Collimating SCT.

[Ian]

Chris is that fibre-optic cable for data?

The reason I ask is it's usually sheathed with kevlar. it's a pain to cut, coz you can't easily without the right tools and if you try to break it with your hands it can cut like cheese wire.

That said, it'd be fun to play with as well

[Rocket Pooch]

nope pvc

[Mac]

EACH OF THE 64 STRANDS IS 0.25mm DIAMETER

it will be interesting to see if you can pull the fibres out thinner with a little heat,
I've got some borat sillica glass, (glass blowers glass), which is what i used, as i said the fibre i was left with was about 0.2mm but the end piece broke off,
and was a lot thinner.
I used this at a distance of about 50ft ish.
I'm going to get some stiff card tomorrow and have a go at making that collimating mask,
I'll post the comparison results later.

Mac.

[JohnP]

High Five...!!!! 

[Rocket Pooch]

Hi,

I also have made on using some 25nm fibre optic and a 9v battery, 1x48 ohm resister a switch and a supper bright led, works a treat, but I spent the last hour mucking about with my 6" primary, and now I need to optically collimate the primary again it was out, I very nearly got the collimation 100%.

But if you try really hard you can get your newt to do this.

[Mac]

25nm fibre optic

Thats *!£"%&&^% small.
are you sure thats the correct size!
the wavelength of light is between 400 & 800 nm
1mm = 1,000,000 nm
.01mm = 10,000 nm

[Ian]

I'd put money on it being 25 micron. The thinnest data carrying fibre I've worked with is 9 micron. And no, I don't have any I'm afraid, I wish I had...

[Rocket Pooch]

ok ok 25 micron, still worked a treat though, you could actually see it like a little mag 4 star at the end of the garden, ahhhhhhhh,

[MarkS]

Is this idea any good (laser diode from cheap LED laser pointer)
http://www.oldham-optical.co.uk/Red_Light_Source.htm

I suppose it depends on whether the light emitting bit of the LED is smaller than the 25microns you have already achieved.  How does one find out?

Mark

[Rocket Pooch]

The LED goes into a tube, the fibres go into the other end and then I have cut all but one of the fibres, the only light that comes out is from 1 fibre.

chris

[MarkS]

Chris,

If you have any left - I'll buy a few fibres.

Mark

[JohnP]

Chris 48 ohm at 9V works out at 9/48 or 0.1875Amps which is an awful lot of current for an LED - I would have limited the current to something like 20mA (as discussed) & so used a 400-500 ohm resistor...

Looks good though...

John

PS - Can't slag you off about your nm V's micro-meter slip up I screwed up the other day with Arcmins & ArcSecs.....

[Rocket Pooch]

It would not even go on with a 500ohm one they seriously chuck out light I almost blinded myself.

And my newt focuses to within 40 feet?  Odd that.

Anyway, the said device prototype will be on display the weekend for all to laugh at!  And I need a volunteer to help me collimate the primary on the 6".

[Rocket Pooch]

Just checked the web site said 48ohm.

[Ian]

the max forward current is specified in the datasheet for the part. I had a quick look on maplins site for superbright LEDs and the max current was in the region of 0.1A. Don't forget when calculating the voltage across the resistor=battery voltage - forward voltage drop across the LED. The forward voltage drop can also be found on the datasheet for the part.

Alternatively, build a constant current supply...