Mirror Camera project

[Harry Dalek]

I have been thinking about what Gary was saying on using the polygon first then the frame mirror and using it in reverse should show a raster .

I can't get my head around if it matters it should work visa versa ?

I have found an old example from my Octagon project so it must work in reverse if the laser is replaced with a light sensor this worked.

The uv laser hits the octagon mirror then the larger frame mirror its sort of what i am doing in reverse .

Still haven't got around to it but i'll get it out again one day and do a Flying spot camera test but i never got around to syncing the motors might get a camera picture for a second or two ...

I am wondering also looking at the old example of a camera with the frame mirror first drawing below if a lens is really needed ? I suppose you just move closer to subject but have no zoom. I do notice at how much light is lost in mine with that large lens .

[Dave Moll]

May I just say what an excellent animation showing how the light is deflected as it hits the sides of the rotating hexagonal mirror. Presumably there is a second mirror handling deflection in the other orientation - one rotating at one-sixth line speed and the other at the appropriate fraction of frame speed.

[Harry Dalek]

May I just say what an excellent animation showing how the light is deflected as it hits the sides of the rotating hexagonal mirror. Presumably there is a second mirror handling deflection in the other orientation - one rotating at one-sixth line speed and the other at the appropriate fraction of frame speed.

Hi Dave

Yes thats a good animation just needs that stationary mirror to be at least a 2 sided mirror 4 to 6 much better idea and you have a raster of different number lines depending on the speeds difference of mirrors.

I uploaded it once again forgetting to explain if this is my camera the light from the lens is the laser and the stationary a vibrating mirror and the 5 sided mirror my polygon its pretty much how it works apart from its a full line sweeping passed the light detector reason i need to see only a small area of that a dot of light.

Been scrapping some laser diodes and polarized glass and tiny lenses motors and such out of old dvd drives ,did a few tests today got 3 high powered lasers thanks to the scrapping ,testing on about 3 volts they partly go on then dim more than likely charging and discharging the laser diodes driver capacitor ,you rather run these things up from a low voltage to its running voltage for a start you have no idea what the correct voltage these things run at ,i have an idea but
again its best to be safe than sorry as far as safety gos ( never test a laser full power on a mirror project run it up only when it works if you enjoy your sight and good to for a start test the laser defocus no lens) and the life of the laser they seem fine at 5 volts rather under run them.
Thinking i might see if i can do a raster projection with it as well to test that vibrating mirror and it might end up being both types of camera at worst one what the hell the motor is synced FFS as well all i have to do is stick in a laser .

[gary]

I can't get my head around if it matters it should work visa versa ?

Not unless I am completely misunderstanding your arrangement.

You have a beam of light right?

the beam of light hits the *thin* line scanner and is reflected on a *wide* frame scanner which is perpendicular to the line scanner right?
The frame scanner is positioned in such a way that the line scan starts at one side of the mirror and ends at the other side such that the beam is always on the frame scanner mirror right?

If you go the other way the beam is frame scanned perpendicularly across the *thin* line scanner so most of the time it is missing the line scanner unless the frame scanner angle is very tiny and your video seems to imply that it is not.

I may be completely misreading your set up, but it is late for this old codger, so I am off to be, and will look again tomorrow, just confirm those things please.

PS As nice as your animation is it is only showing the line scanner - presumably it is a laser printer scanner and the frame scanning is done by the movement of the paper past the line scan.

[Harry Dalek]

I can't get my head around if it matters it should work visa versa ?
Not unless I am completely misunderstanding your arrangement.

You have a beam of light right?

Gary i tried to draw what i am seeing The lens projects the full image from the lens on to the frame mirror which rocks the polygon the line mirror only sees a strip of light that is reflected to it and depending on the angle of the frame image so it sees changes with that angle ,the polygon reflects the strip of light to the light box with a light sensor.
Because the strip of light from the polygon is so thick i only want the light sensor to see a tiny part of that polygon thick line and i also only want the light sensor to see a point of light from that line.

the beam of light hits the *thin* line scanner and is reflected on a *wide* frame scanner which is perpendicular to the line scanner right?

