1. An apparatus, comprising:
a coolant delivery system that creates a layer of coolant over a target area, wherein the target area comprises at least one carious region; and
a laser generator that directs a laser beam to the target area to ablate the at least one carious region;
wherein the laser generator operates substantially simultaneously with the coolant delivery system to direct the laser beam through the layer of coolant to the target area;
wherein the layer of coolant cools the target area to reduce thermal damage from the laser beam.
2. The apparatus of claim 1, wherein the laser generator comprises an infrared laser generator;
wherein the infrared laser generator creates the laser beam with a wavelength approximately between two and five microns.
3. The apparatus of claim 2, wherein the infrared laser generator comprises one of a Er:YAG laser, a CTE:YAG laser, a Er:YALO3 laser, a CTH:YAG laser, or a Ho:YAG laser.
4. The apparatus of claim 1, wherein the laser beam comprises a pulsed laser beam with a repetition rate approximately between one and 10,000 pulses per second.
5. The apparatus of claim 4, wherein the pulsed laser beam comprises an energy level approximately between 0.01 millijoules per pulse and five joules per pulse.
6. The apparatus of claim 1, wherein the laser generator creates the laser beam with a predetermined fluence level to selectively ablate the at least one carious region with reduced thermal damage to the target area.
7. The apparatus of claim 6, wherein the predetermined fluence level is approximately between 0.05 and 10.0 Jcm2.
8. The apparatus of claim 6, wherein the laser generator selects the predetermined fluence level based on an absorption coefficient of the at least one carious region.
9. The apparatus of claim 1, wherein the layer of coolant comprises a thickness approximately between 0.01 millimeters and 3.0 millimeters.
10. The apparatus of claim 1, wherein the coolant delivery system begins delivery of the layer of coolant before a start of the laser beam by the laser generator.
11. The apparatus of claim 1, wherein the coolant delivery system is configured to provide a continuous flow, irrigation, stream, or pool of the coolant over the target area.
12. The apparatus of claim 1, wherein the coolant delivery system comprises an indirect aim of a spray of the coolant at the target area to reduce attenuation of the laser beam through the spray of the coolant.
13. The apparatus of claim 12, wherein the indirect aim of the spray of the coolant, a momentum of the spray of the coolant, and a surface tension of the coolant cooperate to form the layer of coolant over the target area.
14. The apparatus of claim 1, wherein the coolant comprises water.
15. An apparatus, comprising:
a coolant delivery system;
a laser generator; and
a handpiece coupled with the coolant delivery system to receive a supply of coolant, and configured to create a layer of coolant over a target area, wherein the target area comprises at least one carious region;
wherein the handpiece comprises an optical fiber that is optically coupled with the laser generator to receive a laser beam from the laser generator and direct the laser beam through the layer of coolant to the target area to ablate the at least one carious region;
wherein the handpiece substantially simultaneously creates the layer of coolant over the target area and directs the laser beam through the layer of coolant to the target area to ablate the at least one carious region;
wherein the layer of coolant cools the target area to reduce thermal damage from the laser beam.
16. The apparatus of claim 14, wherein the laser generator comprises an infrared laser generator;
wherein the infrared laser generator creates the laser beam with a predetermined fluence level approximately between 0.05 and 10.0 Jcm2.
17. The apparatus of claim 14, wherein the handpiece is configured to create the layer of coolant with a thickness approximately between 0.01 millimeters and 3.0 millimeters.
18. The apparatus of claim 16, wherein the handpiece is configured to create the layer of coolant as a continuous flow of coolant over the target area during operation of the laser beam.
19. The apparatus of claim 14, further comprising:
a suction system that removes excess coolant from the target area.
20. The apparatus of claim 1, wherein the coolant comprises water.
21. A method, comprising the steps of:
creating a pool of coolant over a target area for cooling of the target area, wherein the target area comprises at least one carious region; and
substantially simultaneously directing an infrared laser beam through the pool of coolant to the at least one carious region to ablate the at least one carious region.
