Back to the IR light source concept...

In article ,
(Chris Hodges) wrote:

Don Bruder wrote in message
...
snip
After spending some time looking for, and a grand total of 8 dollars
acquiring, a few of these "black" CDs, I went to work on taking my idea
from the realm of theory to reality. And I'm pleased to say "it works!"
snip

So at this point, I'm trying to figure out the best way to polish out
the scratches left by the steel wool, and get back to a truly
transparent (rather than translucent) finish on my homemade "filter".

Have you tried (in other words it probably won't work, but you never
know) aplying a water based clear varnish to the ground side.

Not an actual "varnish", but the transmission DID seem at least somewhat
better during my "pre-testing testing" - before I managed to get all the
40-weight washed off the piece. I was kinda half-considering trying to
shellac/varnish/clear-coat the thing in hopes of filling the scratches,
but haven't really made a lot of progres on the idea since the initial
"feasibility study", due to being handed yet another fistful of "hot
irons" to add to my "fire".

Another couple of options I've pondered, but haven't really gone
anywhere with so far are flame-polishing (before I try that, I'll need
to do some playing to figure out if it even *CAN* work for this
material) and coats of beeswax (Got plenty of that available, for
nothing more than the effort of going out to the hive and pulling a
frame...) or perhaps a beeswax/alcohol mix similar to varnish/shellac.

This is clearly going to end up being one of those "ongoing project"
projects - As I've got time, ambition, and materials, I'll probably
tinker with it on and off for the next year or so, until I either get
bored, or get it to what I consider "done enough".

If the
refractive index is similar enough to the plastic (tinted
polycarbonate I would guess - normal polycarbonate has n~1.56) and you
can get good coverage right into the grooves (you might need to dilute
with water) AND you get an even layer it might be good enough - it's
light delivery, not imaging that you're after. Underdriving the bulb
will increase the amount of IR at the expense of vis as previously
mentioned, so perhaps the bulb from a 4 or 6 cell maglite would help
as well.

Counterintuitive...

I don't see an underdriven filament putting off a larger *ABSOLUTE*
quantity of IR - Rather, I see the relationship between mount of IR and
visible output changing - As in the IR output stays (nearly) the same
regardless of voltage, but the visible component falls off with the
voltage drop until the point where visible output is nearly nil, but the
IR output is just as strong as ever.

That's not much different than running a filter - No net increase in
absolute brightness, but a relative increase in IR output compared to
visible. At some point beyond that (exactly where, I'm not sure, but I
*KNOW* that point MUST exist) the IR output is going to start dropping
along with the voltage.

The "increase IR versus visible output" concept is good. But how does
dropping the voltage *INCREASE* the actual IR output? Or is it as I say
above - namely, the IR radiation stays (pretty much, and only down to a
certain point) the same, but I don't have to "work so hard" to remove
the smaller amount of visible light to get near-pure IR?

--
Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See http://www.sonic.net/~dakidd/main/contact.html for full details.

In article ,
(Chris Hodges) wrote:

Don Bruder wrote in message
...
snip
After spending some time looking for, and a grand total of 8 dollars
acquiring, a few of these "black" CDs, I went to work on taking my idea
from the realm of theory to reality. And I'm pleased to say "it works!"
snip

So at this point, I'm trying to figure out the best way to polish out
the scratches left by the steel wool, and get back to a truly
transparent (rather than translucent) finish on my homemade "filter".

Have you tried (in other words it probably won't work, but you never
know) aplying a water based clear varnish to the ground side.

Not an actual "varnish", but the transmission DID seem at least somewhat
better during my "pre-testing testing" - before I managed to get all the
40-weight washed off the piece. I was kinda half-considering trying to
shellac/varnish/clear-coat the thing in hopes of filling the scratches,
but haven't really made a lot of progres on the idea since the initial
"feasibility study", due to being handed yet another fistful of "hot
irons" to add to my "fire".

