Your post about laser ignition forced me to look a little deeper:

http://www.liv.ac.uk/researchintelli...erignition.htm

On Jul 23, 9:46*am, NotNow wrote:
Your post about laser ignition forced me to look a little deeper:

http://www.liv.ac.uk/researchintelli...erignition.htm

Being an optics guy, I see nothing too surprising about this, be
optimistic but do not be too optimistic. First, bending optical
fibers does lead to large losses. You normally do not notice this
because you are not dealing with high power levels but at such high
levels, it is a real problem. Next, consider what happens when your
lens gets soot on it. It absorbs some of the laser power and soon
gets very hot and focuses poorly. I am sure this is solvable with
some work.
I'd suggest an optic called an axicon that focuses light onto a line
centered on axis rather than to a spot. This will make the combustion
more volumetric instead of originating from a point.
Optical fibers are actually a sorta poor way to do this due to
losses. What they ought to use is hollow metal light guides with an
internal reflecting surface. These would be mounted in the same way
as fuel injection lines. If you truly want to be bored, I can give
you all the details on how hollow light guides differ from optical
fiber.
I am sure somebody has done work on piezo-ignition but I have never
seen it. You'd think it could be set to fire at some specific level
of compression. Piezo crystals emit a voltage when a rapid pressure is
applied, they are the things used in cig lighters that do not have
"flints".
Interesting.

"Frogwatch" wrote in message
...


I am sure somebody has done work on piezo-ignition but I have never
seen it. You'd think it could be set to fire at some specific level
of compression. Piezo crystals emit a voltage when a rapid pressure is
applied, they are the things used in cig lighters that do not have
"flints".


Just think of all the people swearing at their cars like they do now at
their 2 year old gas grills.

Eisboch

On Thu, 23 Jul 2009 11:42:28 -0400, "Eisboch"
wrote:


"Frogwatch" wrote in message
...


I am sure somebody has done work on piezo-ignition but I have never
seen it. You'd think it could be set to fire at some specific level
of compression. Piezo crystals emit a voltage when a rapid pressure is
applied, they are the things used in cig lighters that do not have
"flints".


Just think of all the people swearing at their cars like they do now at
their 2 year old gas grills.

Eisboch

Two years? Hell, the one in my grill made it through a whole month,
almost.
--

John H

On Jul 23, 11:55*am, John Again wrote:
On Thu, 23 Jul 2009 11:42:28 -0400, "Eisboch"
wrote:





"Frogwatch" wrote in message
....

I am sure somebody has done work on piezo-ignition but I have never
seen it. *You'd think it could be set to fire at some specific level
of compression. Piezo crystals emit a voltage when a rapid pressure is
applied, they are the things used in cig lighters that do not have
"flints".

Just think of all the people swearing at their cars like they do now at
their 2 year old gas grills.

Eisboch

Two years? Hell, the one in my grill made it through a whole month,
almost.
--

John H

I use charcoal so I did not know this was a problem.

Frogwatch wrote:
On Jul 23, 11:55 am, John Again wrote:
On Thu, 23 Jul 2009 11:42:28 -0400, "Eisboch"
wrote:





"Frogwatch" wrote in message
...
I am sure somebody has done work on piezo-ignition but I have never
seen it. You'd think it could be set to fire at some specific level
of compression. Piezo crystals emit a voltage when a rapid pressure is
applied, they are the things used in cig lighters that do not have
"flints".
Just think of all the people swearing at their cars like they do now at
their 2 year old gas grills.
Eisboch
Two years? Hell, the one in my grill made it through a whole month,
almost.
--

John H

I use charcoal so I did not know this was a problem.

Yep! If I wanted to cook with gas, why would I go outside to do it?

"John Again" wrote in message
...
On Thu, 23 Jul 2009 11:42:28 -0400, "Eisboch"
wrote:


"Frogwatch" wrote in message
...


I am sure somebody has done work on piezo-ignition but I have never
seen it. You'd think it could be set to fire at some specific level
of compression. Piezo crystals emit a voltage when a rapid pressure is
applied, they are the things used in cig lighters that do not have
"flints".


Just think of all the people swearing at their cars like they do now at
their 2 year old gas grills.

Eisboch

Two years? Hell, the one in my grill made it through a whole month,
almost.
--

John H

Read the manual....mine is still working after 7 or 8 years.

On Thu, 23 Jul 2009 16:44:22 -0300, "Don White"
wrote:


"John Again" wrote in message
.. .
On Thu, 23 Jul 2009 11:42:28 -0400, "Eisboch"
wrote:


"Frogwatch" wrote in message
...


I am sure somebody has done work on piezo-ignition but I have never
seen it. You'd think it could be set to fire at some specific level
of compression. Piezo crystals emit a voltage when a rapid pressure is
applied, they are the things used in cig lighters that do not have
"flints".


Just think of all the people swearing at their cars like they do now at
their 2 year old gas grills.

Eisboch

Two years? Hell, the one in my grill made it through a whole month,
almost.
--

John H

Read the manual....mine is still working after 7 or 8 years.


Wow. You're the man all right!

Great job. See, I told everyone you were just pretending.
--

John H

"Don White" wrote in message
...

"John Again" wrote in message
...
On Thu, 23 Jul 2009 11:42:28 -0400, "Eisboch"
wrote:


"Frogwatch" wrote in message
...


I am sure somebody has done work on piezo-ignition but I have never
seen it. You'd think it could be set to fire at some specific level
of compression. Piezo crystals emit a voltage when a rapid pressure is
applied, they are the things used in cig lighters that do not have
"flints".


Just think of all the people swearing at their cars like they do now at
their 2 year old gas grills.

Eisboch

Two years? Hell, the one in my grill made it through a whole month,
almost.
--

John H

Read the manual....mine is still working after 7 or 8 years.


Yeah, but you only have, What?, a 5 day bbq season?

On Thu, 23 Jul 2009 11:42:28 -0400, "Eisboch"
wrote:


"Frogwatch" wrote in message
...


I am sure somebody has done work on piezo-ignition but I have never
seen it.
A lawn mower was featured in Popular Mechanics about forty years ago.

You'd think it could be set to fire at some specific level of compression.
Piezo crystals emit a voltage when a rapid pressure is
applied, they are the things used in cig lighters that do not have
"flints".

Many of the throwaway lighters are in fact, refillable, and in many
cases, see through, so you know when. Too bad the sparkers fail early
and often. Always just after you put in a full four grams of butane.

Casady