-----Original Message-----
From: pcb-gcode@... [mailto:pcb-gcode@...] On
Behalf Of Gavin McIntosh
Sent: Friday, October 20, 2006 2:42 PM
To: pcb-gcode@...
Subject: RE: [pcb-gcode] Re: new to group/cutters, Lasers, LEDs and
Fluorescent tubes for PCBs

Alan,

Sharp have laser diode controller chips.
It depends on which way the internal photodiode is connected which chip
you
use.

Gavin

From: "KM6VV" <KM6VV@...>
Reply-To: pcb-gcode@...
To: <pcb-gcode@...>
Subject: RE: [pcb-gcode] Re: new to group/cutters, Lasers, LEDs and
Fluorescent tubes for PCBs
Date: Fri, 20 Oct 2006 07:56:12 -0700

HI Keith,

Thanks for the heads-up. Interesting, although I'm not sure where I'd
start
with it. 7mw doesn't seem like much power!

Yeah, the 3rd leg is a puzzle! Now if I could identify the chip that
controlled the laser diode, I might get somewhere. Can I ignore it?
Currently I don't even have a guess as to which pins are which.

Photosensitive resists (I've only looked at a couple) seem to be

sensitive

to 350-400 nm, and I've found an LED at 400 nm, so I might give that a

try.

'350BL fluorescent tubes for illumination seem to be popular. I'm slowly
seeing some correlations. At some point I'll just get some material and
experiment a bit. For now, I'm having a great time just milling my

boards!

Speaking of cutters, I just received a very nice looking pair of cutters
made by Andrew. I'll try them out on my next board. Maybe on the box

lid

that I just made for another RDF project.

Alan KM6VV

Behalf Of keith3125

Here's a cheap violet laser. It's wavelength is around 470nm and it's

only

7mw:
http://cgi.ebay.com/JDS-UNIPHASE-2214-VIOLET-ARGON-LASER-HEAD-

cyionics-

dpss_W0QQitemZ200036796821QQihZ010QQcategoryZ53141QQssPageNameZWDVWQQr
dZ1QQcmdZViewItem
Thought you might like to know.
By the way,I see you've been confused by the third 'leg' on your laser
diode ; that's a pin
for an internal photodiode to monitor the power output so you can use

a

feedback to keep
the output steady. Many laser driver I.C.s have a complimentary pin

for

this function.
Most very high output diodes don't have one.-Keith

_________________________________________________________________
House hunt online now!
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%2Eau%2Fcgi%2Dbin%2Frsearch%3Fa%3Dbhp%26t%3Dres%26cu%3DMSN&_t=758874163&_r
=HM_EndText_Oct06&_m=EXT



Don't forget to put yourself on the map!
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Yahoo! Groups Links

Hi Keith,

Yeah, I figured they could be over-driven. Hopefully I can come up with a
part number and data sheet that will tell me how to feed it.

Alan KM6VV

Behalf Of keith3125

The other thing you have to keep in mind is a laser has a threshold
voltage and current. So
you also have to find these out when you get a 'number' on the part and
spec it out.his is
not something one guesses at. Too much current and 'pop' it goes.-Keith

Behalf Of keith3125

The other thing you have to keep in mind is a laser has a threshold
voltage and current. So
you also have to find these out when you get a 'number' on the part and
spec it out.his is
not something one guesses at. Too much current and 'pop' it goes.-Keith

Hi Keith,

That's about what I was thinking; I'll have to determine what power and feed
rates will give the exposure needed. Having too much sensitivity? I would
have guessed not enough, resulting in intolerably long times to expose
"cuts", and thus make the process unacceptable (even for a hobby use).

The optics, even just a simple lens might prove to be an obstacle. No
simple way to "focus" the UV! And UV focus point would be different then
visible light focus.

I'll see if I can get the diode out of its mounting, and find some part
numbers. I'd like to light it up, if even with a minimal amount of current.


Oh yes, it would appear that a UV shield of some sort would be needed on the
mill, or work under a bug (yellow) lamp. I'm already working in a Plexiglas
box, so that shouldn't be too much of a problem.

You mention liquid resists; I was thinking that it's really not that much of
a problem to laminate a resist on the board (or anything else) myself. It
would make it quite flexible. "Pocket" laminators at Staples are
reasonable, and I'm guessing a useful laminator could be made from laser
printer parts.

A lot of details to work out! It's still mostly a dream at this point.

Alan KM6VV

-----Original Message-----
From: pcb-gcode@... [mailto:pcb-gcode@...] On
Behalf Of keith3125
Sent: Friday, October 20, 2006 8:44 AM
To: pcb-gcode@...
Subject: [pcb-gcode] Re: new to group/cutters, Lasers, LEDs and
Fluorescent tubes for PCBs

The coherent nature of the laser is going to give you more 'power out' and
much more
easily collimated( and don't forget the die chip of an L.E.D. has a
limiting diameter for
collimation) but you would need to know the exposure necessary and
calculate necessary
power versus time versus proximity to light output( distance is part of
the function of the
light received) anyway. If the emulsion is too sensitive(like the liquid
emulsion they sell)
then you'll have to keep out all other UV like from the sun(a moving
aperature possibly).

The third leg of the diode can be ignored if you calculate the exact
current you need and
then drive it with a regulated source. I've done it. You'd have to find a
number on the
particular diode you have to figure out the pinout.-Keith

-----Original Message-----
From: pcb-gcode@... [mailto:pcb-gcode@...] On
Behalf Of keith3125
Sent: Friday, October 20, 2006 8:44 AM
To: pcb-gcode@...
Subject: [pcb-gcode] Re: new to group/cutters, Lasers, LEDs and
Fluorescent tubes for PCBs

The coherent nature of the laser is going to give you more 'power out' and
much more
easily collimated( and don't forget the die chip of an L.E.D. has a
limiting diameter for
collimation) but you would need to know the exposure necessary and
calculate necessary
power versus time versus proximity to light output( distance is part of
the function of the
light received) anyway. If the emulsion is too sensitive(like the liquid
emulsion they sell)
then you'll have to keep out all other UV like from the sun(a moving
aperature possibly).

The third leg of the diode can be ignored if you calculate the exact
current you need and
then drive it with a regulated source. I've done it. You'd have to find a
number on the
particular diode you have to figure out the pinout.-Keith

Behalf Of keith3125

Here's a cheap violet laser. It's wavelength is around 470nm and it's only
7mw:
http://cgi.ebay.com/JDS-UNIPHASE-2214-VIOLET-ARGON-LASER-HEAD-cyionics-
dpss_W0QQitemZ200036796821QQihZ010QQcategoryZ53141QQssPageNameZWDVWQQr
dZ1QQcmdZViewItem
Thought you might like to know.
By the way,I see you've been confused by the third 'leg' on your laser
diode ; that's a pin
for an internal photodiode to monitor the power output so you can use a
feedback to keep
the output steady. Many laser driver I.C.s have a complimentary pin for
this function.
Most very high output diodes don't have one.-Keith