Another couple of options I've pondered, but haven't really gone
anywhere with so far are flame-polishing (before I try that, I'll need
to do some playing to figure out if it even *CAN* work for this
material) and coats of beeswax (Got plenty of that available, for
nothing more than the effort of going out to the hive and pulling a
frame...) or perhaps a beeswax/alcohol mix similar to varnish/shellac.

This is clearly going to end up being one of those "ongoing project"
projects - As I've got time, ambition, and materials, I'll probably
tinker with it on and off for the next year or so, until I either get
bored, or get it to what I consider "done enough".

If the
refractive index is similar enough to the plastic (tinted
polycarbonate I would guess - normal polycarbonate has n~1.56) and you
can get good coverage right into the grooves (you might need to dilute
with water) AND you get an even layer it might be good enough - it's
light delivery, not imaging that you're after. Underdriving the bulb
will increase the amount of IR at the expense of vis as previously
mentioned, so perhaps the bulb from a 4 or 6 cell maglite would help
as well.

Counterintuitive...

I don't see an underdriven filament putting off a larger *ABSOLUTE*
quantity of IR - Rather, I see the relationship between mount of IR and
visible output changing - As in the IR output stays (nearly) the same
regardless of voltage, but the visible component falls off with the
voltage drop until the point where visible output is nearly nil, but the
IR output is just as strong as ever.

That's not much different than running a filter - No net increase in
absolute brightness, but a relative increase in IR output compared to
visible. At some point beyond that (exactly where, I'm not sure, but I
*KNOW* that point MUST exist) the IR output is going to start dropping
along with the voltage.

The "increase IR versus visible output" concept is good. But how does
dropping the voltage *INCREASE* the actual IR output? Or is it as I say
above - namely, the IR radiation stays (pretty much, and only down to a
certain point) the same, but I don't have to "work so hard" to remove
the smaller amount of visible light to get near-pure IR?

--
Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See http://www.sonic.net/~dakidd/main/contact.html for full details.

So at this point, I'm trying to figure out the best way to polish out
the scratches left by the steel wool, and get back to a truly
transparent (rather than translucent) finish on my homemade "filter".

Is there a reasonably easy way to do so? I don't know... I went after
the thing with 4-0 steel wool - as fine as I know how to locate - under
a layer of 40-weight motor oil, and although I did my best to avoid
excessive scrubbing (and therefore, scratching) I ended up with a
semi-matte, and therefore semi-translucent, finish on the filter. My
next move is probably to a 2400-grit wet/dry sandpaper that bills itself
as "Mirror-Brite", and to the touch, feels just about as abrasive as a
sheet of regular printer paper.

From there, my guess is that I'm going to need to move to something like
rubbing compound, rottenstone, or even ultra-fine jeweler's rouge.

Does this seem reasonable to those who have done optical grinding work?

Or am I way off base here?

Some modern automobiles use a plastic headlight assembly that 'fogs'
with age.. some fog fairly quickly. Inexpensive kits are become
available to polish the plastic lenses back to clear.. if the
scratches aren't too deep on your lens, this might work for you.

Search on fogged headlight lenses... here's one product..

http://www.autodetailingsolutions.co...astic_care.htm

Hope this helps..

Jim

So at this point, I'm trying to figure out the best way to polish out
the scratches left by the steel wool, and get back to a truly
transparent (rather than translucent) finish on my homemade "filter".

Is there a reasonably easy way to do so? I don't know... I went after
the thing with 4-0 steel wool - as fine as I know how to locate - under
a layer of 40-weight motor oil, and although I did my best to avoid
excessive scrubbing (and therefore, scratching) I ended up with a
semi-matte, and therefore semi-translucent, finish on the filter. My
next move is probably to a 2400-grit wet/dry sandpaper that bills itself
as "Mirror-Brite", and to the touch, feels just about as abrasive as a
sheet of regular printer paper.

From there, my guess is that I'm going to need to move to something like
rubbing compound, rottenstone, or even ultra-fine jeweler's rouge.

Does this seem reasonable to those who have done optical grinding work?

Or am I way off base here?

