Mini version of Scophony - its do-able

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Re: Mini version of Scophony - its do-able

Postby Gregory » Fri Mar 11, 2016 7:10 am

Harry Dalek wrote:Hi Gregory

Good looking mirror will do the job for sure .

Just have to get the balance correct on the motor which it needs to be or your raster will sway every 12 lines .

The frame mirror is much easier you can make that yourself even just to see it work till something better comes along .

The mirror looks like it has angled mirror on the top as well ? this is good for the frame mirror if you did get another.

You will have it all going in no time,got the motor going easypeasy 8)

Hi Harry,

The PWM driver I got from ebay for $5 inc shipping and it will spin my mirror to around 14000 RPM the link is
http://www.ebay.com/itm/5V-12V-DC-Brush ... 2054147531?

I made a mistake in earlier posts on the mirror as it is 15 sides and not 12 sides so motor speeds required would be

32 lines 12.5 frames/sec = 1600 RPM
60 lines 20 frames/sec = 4800 RPM
120 lines 25 frames/sec = 12000 RPM

mirrormount.jpg
mirrormount.jpg (64.84 KiB) Viewed 7106 times

Just made the flange and mounted the mirror to the HDD motor. To the eye the mirror seems to runs true with no wobble or eccentricity and the HDD motor now spins to a maximum of around 14000 RPM with 7.5v DC

Due to the heavy mirror The PWM driver makes several attempts before the motor starts spinning. Unfortunately the PWM driver uses surface mount components and the ICs are not marked, so there is no possibility of changing the start frequency circuit. Still it only cost $5 from ebay so its good for initial tests.

linescan2.jpg
linescan2.jpg (44.64 KiB) Viewed 7106 times

I have also temporarily attached a laser pointer to see the line scan as above
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Re: Mini version of Scophony - its do-able

Postby Harry Dalek » Fri Mar 11, 2016 11:46 am

Gregory wrote:Hi Harry,

The PWM driver I got from ebay for $5 inc shipping and it will spin my mirror to around 14000 RPM the link is
http://www.ebay.com/itm/5V-12V-DC-Brush ... 2054147531?


Thats pretty good more than likely a bit more for me ,i will look into this when i get another mastercard do some on line shopping .

I made a mistake in earlier posts on the mirror as it is 15 sides and not 12 sides so motor speeds required would be

32 lines 12.5 frames/sec = 1600 RPM
60 lines 20 frames/sec = 4800 RPM
120 lines 25 frames/sec = 12000 RPM


Well thats even better ! i still have a few 4,5 and 6 sided ones but wouldn't mind a 15 for sure .

mirrormount.jpg

Just made the flange and mounted the mirror to the HDD motor. To the eye the mirror seems to runs true with no wobble or eccentricity and the HDD motor now spins to a maximum of around 14000 RPM with 7.5v DC



This is good no wobble you are doing well !

Due to the heavy mirror The PWM driver makes several attempts before the motor starts spinning. Unfortunately the PWM driver uses surface mount components and the ICs are not marked, so there is no possibility of changing the start frequency circuit. Still it only cost $5 from ebay so its good for initial tests.



May be a Dc motor in a pulley system as a starter motor might fix that problem . but yes for 5 dollars well worth it even if you have to hand spin it to get it going.
I have also temporarily attached a laser pointer to see the line scan as above



Are all the lines over lapping or there will be shaking in the raster image again even so it wouldn't stop it working .

What are your plans as to the screen ,you could paint a glass picture frame glass pane and enclose it in a case and view from the front .

when you get a laser for it get one where you can defocus the beam .

All looking good ! :wink:
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: Mini version of Scophony - its do-able

Postby Gregory » Tue Mar 15, 2016 6:38 am

Next - phase 2 The frame scan mirror, motor and driver.

As a suitable polygon mirror for the frame scan is not available ready at a reasonable cost, I am going to have a go at making the polygon mirror. To avoid any additional optics, and keep thing simple, an 8 sided mirror would be the minimum no of faces to use without too much distortion in line spacing, For a line scan spacing of 1 mm in the middle of the screen, an 8 sided mirror with 45 degree deflection would give a calculated line spacing at the top and bottom of 15% more (i.e. 1.15 mm) which probably would not be noticeable.

I have a size 17 stepper motor handy, which will be used for rotating the mirror, together with the stepper driver bought.

Harry, the final screen will probably be a flat ground glass or acrylic screen, and to have an image size of 8 cm wide x 6 cm high. This would have 1 mm line spacing for 60 lines, and for 32 lines as you suggested Harry, the best option may be to de-focus the beam if possible, to remove the gaps.
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Re: Mini version of Scophony - its do-able

Postby Harry Dalek » Tue Mar 15, 2016 6:14 pm

Gregory wrote:Next - phase 2 The frame scan mirror, motor and driver.