22. The method of claim 19, wherein the step of creating the pool of coolant comprises the step of:
indirectly aiming a spray of the coolant at the target area to reduce attenuation of the infrared laser beam through the spray of the coolant.
23. An apparatus, comprising:
means for creating a pool of coolant over a target area for cooling of the target area, wherein the target area comprises at least one carious region; and
means for substantially simultaneously directing an infrared laser beam through the pool of coolant to the at least one carious region to ablate the at least one carious region.
24. The apparatus of claim 23, wherein the means for creating the pool of coolant comprises:
means for indirectly aiming a spray of the coolant at the target area to reduce attenuation of the infrared laser beam through the spray of the coolant.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A process of producing polyesters having a stable intrinsic viscosity by using a polycondensation reaction apparatus having one or more polycondensation reaction vessels provided with one or more sets of an ejector, an upstream condenser placed between the polycondensation reaction vessel and the ejector, a condenser placed in the downstream portion of the ejector, a barometric leg, and one or more hot well tanks connected to the condenser via the barometric leg, wherein the upstream condenser is equipped with a collection tank for collecting a condensate obtained from condensing a vaporous composition obtained from the polycondensation reaction vessel, and
including driving the ejector by a vapor composed mainly of 1,4-butanediol, condensing the vapor composed mainly of 1,4-butanediol as discharged from the ejector in the condenser placed in the downstream portion of the ejector, and making the reactor in a reduced pressure state to undergo polycondensation reaction, the process being characterized in that:
water contained in a sealing liquid in at least one hot well tank is maintained at a concentration of not more than 3% by weight; and
tetrahydrofuran contained in a sealing liquid in at least one hot well tank is maintained at a concentration of not more than 4% by weight to thereby produce polyesters having a stable intrinsic viscosity.
2. The process of producing polyesters according to claim 1, wherein the polycondensation reaction apparatus has one or more polycondensation reaction vessels each provided with two or more sets of an ejector, a condenser placed in the downstream portion of the ejector, and a barometric leg and has two or more hot well tanks,
the concentration of tetrahydrofuran contained in a sealing liquid in at least one hot well tank being not more than 4% by weight.
3. The process of producing polyesters according to claim 1, wherein the polycondensation reaction apparatus has two or more polycondensation reaction vessels each provided with one or more sets of an ejector, a condenser placed in the downstream portion of the ejector, and a barometric leg and has two or more hot well tanks,
the concentration of tetrahydrofuran contained in a sealing liquid in at least one hot well tank being not more than 4% by weight.
4. The process of producing polyesters according to claim 1, wherein the polycondensation reaction apparatus has two or more polycondensation reaction vessels each provided with two or more sets of an ejector, a condenser placed in the downstream portion of the ejector, and a barometric leg and has two or more hot well tanks,
the concentration of tetrahydrofuran contained in a sealing liquid in at least one hot well tank being not more than 4% by weight.
5. The process of producing polyesters according to claim 1, wherein a liquid having a tetrahydrofuran concentration of not more than 1% by weight is fed into at least one hot well tank, and the concentration of tetrahydrofuran contained in a sealing liquid in said hot well tank is adjusted at not more than 4% by weight.
6. The process of producing polyesters according to claim 5, wherein a sealing liquid in at least one hot well tank is discharged, tetrahydrofuran is separated and removed from a part or the whole of said liquid to obtain a liquid having a tetrahydrofuran concentration of not more than 1% by weight, and a part or the whole of said liquid is fed into at least one hot well tank.
7. The process of producing polyesters according to claim 1, wherein a sealing liquid in at least one hot well tank is discharged, a part or the wholes of said liquid is fed into a boiler for generation of a 1,4-butanediol vapor to form a 1,4butanediol vapor, and this 1,4-butanediol vapor is used as a vapor for ejector driving.
