer to replicate that, I am not sure.
[/quote]

I have seen 2 and had me wondering ! any case all that is why beyond what i could do .

I will upload the results of tonights test next post .
Attachments
IMG_8924.JPG
12 hz test single image of the led
IMG_8924.JPG (306 KiB) Viewed 5884 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mirror Camera project

Postby Harry Dalek » Sat Aug 09, 2014 12:34 am

OK here are the wav files 1 at 6Hz and 2 at 12Hz the second i adjusted my free running 555 timer to slow the drift as best i could it must be close to 12.5 Hz ?

Now what i don't understand is how is this working a single led at 12 hz ? it looks right but i feel something is up mabe it just spreads the lines apart more ? thats all i can come up with.

I would be interested to find out for sure !
Attachments
6hz.wav
(823.17 KiB) Downloaded 289 times
12hz.wav
(1.09 MiB) Downloaded 297 times
12hz,,,,2.wav
best adjustment
(883.64 KiB) Downloaded 273 times
12hz test.gif
12hz test.gif (6.74 MiB) Viewed 5883 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mirror Camera project

Postby Harry Dalek » Thu Aug 14, 2014 12:38 pm

i have not had much time of late,but have been studying Allan Shorts designs in the mean time .
What has me wondering is the frame movement mirror as in the screen grab , some times he just used a light sensor frame movement apart from the mirror but any way .
I can see the cam it would be doing a mechanical saw tooth and near instantaneous fly back of the mirror but this would mean the mirror would still take the same time a rocking mirror magnetically driven swinging back to the start position if they are driven at the same frequency ?..i am sure hes system worked well but with a little more fiction and noise .
Perhaps he used a spring that might speed the fly back up don't know hard to tell with drawings,i did find that when a mirror on a relay if driven to hard by hitting the relay case caused unwanted vibrations on the mirror.
I think he did say it was better on a slow scan idea than NBTV.
Another reason to have a look at Allans work i have been having a rethink about the optics on mine as is its seeing angle is very narrow ,it does not help when line mirror is narrow which is more than likely the cause .
I might have to replace the polygon mirror as is with a wider mirror drum,but i will try every option ,Allan has explained the optics well on hes cameras so thats a big help. i don't intend to give up .
Attachments
Screen 00005.jpg
allan short one of hes camera designs
Screen 00005.jpg (9.33 KiB) Viewed 5852 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mirror Camera project

Postby gary » Thu Aug 14, 2014 3:33 pm

Harry Dalek wrote:OK here are the wav files 1 at 6Hz and 2 at 12Hz the second i adjusted my free running 555 timer to slow the drift as best i could it must be close to 12.5 Hz ?


The trouble is Harry is that even "*very* close" is not good enough to to stop drift - it has to be locked to the polygon somehow - perhaps by a divider chain or by PLL.

Harry Dalek wrote:Now what i don't understand is how is this working a single led at 12 hz ?


It depends on what the rate relationship is between the polygon and the mirror - what is the rpm of the polygon? Is the sync coming off the polygon or being generated electronically?
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Re: Mirror Camera project

Postby Harry Dalek » Thu Aug 14, 2014 8:00 pm

Hi Gary

The trouble is Harry is that even "*very* close" is not good enough to to stop drift - it has to be locked to the polygon somehow - perhaps by a divider chain or by PLL.

Yes it was just a quick test with one of the timers i used for the vibrating mirror experiments a while back to see if it would work ,i understand there will be drift as is ...sort of why i was a little reluctant going crystal with the 4060 ic ,i lost the 12 hz ,i have not tried your solution or got around to thinking about it yet still rethinking the optics side of things.

It depends on what the rate relationship is between the polygon and the mirror - what is the rpm of the polygon? Is the sync coming off the polygon or being generated electronically?


Sync is mechanically generated off the 6 sides of the polygon i suppose with an opto switch ,the vibrating mirror was a free running 12hz 555 to a power trany then to the relay just used as an electromagnet vibrating a thin steel plate with a mirror again just for testing .
On the RPM measurement i don't really have a way to do it ,it should be correct or my line frequency would be off ?

I am sort of aiming for an image drifting or not a bit above seeing an led so i want to go to that step.... best i got was very limited viewing of a few lines and very blurry so i know my optics as was ,was not good enough and so back to the drawing board !

Having a look at most of Allan's camera designs I am giving it another go looking at copying the lens idea closer to the mirror drum ,thinking of using a fiber optic strand instead of the frame mirror ...
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mirror Camera project

Postby gary » Thu Aug 14, 2014 8:53 pm

No the line sync pulse separation was quite good such that I thought it may have been artificially generated.

In that case I can't understand why you are getting 2 images at 6 Hz because at 12Hz you are effectively at twice the frame rate - maybe my logic is wrong.

Harry, getting back to the width of the polygon, if anything it is too wide and you may need a mask I think.

Your arrangement, if I am not greatly mistaken, is similar in operation to Bairds 240 line system where the disk, instead of having a spiral, just had it's apertures at the same radius and the frame, in the form of an intermediate film, was pulled across the disk mask to achieve the line scan. In your case the relay mirror is dragging the image across the polygon.

