Lens Disk idea

Anything not specifically related to NBTV, but at least of some technical nature that might be of interest to NBTV members. Items for sale and links to retailers do not belong here.

Moderators: Steve Anderson, Dave Moll

Lens Disk idea

Postby Harry Dalek » Thu Nov 29, 2012 9:35 pm

I was wondering if it was possible to make a plastic lens for a nipkow looking into it after reading one of the first newsletters it can be done but being a bit slack i would rather buy or substitute if i had any thing handy .

I have some tiny lens removed from this and that but no large amount and same size for a Nipkow lens so been looking into any thing handy in my parts box.

Leds came to mind a while ago due to the dome shape thinking so they must be able to focus light at its focal point but never really looked into it till now the colour ones don't seem to good from a quick look but i had some UV and high brightness crystal clear ones ...these seem spot on they have a focal point of around 10mm .....a guess have to get my ruler out !

I was thinking the insides the LED or the leads you'd cut away would block the light perhaps it does in part but at a slight angle works rather well as a lens....

Would be pretty easy to mount in a nipkow as well i am thinking camera BTW so would make a safe lens disk and Garys spiders would be safe

:wink:

Next step would be try it out i guess.
Attachments
Screen 00016.jpg
Screen 00016.jpg (9.4 KiB) Viewed 4907 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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4082
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Postby gary » Thu Nov 29, 2012 9:47 pm

1) why would you use these instead of acrylic balls?

2) why would they be easier to mount?

3) why would they be safer than balls?
Perfecting an NBTV system is like trying to slam a revolving door...
User avatar
gary
"Fester! Don't do that to 'Thing'"
 
Posts: 2303
Joined: Sat Jan 27, 2007 11:29 am
Location: Bundanoon, Australia

Postby Harry Dalek » Thu Nov 29, 2012 10:02 pm

1) why would you use these instead of acrylic balls?


I have these handy and free easy to get .

2) why would they be easier to mount?


Because Gary they have a beveled edge and the end of them if thats the right word ......a stopper.. drill right and its in place.

3) why would they be safer than balls?


Well balls would slide either way if the holes not 100 % could go flying ,i think it would be hard to work out a balls middle position right......due to the shape of the led and the stopper you know its end even if you have drilled and its a bit loose due to the beveled edge that could be glued easier than a something round.
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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4082
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Postby gary » Thu Nov 29, 2012 10:17 pm

harry dalek wrote:
I have these handy and free easy to get .



But modifying them would be time consuming with no guarantee of optical accuracy. Also, down the track you may need LEDs and have to go and buy them.

optically accurate acrylic balls can be had, even in Australia where everything is 5 times the price of anywhere else, for a few cents each. If you buy them from the US they are, well about 5 times less if not more.

Because Gary they have a beveled edge and the end of them if thats the right word ......a stopper.. drill right and its in place.


Drill right and a ball is in it's place - I don't see how a bevel would help - in any case how would you remove the guts of the led without destroying the optical integrity?


Well balls would slide either way if the holes not 100 % could go flying ,i think it would be hard to work out a balls middle position right......due to the shape of the led and the stopper you know its end even if you have drilled and its a bit loose due to the beveled edge that could be glued easier than a something round.



The balls don't move because you make the holes slightly undersized.

It is easy to make the apertures slightly undersized such that the balls fit in snugly - they are perfectly sized. You simply step out a hole with successively larger drill bits until you find a snug fit and then you use that as your final dill bit size - easy peasy. I don't use that method because I can CNC them.

No one I know of who have used them have ever had a ball fly out of it's own accord.

You don't want to use glue because it invariably will get on the optical part of the lens and ruin it.


EDIT: Oh, and if the hole is loose for some reason it is easy to reduce in size by:

a) adding a little paint on the inside of the hole if only slightly large

b) using a a centre punch around the hole to reduce the size if fairly loose.
Perfecting an NBTV system is like trying to slam a revolving door...
User avatar
gary
"Fester! Don't do that to 'Thing'"
 
Posts: 2303
Joined: Sat Jan 27, 2007 11:29 am
Location: Bundanoon, Australia

Postby Harry Dalek » Thu Nov 29, 2012 10:52 pm

But modifying them would be time consuming with no guarantee of optical accuracy. Also, down the track you may need LEDs and have to go and buy them.