Well it would if the light sensor was a light reflecting from the polygon to frame mirror and out the lens in a FFS it would work that way i would need a thin mask line for the light ...thats why i was thinking of a laser much easier to do a quick FFS projector to see how the rocking mirror gos ...i sort of think it needs to run twice the frame speed to work correctly as of the fly back takes up half the time me thinks ; ).
I have never read in nbtv that a rocking frame mirror or sensor on a rod has this problem and it had me interested ....i know with my laser monitor change the speed slower you see more lines slowing it down you still see a picture but it is compressed due the larger number on lines the effect has me wondering does or will it look or work at all the same on a camera idea or work at all.

The frame scanner is positioned in such a way that the line scan starts at one side of the mirror and ends at the other side such that the beam is always on the frame scanner mirror right?

Yes the frame mirror just rocks so the light line angle of the image will be scan up or down the image depending on how much the frame mirror can rock .

If you go the other way the beam is frame scanned perpendicularly across the *thin* line scanner so most of the time it is missing the line scanner unless the frame scanner angle is very tiny and your video seems to imply that it is not.

Gary i am making up for the thickness and size of the mirrors polygon and frame mirror by the size of light the light sensor sees i have gone with an examples i have seen in drawings in the newsletters most of the time you never see the results but take their word for it ,so i will try that and see if it works for me .
I still have 2 other ideas in case the pin hole camera light box on a direct light camera causes me grief ,i will try a vertical mask thin line instead of the light dot and would rather a dvd lens in place of the pin hole idea if that works.
Also increasing light levels i see in a past drawing i posted the main lens ma not be needed well a film pin hole camera doesn't either .

I may be completely misreading your set up, but it is late for this old codger, so I am off to be, and will look again tomorrow, just confirm those things please.

Have a look at m drawing i know i am dreadful at drawing but think it sort of make it out , i know i am also bad at optics but i enjoy things that are a bit harder reason i like controlling rotating things .

PS As nice as your animation is it is only showing the line scanner - presumably it is a laser printer scanner and the frame scanning is done by the movement of the paper past the line scan.

Yes i just used it as it is sort of what i am doing it i replaced the words with lens rocking mirror polygon and solar cell in light proof box.

I will stick with it its a good test bed for ideas, i haven't checked Yet if the pin hole light box works apart from testing the light levels from what i did i think it would work with a simpler lens no lens or more light but i really have to see again using Big picture or our tiny viewer.

The laser FFS idea i am interested in to as it would not be hard to ad a laser diode to this and project a raster and as i said before really see what a rocking mirror works well enough.

[Harry Dalek]

Bit of a OH moment today....as i said in the last post optics is not my forte unfortunately ,playing around with some lenses from behind the main lens i was getting really no where as i was not sure i was focusing as the light i am using is an array of leds and i was thinking i should be able to focus these at the first mirror at least or i will get no where with reflecting light .
I didn't really think about it before as i was getting a nice focus to my eye looking from behind boy was i wrong !

Well i tried a half lens in the front of the main lens and bingo i have projection focus to the first mirror..... looking a paper screen i put there to see now have a wide distance range as well.

Pictures might help others if your a dumb dumb on optics like me

And BTW just that lens would work without the zoom lens i am using you would just have to have it in a tube and adjust the distance for a focus.

The first picture is the lens that helped me ,the plastic one behind gave me the the first results...the glass one is from an old slide projector.

I have now close up focus and distance how distant we will see.
I have just seen the focus after the second mirror so far so good.

[gary]

Harry, that last diagram you drew seems almost perfect - the only thing missing is the lens that focuses the image onto the plate that has the pin hole in it. If the polygon was wide enough you would see the whole image but as it is not you will just see a bar of it I suppose - but if it is in focus I can't see why it would matter.

The only thing is whether the relationship between the polygon and the rocking mirror is such that the whole image traverses the pin hole, but once you get a lens in there it should be easy to see that and make adjustments as necessary.

Also make sure that the light is projected onto the sensitive surface of the photocell and not on or across the "divides".

Suggestion: replace the photocell with a bright white led - that should throw a point of light up on the wall (or whatever) and trace out a raster - then post up a well lit white sheet of paper with some large letters on it (NBTV ), replace the led with the photocell and make sure a bar of the paper image is thrown on pin hole plate and adjust lens for perfect focus if necessary.

