Lasers Question

Johnny1a wrote:
> On Oct 12, 3:20 pm, "Luke Campbell" <lwc....DeleteThis@gmail.com> wrote:
>
> What is the effect of that kind of energy density on liquids? That is,
> could we produce protection by placing a layer of flowing liquid
> between target and gunner, so that new liquid flows steadily into the
> intersection area even as the pulses vaporize what's there?

The energy density is high enough that liquid matter behaves
essentially like solid matter on the time scales appropriate for light
absorption. Now as for the response of the material after that time -
the design I had in mind of a burst of pulses delivered within about a
millisecond would create an expanding cavity through the liquid, with
the remainder of the burst traveling through air or vapor rather than
liquid. The cavity would eventually recollapse, but on a longer
timescale than the duration of the burst. In this sense, the liquid
would provide some protection (it absorbs some of the leading pulses),
but less than a rigid, tough material. It would, of course, "heal"
itself in a fairly short time so that a second burst would have to blow
through it again.

Luke
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Johnny1a wrote:
> On Oct 12, 3:20 pm, "Luke Campbell" <lwc....DeleteThis@gmail.com> wrote:
>
> What is the effect of that kind of energy density on liquids? That is,
> could we produce protection by placing a layer of flowing liquid
> between target and gunner, so that new liquid flows steadily into the
> intersection area even as the pulses vaporize what's there?

The energy density is high enough that liquid matter behaves
essentially like solid matter on the time scales appropriate for light
absorption. Now as for the response of the material after that time -
the design I had in mind of a burst of pulses delivered within about a
millisecond would create an expanding cavity through the liquid, with
the remainder of the burst traveling through air or vapor rather than
liquid. The cavity would eventually recollapse, but on a longer
timescale than the duration of the burst. In this sense, the liquid
would provide some protection (it absorbs some of the leading pulses),
but less than a rigid, tough material. It would, of course, "heal"
itself in a fairly short time so that a second burst would have to blow
through it again.

Luke
 >> Stay informed about: Lasers Question 

Johnny1a wrote:
> On Oct 12, 3:20 pm, "Luke Campbell" <lwc....DeleteThis@gmail.com> wrote:
>
> What is the effect of that kind of energy density on liquids? That is,
> could we produce protection by placing a layer of flowing liquid
> between target and gunner, so that new liquid flows steadily into the
> intersection area even as the pulses vaporize what's there?

The energy density is high enough that liquid matter behaves
essentially like solid matter on the time scales appropriate for light
absorption. Now as for the response of the material after that time -
the design I had in mind of a burst of pulses delivered within about a
millisecond would create an expanding cavity through the liquid, with
the remainder of the burst traveling through air or vapor rather than
liquid. The cavity would eventually recollapse, but on a longer
timescale than the duration of the burst. In this sense, the liquid
would provide some protection (it absorbs some of the leading pulses),
but less than a rigid, tough material. It would, of course, "heal"
itself in a fairly short time so that a second burst would have to blow
through it again.

Luke
 >> Stay informed about: Lasers Question 

Johnny1a wrote:
> On Oct 12, 3:20 pm, "Luke Campbell" <lwc... DeleteThis @gmail.com> wrote:
>
> What is the effect of that kind of energy density on liquids? That is,
> could we produce protection by placing a layer of flowing liquid
> between target and gunner, so that new liquid flows steadily into the
> intersection area even as the pulses vaporize what's there?

The energy density is high enough that liquid matter behaves
essentially like solid matter on the time scales appropriate for light
absorption. Now as for the response of the material after that time -
the design I had in mind of a burst of pulses delivered within about a
millisecond would create an expanding cavity through the liquid, with
the remainder of the burst traveling through air or vapor rather than
liquid. The cavity would eventually recollapse, but on a longer
timescale than the duration of the burst. In this sense, the liquid
would provide some protection (it absorbs some of the leading pulses),
but less than a rigid, tough material. It would, of course, "heal"
itself in a fairly short time so that a second burst would have to blow
through it again.

Luke
 >> Stay informed about: Lasers Question 

Johnny1a wrote:
> On Oct 12, 3:20 pm, "Luke Campbell" <lwc... RemoveThis @gmail.com> wrote:
>
> What is the effect of that kind of energy density on liquids? That is,
> could we produce protection by placing a layer of flowing liquid
> between target and gunner, so that new liquid flows steadily into the
> intersection area even as the pulses vaporize what's there?

The energy density is high enough that liquid matter behaves
essentially like solid matter on the time scales appropriate for light
absorption. Now as for the response of the material after that time -
the design I had in mind of a burst of pulses delivered within about a
millisecond would create an expanding cavity through the liquid, with
the remainder of the burst traveling through air or vapor rather than
liquid. The cavity would eventually recollapse, but on a longer
timescale than the duration of the burst. In this sense, the liquid
would provide some protection (it absorbs some of the leading pulses),
but less than a rigid, tough material. It would, of course, "heal"
itself in a fairly short time so that a second burst would have to blow
through it again.