No need to modify just cut the wires off snip snip that the beauty of it the insides do not seem to effect it no need to touch the led or i would not even bother .


optically accurate acrylic balls can be had, even in Australia where everything is 5 times the price of anywhere else, for a few cents each. If you buy them from the US they are, well about 5 times less if not more.


I didn't know that but i still rather this if it works even sacrificing 32 leds for the good of NBTV :wink:


Drill right and a ball is in it's place - I don't see how a bevel would help - in any case how would you remove the guts of the led without destroying the optical integrity?


No Need to do any thing to the led Gary at all if you have one handy try it out has to be the clear ones as in post photo, works both ways but i think a camera the flat would be the front and round to the light sensor as i found the focus worked well that way when doing a light focus test.

The balls don't move because you make the holes slightly undersized.


A ball has no end so still think it would be harder to mount correctly by the average NBTVER than something that once you know pushes in and stops at the correct position..but you are right in that sloppy work is not good for either ......point being get the right drill bit .

It is easy to make the apertures slightly undersized such that the balls fit in snugly - they are perfectly sized. You simply step out a hole with successively larger drill bits until you find a snug fit and then you use that as your final dill bit size - easy peasy. I don't use that method because I can CNC them.


My point is most of us don' t have great tools for the old hobby Gary what ever makes it easier might make it work ..yes even the right drill bit might depend on the users drilling skill.

No one I know of who have used them have ever had a ball fly out of it's own accord.


I was only joking Gary about the spider story you told me once i always remembered that sort of put me off lens disks ...i was thinking must get safety Glasses if i ever try .

You don't want to use glue because it invariable will get on the optical part of the lens and ruin it. :wink:


Yes i like the idea of just pushing them in what ever makes it easier is fine with me .
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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4082
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Postby gary » Thu Nov 29, 2012 11:10 pm

I was only joking Gary about the spider story you told me once i always remembered that sort of put me off lens disks ...i was thinking must get safety Glasses if i ever try .


But you seem to have forgotten that I had to run a camera lens into it to have that happen - the same thing will happen with the LEDS - perhaps worse.

Unless there is severe physical trauma to the beads they will stay in place.

I just wanted to make it clear that bead disks are inherently safe.

BTW no great skill is required using the method I described - read Doug Pitt's article.

If you can make a nipkow disk you can make a bead disk - in fact I reckon it's much easier because the holes are so much larger no fine drill bits or hacked needles required.
Perfecting an NBTV system is like trying to slam a revolving door...
User avatar
gary
"Fester! Don't do that to 'Thing'"
 
Posts: 2303
Joined: Sat Jan 27, 2007 11:29 am
Location: Bundanoon, Australia

Postby M3DVQ » Fri Nov 30, 2012 2:10 am

I wonder, if you had two discs machine cut with accurately positioned holes could you counter sink them so that a bead can be sandwiched inside?

This would solve the problem of how to fix them without gluing and without scratching or distorting the beads pushing them in.

I would think sheet plastic should work for these discs, perhaps HDPE or ABS. How accurately they could be routed out and CNC drilled/countersunk though I don't know.
Attachments
bead.PNG
bead.PNG (2.94 KiB) Viewed 4882 times
M3DVQ
Just nod and pretend you understand me
 
Posts: 326
Joined: Sat Feb 10, 2007 10:52 am
Location: Lincolnshire

Postby Harry Dalek » Fri Nov 30, 2012 7:15 am

gary wrote:
I was only joking Gary about the spider story you told me once i always remembered that sort of put me off lens disks ...i was thinking must get safety Glasses if i ever try .


But you seem to have forgotten that I had to run a camera lens into it to have that happen - the same thing will happen with the LEDS - perhaps worse.

Unless there is severe physical trauma to the beads they will stay in place.

I just wanted to make it clear that bead disks are inherently safe.

BTW no great skill is required using the method I described - read Doug Pitt's article.

If you can make a nipkow disk you can make a bead disk - in fact I reckon it's much easier because the holes are so much larger no fine drill bits or hacked needles required.