As a suitable polygon mirror for the frame scan is not available ready at a reasonable cost, I am going to have a go at making the polygon mirror. To avoid any additional optics, and keep thing simple, an 8 sided mirror would be the minimum no of faces to use without too much distortion in line spacing, For a line scan spacing of 1 mm in the middle of the screen, an 8 sided mirror with 45 degree deflection would give a calculated line spacing at the top and bottom of 15% more (i.e. 1.15 mm) which probably would not be noticeable.

I have a size 17 stepper motor handy, which will be used for rotating the mirror, together with the stepper driver bought.

Harry, the final screen will probably be a flat ground glass or acrylic screen, and to have an image size of 8 cm wide x 6 cm high. This would have 1 mm line spacing for 60 lines, and for 32 lines as you suggested Harry, the best option may be to de-focus the beam if possible, to remove the gaps.


Hi Gregory
If you are making the frame mirror the best idea is to use the thin plastic mirrors you can cut out with a stanley knife the ones with contact backing ..if you use glue it will throw the mirror angle off ,the mirror has to be pretty much flat contact with the shape you are using for the mirrors ....well thats i have found trying glue..an idea that does work also is to make the mirror a touch larger and place flat on the shape and glue the over hanging ends to the top and bottom of the shape if you can't find the ones with a backing .
So you really need an accurate 8 sided shape now ,i just went 4 sided duplo or lego blocks are good and abundant in my house,i used a balsa wood block in the octagon :wink:
Yes when you get the laser get one where you can adjust the focus lens.
Your stepper is fine ,sounds like your ready to mount it all.
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: Mini version of Scophony - its do-able

Postby Gregory » Sat Mar 19, 2016 11:27 pm

The polygon frame scan mirror finally made. The parts were cut on a CNC router from 13 mm acetal sheet for the 2 octagon bases and 3 mm acrylic mirror for the 8 faces. In order to allow a small amount of adjustment, all the faces are held with M4 screws, with O rings on the underside. The threads in the base are tight, so the bolts wont undo, once set.

I tried spinning the frame mirror in a battery drill and it seems to run true, but I think the screws will need changing to countersunk screws as it looks a bit clumsy.

frame mirror parts.jpg
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Frame mirror.jpg
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Re: Mini version of Scophony - its do-able

Postby Harry Dalek » Sun Mar 20, 2016 1:09 am

Keep the screws its got a steam punk look to it i like it :wink:
Very neat work are you going to get some bearings for it pulley system to drive it ?
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: Mini version of Scophony - its do-able

Postby Gregory » Sun Mar 20, 2016 5:37 am

Harry Dalek wrote:Keep the screws its got a steam punk look to it i like it :wink:
Very neat work are you going to get some bearings for it pulley system to drive it ?


Hi Harry,
OK we will keep the punk look for the moment. I intend to mount the mirror with 2 bearings on either side and then connect the motor directly with a coupling of some type.

Have to now get everything together on to a base with the screen. Managed to also get hold of self adhesive semi-translucent
material from a friend, which may be suitable for the screen.

Unfortunately work only leaves me Saturday for this project.
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Re: Mini version of Scophony - its do-able

Postby Harry Dalek » Sun Mar 20, 2016 8:28 pm

Gregory wrote:
Harry Dalek wrote:Keep the screws its got a steam punk look to it i like it :wink:
Very neat work are you going to get some bearings for it pulley system to drive it ?


Hi Harry,
OK we will keep the punk look for the moment. I intend to mount the mirror with 2 bearings on either side and then connect the motor directly with a coupling of some type.

Have to now get everything together on to a base with the screen. Managed to also get hold of self adhesive semi-translucent
material from a friend, which may be suitable for the screen.

Unfortunately work only leaves me Saturday for this project.


What looks right at the projected back screen will be reversed from the front of a screen when you come to that .
Almost there you will have a multi system monitor sounds like it could do 120 line Garys software does that so you would have a video signal for it ,i would try for that also ...32 48 and 60 line should be easy peasy...have to get mine out and see as i know it had more speed might be pushing it but yours should do it.
Did you get your laser yet ?
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: Mini version of Scophony - its do-able

Postby Gregory » Sat Mar 26, 2016 9:57 pm

Harry - I have not got the laser yet, wanted to make sure everything else is OK before I splash out on one - not sure what colour would be best.

Two mistakes I made in previous posts. First the stepper motor was size 23 and not 17. and more serious the maximum deflection of the frame scan mirror for an 8 sided is 90 degrees and not 45 degrees (plus and minus 45 degrees form the centre). This will certainly produce distortion in the vertical lines with lines at the edge being much wider than in the middle - to overcome this it may be necessary to make the screen curved in the vertical direction.