Luke
 >> Stay informed about: Lasers Question 

Johnny1a wrote:
> On Oct 12, 3:20 pm, "Luke Campbell" <lwc... RemoveThis @gmail.com> wrote:
>
> What is the effect of that kind of energy density on liquids? That is,
> could we produce protection by placing a layer of flowing liquid
> between target and gunner, so that new liquid flows steadily into the
> intersection area even as the pulses vaporize what's there?

The energy density is high enough that liquid matter behaves
essentially like solid matter on the time scales appropriate for light
absorption. Now as for the response of the material after that time -
the design I had in mind of a burst of pulses delivered within about a
millisecond would create an expanding cavity through the liquid, with
the remainder of the burst traveling through air or vapor rather than
liquid. The cavity would eventually recollapse, but on a longer
timescale than the duration of the burst. In this sense, the liquid
would provide some protection (it absorbs some of the leading pulses),
but less than a rigid, tough material. It would, of course, "heal"
itself in a fairly short time so that a second burst would have to blow
through it again.

Luke
 >> Stay informed about: Lasers Question 

Johnny1a wrote:
> On Oct 12, 3:20 pm, "Luke Campbell" <lwc....RemoveThis@gmail.com> wrote:
>
> What is the effect of that kind of energy density on liquids? That is,
> could we produce protection by placing a layer of flowing liquid
> between target and gunner, so that new liquid flows steadily into the
> intersection area even as the pulses vaporize what's there?

The energy density is high enough that liquid matter behaves
essentially like solid matter on the time scales appropriate for light
absorption. Now as for the response of the material after that time -
the design I had in mind of a burst of pulses delivered within about a
millisecond would create an expanding cavity through the liquid, with
the remainder of the burst traveling through air or vapor rather than
liquid. The cavity would eventually recollapse, but on a longer
timescale than the duration of the burst. In this sense, the liquid
would provide some protection (it absorbs some of the leading pulses),
but less than a rigid, tough material. It would, of course, "heal"
itself in a fairly short time so that a second burst would have to blow
through it again.

Luke
 >> Stay informed about: Lasers Question 

Johnny1a wrote:
> On Oct 12, 3:20 pm, "Luke Campbell" <lwc....RemoveThis@gmail.com> wrote:
>
> What is the effect of that kind of energy density on liquids? That is,
> could we produce protection by placing a layer of flowing liquid
> between target and gunner, so that new liquid flows steadily into the
> intersection area even as the pulses vaporize what's there?

The energy density is high enough that liquid matter behaves
essentially like solid matter on the time scales appropriate for light
absorption. Now as for the response of the material after that time -
the design I had in mind of a burst of pulses delivered within about a
millisecond would create an expanding cavity through the liquid, with
the remainder of the burst traveling through air or vapor rather than
liquid. The cavity would eventually recollapse, but on a longer
timescale than the duration of the burst. In this sense, the liquid
would provide some protection (it absorbs some of the leading pulses),
but less than a rigid, tough material. It would, of course, "heal"
itself in a fairly short time so that a second burst would have to blow
through it again.

Luke
 >> Stay informed about: Lasers Question 

Unobtrusive wrote:

> Simple enough; do without the rangefinder. If the laser can adjust it's
> range on the fly by moving mirrors & such, have the focus move quickly from
> just in front of your weapon to it's theoretical max-range and back again,
> therefore slicing neatly through everything between here and there.
> Invisible or not, you'll still hurt it if it can be hit.

This wastes a lot of energy. If you can kill a person with 1 kilojoule
of energy, you can pack a fair number of shots into a battery and with
reasonable rates of fire you don't need to worry about your weapon
overheating. Now if you need to focus 1 kilojoule (to ensure killing
your target) into each linear meter between the aperture of the laser
and the maximum range (say 500 meters) you use 500 times as much energy
and your weapon heats 500 times as fast. A fairly reasonable
extrapolation is that advanced weapons grade lasers could be about 50%
efficient - for every kJ of laser light, they generate one kJ of heat.
There is a technical term for devices that produce 500 kJ of heat
energy in about a millisecond - we call them bombs.

This is a rather inexact way of looking at things - for one thing, it
ignores depth of field effects (the furter away a beam is focused, the
longer the distance over which it stays focused. Likewise, when
focused at short distances, the beam will only stay in focus over a
very short distance), but it illustrates the problems with trying to
zap everything between the aperture and the maximum range.

Luke
 >> Stay informed about: Lasers Question 

Unobtrusive wrote:

> Simple enough; do without the rangefinder. If the laser can adjust it's
> range on the fly by moving mirrors & such, have the focus move quickly from
> just in front of your weapon to it's theoretical max-range and back again,
> therefore slicing neatly through everything between here and there.
> Invisible or not, you'll still hurt it if it can be hit.