8. The process of producing polyesters according to claim 1, wherein the polyester is polybutylene terephthalate.
9. A process of producing a polyester having a stable intrinsic viscosity with a polycondensation reaction apparatus,
wherein said polycondensation reaction apparatus comprises one or more polycondensation reactors each operating at a stable reduced pressure and independently equipped with, in successive order, one or more of each of the following: upstream condensers equipped with a collection tank for collecting a condensate obtained from condensing a vaporous composition obtained from the polycondensation reactor; vapor driven ejectors; downstream condensers; barometric legs; and hot well tanks comprising a sealing liquid obtained from said downstream condensers via said barometric legs, and
wherein said process comprises:
driving said one or more vapor driven ejectors with a vapor predominantly comprising 1,4-butanediol;
maintaining a water concentration of not more than 3 wt. % within said sealing liquid of at least one of said one or more hot well tanks; and
maintaining a tetrahydrofuran concentration of less than or equal to 4 wt. % within said sealing liquid of at least one of said one or more hot well tanks to thereby produce polyesters having a stable intrinsic viscosity.
10. The process of producing a polyester according to claim 9,
wherein said one or more polycondensation reactors are each independently further equipped with, downstream of said one or more hot well tanks comprising said sealing liquid, one or more distillation columns producing a 1,4-butanediol distillate, and
wherein said process further comprises feeding said 1,4-butanediol distillate, which comprises tetrahydrofuran at a concentration of less than or equal to 2 wt. %, obtained from said one or more distillation columns into at least one of said one or more hot well tanks, thereby maintaining a tetrahydrofuran concentration of less than or equal to 4 wt. % within said sealing liquid of at least one of said one or more hot well tanks.
11. The process of producing a polyester according to claim 9,
wherein said one or more polycondensation reactors are each independently further equipped with, downstream of said one or more hot well tanks comprising said sealing liquid, one or more boilers,
wherein said process further comprises feeding said sealing liquid of at least one of said hot well tanks into said one or more boilers thereby generating a 1,4-butanediol vapor for driving said one or more vapor driven ejectors.
12. The process of producing a polyester according to claim 9, wherein said stable reduced pressure is less than or equal to 27 kPa.
13. The process of producing a polyester according to claim 9, wherein each of said one or more downstream condensers have an identical or different pressure of from 1.6 kPa to 15 kPa.
14. The process of producing a polyester according to claim 10, wherein said 1,4-butanediol distillate comprises tetrahydrofuran at a concentration of less than or equal to 1 wt. %.
15. The process of producing a polyester according to claim 9, wherein said sealing liquid within at least one of said hot well tanks comprises tetrahydrofuran maintained at a concentration of less than or equal to 3 wt. %.
16. The process of producing a polyester according to claim 9, wherein said sealing liquid within at least one of said hot well tanks comprises tetrahydrofuran maintained at a concentration of less than or equal to 1.5 wt. %.
17. The process of producing a polyester according to claim 9, wherein said sealing liquid within at least one of said hot well tanks comprises tetrahydrofuran maintained at a concentration of less than or equal to 1 wt. %.
18. The process of producing a polyester according to claim 9, wherein said polyester comprises a dicarboxylic acid unit selected from an aromatic dicarboxylic acid unit, an alicyclic dicarboxylic acid unit, and an aliphatic dicarboxylic acid unit,
wherein said aromatic dicarboxylic acid unit is selected from the group consisting of terephthalic acid, isophthalic acid, 4,4\u2032-diphenyldicarboxylic acid, 4,4\u2032-diphenyl ether dicarboxylic acid, 4,4\u2032-benzophenonedicarboxylic acid, 4,4\u2032-diphenoxyethanedicarboxylic acid, 4,4\u2032-diphenylsulfonedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid,
wherein said alicyclic dicarboxylic acid unit is selected from the group consisting of 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4- cyclohexanedicarboxylic acid, and
wherein said aliphatic dicarboxylic acid unit is selected from the group consisting of malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.
19. The process of producing a polyester according to claim 9, wherein said polyester comprises a 1,4-butanediol unit.
20. The process of producing a polyester according to claim 9, wherein said polyester comprises a 1,4-butanediol unit, and a dicarboxylic acid unit selected from the group consisting of terephthalic acid, isophthalic acid, succinic acid, and adipic acid.