Laser pumped by photoionization generated, electrically heated plasma

Claim 2

A laser comprising a volume of gas having a lasing constituent, a light source arranged to emit light having an effective photon energy spectrum below the ionization potential of said lasing constituent and chosen to photoionize at least a constituent of said gas predominantly by a multiple step process involving absorption of successive photons at least the first of which has a photon energy less than the ionization potential of said constituent being ionized, for photoionizing said gas to produce a plasma, and an electric field source for applying to said gas a sustaining voltage below the avalanche breakdown voltage of said gas, but high enough to heat said plasma to an energy level sufficient to effectively raise said lasing constituent to its lasing level.

Claim 3

The laser of claim 1 wherein said volume of gas includes a seed gas distributed through said lasing constituent and having an ionization potential below that of said lasing constituent.

Claim 4

The laser of claim 2 wherein said seed gas is at a lower partial pressure than said lasing constituent.

Claim 5

The laser of claim 2 wherein said spectrum has a distribution predetermined to photoionize said seed gas predominantly by a multiple step process involving absorption of successive photons at least the first of which has a photon energy less than the ionization potential of said seed gas.

Claim 6

The laser of claim 2 wherein the energy levels of said seed gas all differ from the upper lasing level of said lasing constituent by more than the average thermal energy of a molecule of said gas, whereby quenching of said upper lasing level is avoided.

Claim 7

The laser of claim 2 wherein said seed gas is tri-n-propyl amine.

Claim 8

A CO2-N2-He laser according to claim 6.

Claim 9

The laser of claim 1 wherein said constituent being ionized is said lasing constituent.

Claim 10

The laser of claim 8 wherein said multiple step process includes a first step utilizing a weakly allowed transition.

Claim 11

The laser of claim 1 including opposing mirrors in said volume for operation in an oscillating mode.

Claim 12

The laser of claim 1 wherein said gas is at least at atmospheric pressure.

Claim 13

The laser of claim 1 further comprising means for collimating the light from said source, and mirrors for directing and redirecting the collimated light in said volume to increase the utilization of the penetration depth of the plasma-producing photons.

Claim 16

The method of claim 13 further comprising maintaining in said lasing constituent a seed gas having an ionization potential below that of said lasing constituent.

Claim 17

The method of claim 13 further comprising establishing the distribution of said Spectrum to photoionize said seed gas by a multiple step process involving absorption of successive photons at least the first of which has a photon energy less than the ionization potential of said seed gas.

Claim 18

The method of claim 14 wherein the energy levels of said seed gas all differ from the upper lasing level of said lasing constituent by more than the average thermal energy of a molecule of said gas, whereby quenching of said upper lasing level is avoided.

Claim 19

The method of claim 14 wherein said seed gas is tri-n-propyl amine.

Claim 20

The method of claim 17 applied to a CO2-N2-He laser.

Claim 21

The method of claim 13 wherein said constituent being ionized is said lasing constituent.

Claim 22

The method of claim 19 wherein said multiple step process includes a first step utilizing a weakly allowed transition.

Claim 23

The method of claim 13 wherein said laser is caused to operate in an oscillating mode.

Claim 24

The method of claim 13 further comprising maintaining said gas at least at atmospheric pressure.

Claim 25

The method of claim 13 further comprising collimating said light and directing and redirecting it through said gas to increase the utilization of the penetration depth of the plasma-producing photons.

Claim 26

A laser comprising a volume of gas having a lasing constituent, said volume being at least 20 liters, said gas having a total pressure of at least 1 atmosphere, a source of light to pass through said volume, said light having a photon energy spectrum lying below the ionization potential of said lasing constituent and avoiding any of the strong absorption bands of said gas, so as to produce a mean photon penetration of at least of the order of a meter, and chosen to photoionize at least a constituent of said gas predominantly by a multiple step process involving absorption of successive photons at least the first of which has a photon energy less than the ionization potential of said constituent being ionized, for photoionizing said gas to produce a plasma, and an electric field source for applying to said gas a sustaining voltage below the avalanche breakdown voltage of said gas, but high enough to heat said plasma to an energy level sufficient to effectively raise said lasing constituent to its lasing level.

Claim 27

A laser comprising a volume of gas having a lasing constituent, said volume being at least 20 liters, said gas having a total pressure of at least 1 atmosphere, a source of light to pass through said volume, said light having a photon energy spectrum lying below the ionization potential of said lasing constituent and avoiding any of the strong absorption bands of said gas, so as to produce a mean photon penetration of at least of the order of a meter, and chosen to photoionize at least a constituent of said gas predominantly by a multiple step process involving absorption of successive photons at least the first of which has a photon energy less than the ionization potential of said constituent being ionized, for photoionizing said gas to produce a plasma, and an electric field source for applying to said gas a sustaining voltage below the avalanche breakdown voltage of said gas, but high enough to heat said plasma to an energy level sufficient to effectively raise said lasing constituent to its lasing level.