This wastes a lot of energy. If you can kill a person with 1 kilojoule
of energy, you can pack a fair number of shots into a battery and with
reasonable rates of fire you don't need to worry about your weapon
overheating. Now if you need to focus 1 kilojoule (to ensure killing
your target) into each linear meter between the aperture of the laser
and the maximum range (say 500 meters) you use 500 times as much energy
and your weapon heats 500 times as fast. A fairly reasonable
extrapolation is that advanced weapons grade lasers could be about 50%
efficient - for every kJ of laser light, they generate one kJ of heat.
There is a technical term for devices that produce 500 kJ of heat
energy in about a millisecond - we call them bombs.

This is a rather inexact way of looking at things - for one thing, it
ignores depth of field effects (the furter away a beam is focused, the
longer the distance over which it stays focused. Likewise, when
focused at short distances, the beam will only stay in focus over a
very short distance), but it illustrates the problems with trying to
zap everything between the aperture and the maximum range.

Luke
 >> Stay informed about: Lasers Question 

Unobtrusive wrote:

> Simple enough; do without the rangefinder. If the laser can adjust it's
> range on the fly by moving mirrors & such, have the focus move quickly from
> just in front of your weapon to it's theoretical max-range and back again,
> therefore slicing neatly through everything between here and there.
> Invisible or not, you'll still hurt it if it can be hit.

This wastes a lot of energy. If you can kill a person with 1 kilojoule
of energy, you can pack a fair number of shots into a battery and with
reasonable rates of fire you don't need to worry about your weapon
overheating. Now if you need to focus 1 kilojoule (to ensure killing
your target) into each linear meter between the aperture of the laser
and the maximum range (say 500 meters) you use 500 times as much energy
and your weapon heats 500 times as fast. A fairly reasonable
extrapolation is that advanced weapons grade lasers could be about 50%
efficient - for every kJ of laser light, they generate one kJ of heat.
There is a technical term for devices that produce 500 kJ of heat
energy in about a millisecond - we call them bombs.

This is a rather inexact way of looking at things - for one thing, it
ignores depth of field effects (the furter away a beam is focused, the
longer the distance over which it stays focused. Likewise, when
focused at short distances, the beam will only stay in focus over a
very short distance), but it illustrates the problems with trying to
zap everything between the aperture and the maximum range.

Luke
 >> Stay informed about: Lasers Question 

Unobtrusive wrote:

> Simple enough; do without the rangefinder. If the laser can adjust it's
> range on the fly by moving mirrors & such, have the focus move quickly from
> just in front of your weapon to it's theoretical max-range and back again,
> therefore slicing neatly through everything between here and there.
> Invisible or not, you'll still hurt it if it can be hit.

This wastes a lot of energy. If you can kill a person with 1 kilojoule
of energy, you can pack a fair number of shots into a battery and with
reasonable rates of fire you don't need to worry about your weapon
overheating. Now if you need to focus 1 kilojoule (to ensure killing
your target) into each linear meter between the aperture of the laser
and the maximum range (say 500 meters) you use 500 times as much energy
and your weapon heats 500 times as fast. A fairly reasonable
extrapolation is that advanced weapons grade lasers could be about 50%
efficient - for every kJ of laser light, they generate one kJ of heat.
There is a technical term for devices that produce 500 kJ of heat
energy in about a millisecond - we call them bombs.

This is a rather inexact way of looking at things - for one thing, it
ignores depth of field effects (the furter away a beam is focused, the
longer the distance over which it stays focused. Likewise, when
focused at short distances, the beam will only stay in focus over a
very short distance), but it illustrates the problems with trying to
zap everything between the aperture and the maximum range.

Luke
 >> Stay informed about: Lasers Question 

Unobtrusive wrote:

> Simple enough; do without the rangefinder. If the laser can adjust it's
> range on the fly by moving mirrors & such, have the focus move quickly from
> just in front of your weapon to it's theoretical max-range and back again,
> therefore slicing neatly through everything between here and there.
> Invisible or not, you'll still hurt it if it can be hit.

This wastes a lot of energy. If you can kill a person with 1 kilojoule
of energy, you can pack a fair number of shots into a battery and with
reasonable rates of fire you don't need to worry about your weapon
overheating. Now if you need to focus 1 kilojoule (to ensure killing
your target) into each linear meter between the aperture of the laser
and the maximum range (say 500 meters) you use 500 times as much energy
and your weapon heats 500 times as fast. A fairly reasonable
extrapolation is that advanced weapons grade lasers could be about 50%
efficient - for every kJ of laser light, they generate one kJ of heat.
There is a technical term for devices that produce 500 kJ of heat
energy in about a millisecond - we call them bombs.

This is a rather inexact way of looking at things - for one thing, it
ignores depth of field effects (the furter away a beam is focused, the
longer the distance over which it stays focused. Likewise, when
focused at short distances, the beam will only stay in focus over a
very short distance), but it illustrates the problems with trying to
zap everything between the aperture and the maximum range.

Luke
 >> Stay informed about: Lasers Question