Some modern automobiles use a plastic headlight assembly that 'fogs'
with age.. some fog fairly quickly. Inexpensive kits are become
available to polish the plastic lenses back to clear.. if the
scratches aren't too deep on your lens, this might work for you.

Search on fogged headlight lenses... here's one product..

http://www.autodetailingsolutions.co...astic_care.htm

Hope this helps..

Jim

Don Bruder wrote in message ...
I don't see an underdriven filament putting off a larger *ABSOLUTE*
quantity of IR - Rather, I see the relationship between mount of IR and
visible output changing - As in the IR output stays (nearly) the same
regardless of voltage, but the visible component falls off with the
voltage drop until the point where visible output is nearly nil, but the
IR output is just as strong as ever.

I'll try and model this and get back to you - but if it's battery
driven (i.e. if you really want to use the maglite) it will improve
battery life.

Chris

Don Bruder wrote in message ...
I don't see an underdriven filament putting off a larger *ABSOLUTE*
quantity of IR - Rather, I see the relationship between mount of IR and
visible output changing - As in the IR output stays (nearly) the same
regardless of voltage, but the visible component falls off with the
voltage drop until the point where visible output is nearly nil, but the
IR output is just as strong as ever.

I'll try and model this and get back to you - but if it's battery
driven (i.e. if you really want to use the maglite) it will improve
battery life.

Chris

On Sat, 31 Jul 2004 20:43:22 GMT, Don Bruder wrote:


Now to refine the idea...

Although the "filter" I built is functional, it seems to be doing a bit
too good of a job in scattering the light - Almost certainly due to the
fact that my method of removing the reflective material from the base
plastic of the CD left what's probably best described as a crude "ground
glass" finish on it - Instead of being the usual pristine "It's so
clear, it's like nothing is there at all" plastic, my scrubbing to
remove the coating has created a more-or-less matte finish that doesn't
transmit anywhere near as well as I had hoped. Kind of like a lens that
has somehow escaped from its proper holder, then spent the last few
months bouncing around in the bottom of your ditty-bag with all kinds of
things that a lens isn't supposed to associate with if it's going to
remain unscratched and clear until it has become "frosted" by all the
scratches it has acquired.

So at this point, I'm trying to figure out the best way to polish out
the scratches left by the steel wool, and get back to a truly
transparent (rather than translucent) finish on my homemade "filter".

Is there a reasonably easy way to do so? I don't know... I went after
the thing with 4-0 steel wool - as fine as I know how to locate - under
a layer of 40-weight motor oil, and although I did my best to avoid
excessive scrubbing (and therefore, scratching) I ended up with a
semi-matte, and therefore semi-translucent, finish on the filter. My
next move is probably to a 2400-grit wet/dry sandpaper that bills itself
as "Mirror-Brite", and to the touch, feels just about as abrasive as a
sheet of regular printer paper.

From there, my guess is that I'm going to need to move to something like
rubbing compound, rottenstone, or even ultra-fine jeweler's rouge.

Does this seem reasonable to those who have done optical grinding work?

Or am I way off base here?

---
You're probably OK, if you want to go through the ritual of
never-ending polishing, but there _are_ commercially available
polishing compounds out there which might make your life easier.

Check out

http://www.noscratch.com/novus/index.shtml

Or, you might want to go a completely different route and use an
acrylic designed specifically for the purpose.

Cyro Industries has infrared transmitting acrylic, "ACRYLITE GP" with
a color # of 1146-0 which ought to work for you. Check this out:

http://cyro.custhelp.com/cgi-bin/cyr..._search_type=3

for spec's.

--
John Fields

In article ,
(Chris Hodges) wrote:

Don Bruder wrote in message
...
I don't see an underdriven filament putting off a larger *ABSOLUTE*
quantity of IR - Rather, I see the relationship between mount of IR and
visible output changing - As in the IR output stays (nearly) the same
regardless of voltage, but the visible component falls off with the
voltage drop until the point where visible output is nearly nil, but the
IR output is just as strong as ever.

I'll try and model this and get back to you - but if it's battery
driven (i.e. if you really want to use the maglite) it will improve
battery life.