Oh but the lens at the front of the system is not necessary I don't think.

[Harry Dalek]

Harry, that last diagram you drew seems almost perfect - the only thing missing is the lens that focuses the image onto the plate that has the pin hole in it. If the polygon was wide enough you would see the whole image but as it is not you will just see a bar of it I suppose - but if it is in focus I can't see why it would matter.

Hi gary

Thanks Gary i was figuring the pin hole camera didn't need a lens and i have focus movement on that dvd door opener to and fro.

I think i really stuffed up on the lens at the start i would say now it was so way out of focus to the first mirror all i was getting was a very very blown up out of focus image ,just getting a bit of light no detail of any thing .
Its sort of caused a run away change of designs with the light sensor where i should of started say like Troy did projecting an image to see that part worked in the first place ,Oh well live and learn

The only thing is whether the relationship between the polygon and the rocking mirror is such that the whole image traverses the pin hole, but once you get a lens in there it should be easy to see that and make adjustments as necessary.

Yes the rocking mirror is a big if i suppose i should get some results at worse and yes again the amount of rocking distance ...i hope its enough for 32 lines or i will have a fair few black lines either side speculating.

Also make sure that the light is projected onto the sensitive surface of the photocell and not on or across the "divides".

OK i think i recall Klaas not liking this solar cell because of those bars ,but a pin hole camera the pin hole in the film camera acts as a lens from what i was reading it could act as the in the picture below because there is distance between the pin hole and the solar cell...
I still think the solar cell might be the best choice since it works best with the head amp circuit but rather a tiny lens for more light just see how it gos .

Suggestion: replace the photocell with a bright white led - that should throw a point of light up on the wall (or whatever) and trace out a raster - then post up a well lit white sheet of paper with some large letters on it (NBTV ), replace the led with the photocell and make sure a bar of the paper image is thrown on pin hole plate and adjust lens for perfect focus if necessary.

Arrr thats a great idea ,I did notice i had to refocus the to the polygon distance and again to the light sensor at distance a bit
I can now see projected light differences to the solar cell area this is good.
I did this last experiment today with the simple leds moving up and down .

Oh but the lens at the front of the system is not necessary I don't think.

I think the large projector lens is needed on the front of my old tv camera lens only because of the distance to the first mirror is wrong without it with out it all i get is a dull white light i forgot to take a picture of that must be way out of focus no wonder i was get such low light levels .

[gary]

Harry, I base my recommendations for the lenses on what is normally used for a Weiller style mirror drum, after all your arrangement is really the same but with the line and frame scanning separated out. The only thing I am not confident about is the effect of the separation between the line and frame scanners - this is definitely one of those projects where for me it would be a suck it and see procedure...

See Newsletter Volume 3/4

[Harry Dalek]

Harry, I base my recommendations for the lenses on what is normally used for a Weiller style mirror drum, after all your arrangement is really the same but with the line and frame scanning separated out. The only thing I am not confident about is the effect of the separation between the line and frame scanners - this is definitely one of those projects where for me it would be a suck it and see procedure...

See Newsletter Volume 3/4

I have really only seen Allan Short's plans for separated line and frame cameras where he tended to use a movable light sensor on a rod doing the frame scan most of the time.

Its more than likely now worth another test and see ,its packed away tonight but may as well give it a go next time i get it out again .

Yep the lens system could now i see it in hindsight be very simple.

Now i have seen the lens system is working i am bit more hopeful, i know now i have something to put between those sync pulses//// how well it does that does depend on the line and frame scanning ,the line i am not to worried about but frame is going to be an experiment ,but thats the fun of it not knowing if it does good and fine if not theres always another way .

[Harry Dalek]

Hadn't had to much time to experiment lately ,i gave it a run last week no results so back to the optics and light sensor side of things .

So going to go back to basics and see what results i can detect doing all this nice and slow i figure its in a way not to different to a reflective opto sensor off a encoders light and dark areas ...signal no signal or in this case we have shades all between the two .

I tried this tonight in the photos to track down fault find my problems...perhaps not the best of slides to use but has a bit of of light and dark areas to sweep across the light sensors light hole .

Problems i have found ......