Have you placed a white piece of cardboard (or similar) directly in front of the polygon to ensure the image is in focus and being moved across the polygon correctly?
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Re: Mirror Camera project

Postby Harry Dalek » Fri Aug 15, 2014 1:07 am

gary wrote:No the line sync pulse separation was quite good such that I thought it may have been artificially generated.


I think once i worked out how critical the pulley tension was to speed control and cutting down vibration at the opto switch its seems a bit better than perhaps a encoder on a disk with a bit of wobble .

In that case I can't understand why you are getting 2 images at 6 Hz because at 12Hz you are effectively at twice the frame rate - maybe my logic is wrong.


It was some thing i was not expecting ,i really should of taken a sample at a few different frequencies to see .at the moment its in a remake stage the optics side almost there .

I tried btw to do a direct drive for the polygon but i couldn't get of some vibration with the motor on top of the polygon so that was a no goer back it went .

Harry, getting back to the width of the polygon, if anything it is too wide and you may need a mask I think.


I will try a mask i read Allan shorts polygons were to wide he was getting blurring he masked off the edges and it seemed to fix it making the mirrors smaller that way worked .

Your arrangement, if I am not greatly mistaken, is similar in operation to Bairds 240 line system where the disk, instead of having a spiral, just had it's apertures at the same radius and the frame, in the form of an intermediate film, was pulled across the disk mask to achieve the line scan. In your case the relay mirror is dragging the image across the polygon.


Thats interesting my main reason for trying that was mirror size differences ,its changed now for a different go , its more similar to Mr shorts cameras so lens to line polygon mirror then off the polygon back out the lens to the frame vibrator which will have a fiber optic pickup instead of a mirror then feed that fiber to the light sensor worth a go to see .

Have you placed a white piece of cardboard (or similar) directly in front of the polygon to ensure the image is in focus and being moved across the polygon correctly?


I could see reflection off white object and darker differences but it was all to blurry and to narrow only a small section of the raster to tell ,i will take that advice in when i do a run on the new version .
Attachments
IMG_8926.JPG
IMG_8926.JPG (350.26 KiB) Viewed 5843 times
IMG_8929.JPG
IMG_8929.JPG (395.5 KiB) Viewed 5843 times
IMG_8932.JPG
IMG_8932.JPG (329.67 KiB) Viewed 5843 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mirror Camera project

Postby Harry Dalek » Fri Aug 15, 2014 9:00 pm

Hooked up the fiber optic strand today to see what it could see !
I did a few tests polygon sweep, vibrating test, reflecting off white paper ,last which is harder to see i also looked into while doing these tests hooking the end of the fiber strand to the head amps sensor that seems to work .
It does give me the option to use the more sensitive solar cell or dome sensor ,i just recall my head amp circuit worked best with these .
I will Take on Gary's advice on masking around the mirror I tried painting black unwanted reflecting parts on the polygon mirror which i was thinking might help but have not used that in a test run yet,Allan shorts mirror drum had a rotating mask due to hes drum design but i just need a slot but might be an idea to encase it with a light slot .
BTW you might not see it well i just held the end of the fiber strand in place around the back of the electro magnetic just for filming .

edit ....just finished the mask idea
Attachments
optic fiber test.gif
Close light test
optic fiber test.gif (5.96 MiB) Viewed 5827 times
fiber optic test light distance test.gif
moving the light a little further away
fiber optic test light distance test.gif (5.78 MiB) Viewed 5827 times
vibrating view.gif
magnetically moving the fiber
vibrating view.gif (2.84 MiB) Viewed 5827 times
IMG_8947.JPG
mask idea
IMG_8947.JPG (310.54 KiB) Viewed 5826 times
IMG_8948.JPG
IMG_8948.JPG (334.74 KiB) Viewed 5826 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Mirror Camera project

Postby Harry Dalek » Thu Aug 28, 2014 7:49 pm

Well i have still been working on my project looking into what problems i still have and trying different ideas .
On the fiber optic idea in my last post i found i needed to bundle a few of the fibers together before i got enough light for the light sensor to give results.
I found this to be to thick for what is needed so left that idea behind .
I next tried just a direct approach with directly trying to vibrated the light sensor cabling it was a no no so just tried vibrating it on the circuit ,i found this a little to cumbersome but it did give the best results on reflected light ,i could see lines in my test card but still blurry and to large ,i had no way to adjust the light sensor position trying this so could not focus.
Alan short did mention the light sensor position is critical he did also remove the lens off hes light sensor and re polish it ,i am not brave enough to try that yet.
So looking into the what works so far with a few changes again.
The line mirror is first light mirror then i have gone back to a frame mirror magnetically moved then the light sensor with a different lens which i want adjustable since i think the lens on the light sensor is magnified the sensor size i think i need to drop the size of this with this smaller lens ,it works visually just have to see what happens while testing.
I looked into how many reflecting areas were above and below the polygon mirror and painted every thing black now so should think this will help .
I am leaving the positioning of the light sensor to a working test ,i haven't taken a photo of the newer look i could place it above the polygon mirror looking down to the frame mirror or to the side ,i will post some pictures up with the next run .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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