No worries Gary

What ever you use and it works is just another good use for NBTV i am always for that ....

Yes not good running into a rotating one of these ! i wonder if Baird had any of he's large lenses come out flying on any of he's tests ...being glass i should think they would of been deadly !

Well any case i will give my idea a shot when i have some time this weekend .

A normal nipkow reduces the light by 1000 doesn't it ....due to the size of the lens used light is of cause increased ...i suppose it now depends of how clear the plastic or glass and focusing .
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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4082
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Postby M3DVQ » Fri Nov 30, 2012 10:04 am

harry dalek wrote:i wonder if Baird had any of he's large lenses come out flying on any of he's tests ...being glass i should think they would of been deadly !


He certainly did. I believe it fired the lenses out at the walls causing them to exploded into glass shards, then the unbalanced disc jumped free of its mounting and ran around the workshop destroying everything in its path. :shock:
M3DVQ
Just nod and pretend you understand me
 
Posts: 326
Joined: Sat Feb 10, 2007 10:52 am
Location: Lincolnshire

Postby Lowtone » Fri Nov 30, 2012 12:19 pm

must be horrible :o
r a d i o P T T v i s i o n
User avatar
Lowtone
Just nod and pretend you understand me
 
Posts: 281
Joined: Sat Jan 16, 2010 9:45 am
Location: France

Postby Harry Dalek » Fri Nov 30, 2012 2:35 pm

M3DVQ wrote:
harry dalek wrote:i wonder if Baird had any of he's large lenses come out flying on any of he's tests ...being glass i should think they would of been deadly !


He certainly did. I believe it fired the lenses out at the walls causing them to exploded into glass shards, then the unbalanced disc jumped free of its mounting and ran around the workshop destroying everything in its path. :shock:



Well that would have been one bad day ! lucky he wasn't hit could of killed him out right.

I had a mirror come unstuck go flying that was bad enough.


I had a quick try at making the holes for the leds on a spare disk the original holes were pin prick size and i have drilled them out on the first test disk full size ,i think i should of used a smaller drill bit first then the larger one live and learn .
When hand making them i tend to make a few disks you end up with one or two with less mistakes
Attachments
Picture 490.jpg
Picture 490.jpg (91.04 KiB) Viewed 4865 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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4082
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Postby Harry Dalek » Fri Nov 30, 2012 3:08 pm

Just had another go and that worked much better ! i think i might have to have a paper backing or just use the encoder paper as these disks are a bit transparent with a lot of light the paper backing should block it outright.
Attachments
Picture 491.jpg
Picture 491.jpg (216.65 KiB) Viewed 4861 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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4082
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Postby Harry Dalek » Fri Nov 30, 2012 7:18 pm

Well i finished my first go at a finished one the led nipkow..perhaps i should do an Albert and call it the LEDKOW but not using the led part so might be cheating .

I'd be interested to try it out on the camera once i check its all working still.
Attachments
Picture 492.jpg
Picture 492.jpg (286.85 KiB) Viewed 4854 times
Picture 496.jpg
finished led nipkow
Picture 496.jpg (315.29 KiB) Viewed 4854 times
Picture 498.jpg
The back which is the front really !
Picture 498.jpg (270.85 KiB) Viewed 4854 times
Picture 502.jpg
Focusing
Picture 502.jpg (313.45 KiB) Viewed 4854 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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4082
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Postby Steve Anderson » Fri Nov 30, 2012 11:13 pm

I will be the first to admit I've only skimmed through the previous, but how do you plan to get power, signal (and perhaps) commutation info to these LEDs? Irrespective of their optical performance. Not being negative, just curious...please don't say slip-rings...

Steve A.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 3833
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Postby AncientBrit » Fri Nov 30, 2012 11:18 pm

Steve,

I think he's using them as lenses only, back lit.

No actual signal excitation,

Cheers,

Graham
AncientBrit
Green padded cells are quite homely.
 
Posts: 858
Joined: Mon Mar 26, 2007 10:15 pm
Location: Billericay, UK

Next

Return to Off Topic

Who is online

Users browsing this forum: No registered users and 1 guest

cron