Well, the whole point of this concept is a portable unit, so battery
power is probably the only reasonable way I can go. Nothing says it
*HAS* to be a maglight - that was just my "proof of concept" whack at
the problem - but it probably will have to be battery powered to make it
practical/portable.

--
Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See http://www.sonic.net/~dakidd/main/contact.html for full details.

In article ,
John Fields wrote:

Or, you might want to go a completely different route and use an
acrylic designed specifically for the purpose.

Cyro Industries has infrared transmitting acrylic, "ACRYLITE GP" with
a color # of 1146-0 which ought to work for you. Check this out:

http://cyro.custhelp.com/cgi-bin/cyr...p?p_sid=rANE2B
ih&p_lva=&p_li=&p_page=1&p_prod_lvl1=4&p_prod_lvl2 =6&p_cat_lvl1=%7Eany%7E&p_ca
t_lvl2=%7Eany%7E&p_search_text=1146-0&p_new_search=1&p_search_type=3

for spec's.

Hmmm... that one has possibilities, though I cringe at the idea of how
much $$ it will take to get ahold of the stuff... When looking at
IR-transmitting photographic filters, I was routinely spotting prices in
the $150-$200/6 inch square range for plastic filters - Which is why I
ended up going with a "make-do" chopped out of a black CD-R. Even the
gell filters (which are very likely to have *VERY* short working
lifespans) to transmit IR were ridiculously priced - a 70MM round was
tagged at $89, fergawdsake! My budget (which is mostly imaginary,
practically speaking) for this project can't even CONSIDER those kind of
prices! And glass? HAH! If I can't afford the "cheap" gells and/or
plastic, then I don't even need to consider glass, since that seems to
routinely be about 130-200% more expensive than the corresponding
plastic filter.

Now to see if I can find someplace that will tell me how much this
"Acrylite" stuff costs... I note a glaring lack of any reference to
pricing for it at the link you posted. Most often, I've found that
situation to be a red-flag for "If you need to ask "how much?", it's
more than you can afford. Have a nice day, and don't let the door hit
you in the arse as you leave." materials.

Still, now that I know the stuff exists, I might be able to find
someplace that sells it in reasonable quantities, at reasonable prices.
More investigation is in order, obviously...

--
Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See http://www.sonic.net/~dakidd/main/contact.html for full details.

Don Bruder wrote in message ...
In article ,
(Chris Hodges) wrote:

Don Bruder wrote in message
...
I don't see an underdriven filament putting off a larger *ABSOLUTE*
quantity of IR - Rather, I see the relationship between mount of IR and
visible output changing - As in the IR output stays (nearly) the same
regardless of voltage, but the visible component falls off with the
voltage drop until the point where visible output is nearly nil, but the
IR output is just as strong as ever.

I'll try and model this and get back to you - but if it's battery
driven (i.e. if you really want to use the maglite) it will improve
battery life.

Well, the whole point of this concept is a portable unit, so battery
power is probably the only reasonable way I can go. Nothing says it
*HAS* to be a maglight - that was just my "proof of concept" whack at
the problem - but it probably will have to be battery powered to make it
practical/portable.

I modelled the blackbody curves in excel, and you're right, by quite a
margin - I don't know whether the power requirement or the IR output
would fall faster for a given emitter as you drop the temperature
(assuming temperature control for convenience) so it might not even
save battery life.

The maglite could be a good way to go - the focussing output would
seem to help, even if you have a diffuser effect from the vis blocking
filter.

Did you ever try multiple visible gel filters - these tend to be cheap
(I seem to remember £10 (~$18)/sq foot), and for a maglite even
offcuts would be enough, so even cheaper if you have a friendly
theatrical/DJ supplies shop that does stage lighting.
e.g. Lee filters (www.leefilters.com) "Blood red 789" transmits only
1% visible in the far red, combine with (e.g.) "Bray blue 722" should
do it. I found my old swatch book recently (since the last thread) so
I can have a look with a lamp and digital camera later. With anything
less than hundreds of watts they'll last forever.

Chris