Managed to make more progress this week. The frame mirror is now mounted direct to the stepper motor and I used a 10 cm M8 bolt which has a hole drilled on the head side to accept the motor spindle. To fix to this I just used epoxy metal glue.

frame mirror & motor.jpg
frame mirror & motor.jpg (51.04 KiB) Viewed 6960 times


Next came the base which has the 2 sides to hold the Frame scan mirror and motor. In order to keep the mirror stable a bearing is on the opposite side to the motor. For the screen the self adhesive translucent material I got was useless as it did not diffuse well enough. At the end the best results I got using tracing paper attached to a clear acrylic front panel.

assembly front view.jpg
assembly front view.jpg (49.41 KiB) Viewed 6960 times

assembly rear view.jpg
assembly rear view.jpg (59.83 KiB) Viewed 6960 times


The photo shows the line scan mirror roughly in the position it should be, but has not been bolted down yet.

The next phase will now be to mount a couple of small mirrors for deflecting the laser beam and mounting the line scan mirror and motor. After this hopefully I can spin motors to get some sort of raster.
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Re: Mini version of Scophony - its do-able

Postby Harry Dalek » Wed Mar 30, 2016 10:21 pm

Gregory looks really good ,never tried extra mirrors to deflect the laser from mirror drum to mirror drum or screen i just got the laser to hit the line mirror reflect to the frame mirror then screen ,screen distance gave what ever size wanted ,distance drops your laser light .
Laser type 20 50 mW or more if you are brave , only tried red and ......uv on a glow screen ,what i had handy.....a green laser i had once seemed very bright perhaps we see this colour best ?
All will work but you need to be able to access the diode ,when i was doing my mechanical sstv i had to cut open the lasers case to bypass the electroncs to modulate the laser so what ever you get need to be able to focus defocus it and the above.don't make my mistake.
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: Mini version of Scophony - its do-able

Postby Gregory » Thu Mar 31, 2016 10:38 pm

Harry Dalek wrote:Laser type 20 50 mW or more if you are brave , only tried red and ......uv on a glow screen ,what i had handy.....a green laser i had once seemed very bright perhaps we see this colour best ?

Hi Harry,

Ideally it would be nice to do a white laser, from red, green and blue combined. A guy on U-tube made one, so its possible, I believe you need 2 dicroic filters to combine the colors, but I'm not too well up on the subject. Anyway this will have to be for a future project, as budget will not allow for now.

Yes I think green is the best color, so most probably go for this, as soon as I get The mirrors spinning and I know I can get a steady raster.
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Re: Mini version of Scophony - its do-able

Postby Harry Dalek » Fri Apr 01, 2016 8:52 am

Gregory wrote:
Harry Dalek wrote:Laser type 20 50 mW or more if you are brave , only tried red and ......uv on a glow screen ,what i had handy.....a green laser i had once seemed very bright perhaps we see this colour best ?

Hi Harry,

Ideally it would be nice to do a white laser, from red, green and blue combined. A guy on U-tube made one, so its possible, I believe you need 2 dicroic filters to combine the colors, but I'm not too well up on the subject. Anyway this will have to be for a future project, as budget will not allow for now.

Yes I think green is the best color, so most probably go for this, as soon as I get The mirrors spinning and I know I can get a steady raster.


Green would give it a monitor look,yes just test it before you even mount it,
Can your circuit run the lasers intensity from zero up to full .
yes it is possible to do a colour laser monitor ,those filters are the problem ...i am not sure but the dual laser dvd drives use 2 lasers IR and red and they use a system of tiny mirrors filters to do the same thing direct 2 different lasers from two directions to the same place the lens ,,,might work but never tried .
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: Mini version of Scophony - its do-able

Postby Gregory » Sun Apr 03, 2016 5:59 am

Should get the stationary mirrors and mounts cut and mounted this week, also a back panel to mount the laser diode and PCBs, when completed.

Harry, I have been looking more into laser diodes and you are definitely right, green laser diodes gives the brightest colour for a given power The doc file below downloaded from the web compares different colours of laser diodes and their visibility, and from what they say a 5 mw 555 nm green diodes is eguivelent to a 20 mw 635nm red diode in terms of brightness, so a 20 mw or 50 mw green diode should do the job. Also it seems green diodes are made from a different process from red ones, which makes driving them somewhat easier.

Laser diodes visbility.doc
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Re: Mini version of Scophony - its do-able

Postby Steve Anderson » Sun Apr 03, 2016 11:46 am

A word to the wise... you can't modulate a laser diode quite in that same way you would modulate a conventional LED. They depend on a certain minimum level of current to trigger the lasing process. Below this lasing current they behave like a very inefficient normal LED.

In this case as the raster is being spread out across an area so this may not be an issue, but I thought I would raise the point. There is a way around this - you can cross that bridge when you get there.

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Re: Mini version of Scophony - its do-able

Postby Gregory » Mon Apr 04, 2016 6:34 am

Thanks for the info Steve,

Perhaps when I finish the mechanics and scanning and get nearer to the laser modulation, you may have some suitable circuitry to suggest. I am at the moment looking to get a couple of 50 mw green laser diodes / pointers or modules, but there are so many out there, the choice will not be easy, especially on a minimal budget.
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