The frame mirror as it moves rocks down the light line from the polygon also moves down so i would only have the thickness of the polygons mirror before the light line is lost below the light sensors light hole .

I was not expecting this boy am i bad at optics

Seems a vertical slit instead of a hole might fix this .

ON the head amp working I can just hear the sensor picking up the light differences as i sweep this line of the image across it, its still very much so in the snow or white noise so if it did work at that light level it would be a snowy image.

So making this little slide projector with that light level which i suppose would be better than day light ? it still would not be good enough .

With more light say using a projector doing the same sort of thing could improve things.

Now what i have seen tonight i have a bit of a problem as is now as the frame mirror rocks and projects a light line to the polygon and the polygon to the light sensor area the light line moves down out of the light sensor hole area .......i was thinking a slit mask would fix this as the solar cells surface area is large but the polygons light would not be a tiny square but a longer rectangle ( . l )instead of that dot i would see that line in the bracket which would end up being a fair few lines thick .
Speculating masking of part of the polygons mirror to a slit or just another mask horizontal mask ....I sure have a bit of thinking.
May be i have the frame mirror sitting at the wrong angle ? as its sitting now if i have it vertical to start with perhaps the light line will stay reflected to the same place even with angle change .
If i ever get this working she will be a keeper ...

[Harry Dalek]

I suppose one way to learn is trial and error and review experiments of the past.
i can see Gary was right on the missing lens in my system between the polygon and the light detector .
Experiments this week instead of trying to increase the projection of the image to a size of my frame mirror just really drops the light level to the light detector i think there must be a correct size for accurate image line scanning and right amount of light levels your light detector can deal with.
I have gone the other way dropping the size of the projection image i can detect the light from the lens with room light ,with the new small lens in the system via going back to a photo diode to test .
I really wanted to see a mirror drum camera some one else has made but there is little, i have found so far an original version just to see the optics ...i found this plan from one of my books this seems pretty much what i have at the moment mirror lens sensor .
Some thing i am not sure about as optics isn't my thing i have really always wanted to use a mask less system for light levels any way ......is the photo trany or diode a point of light detector or does the lens focus all light across its surface area focus all the light to the photo sensitive area ...i am thinking it must be a point of light detector ?
I hope the answer is yes
My batteries are running down in my torch but you can see the torch leds reduced image size,it does help as i said in light detection but due to my poor optics know how i will have to do more tests to find out if its because of the full small image or part a point of that image at increased light levels due to being focused that is what i am hoping for .

[Harry Dalek]

I tried the first experiment today to see how the tiny focusing lens and photo diode worked together in a light proof tube.

The experiment is i wanted to see if moving the slide which has different light levels across the light so across the photo diodes light sensitive area i could pick up the changes in head amp.

So far so good that seems to work ,i next have to see how light reflecting off a simple test card with distinct shade differences which i suppose the levels will be lower but i know i can pick up a white paper well so i can pickup that being there and not just have to see if i get the similar results as the slide fingers crossed .

The lens tube has another that slides for focusing to the photo diode old textors casings do come in handy.

Will not have much time till next week to work more on it

[Harry Dalek]

The problems i have had on the optics and head amp i am a bit more hopeful now .

Seem to get results on a reflecting test to the polygon and vibrating mirror both running ,the video sound does seem right very much so on adjusting the frame mirror .

Like always a full run of it will show me either way .

I worked on the head amp light sensor part and neatened that up day and added a manual screw adjustment to frame vibrating relay mirror just to help or adjust the relays spring .

I will do a full video test tomorrow and report back.

[Harry Dalek]

I am still having problems so some thing is up

Time to use my secret weapon Garys advice Replacing the photo diode with a Led should show me if it still an optics problem...

I am a bit ify about the video sync mixer i am thinking of just input and outputting a good nbtv wav via it and see if the circuit is working correctly i suppose too i could do a frequency sweep would do the trick as well.

There should a standard procedure in last resort circumstances first pull ones hair out ,denial,depression,anger which must be controlled for your projects survival and the last resort take it to the shed unfinished for recycling

Well not at those stages yet just a little head scratching between the hair no guts no glory as they say ,camera projects are hard for a reason to keep NBTVers interested