LIQUID-COOLED LASER AMPLIFIER HEAD

Abstract

The invention relates to a laser amplifier head comprising plates of a laser active medium which are placed inside a housing which has an inlet port and an outlet port, as well as a window that allows a laser beam to pass through the plates, characterized in that it comprises: a cooling means comprising: o a cooling circuit connected to the housing and suited to the circulation of a cooling liquid; o a cooling duct, inside the housing, in contact with the active medium, through which the cooling liquid flows, allowing an exchange of heat between the latter and the plates, o a regulating means able to regulate a temperature of the cooling liquid such that a thermo-optical coefficient dn / dT of the cooling liquid satisfies the following condition: (I) where AT represents the difference in temperature between the cooling liquid and the plates of the active medium, ∑φH represents the sum of the hydraulic diameters of the cooling duct, and λ0 represents the wavelength of the beam in a vacuum.

Claims

CLAIMS Laser amplifier head (1) comprising at least one plate of a solid-state laser active medium (2) disposed in a housing (4) having an inlet port (40) and an outlet port (42) for a coolant (6), and at least one window (41) allowing a laser beam to be amplified (80) to pass through the plate(s) of laser active medium (2), characterized in that it also comprises: - a cooling means (10) for the active medium (2), the cooling means (10) comprising a cooling circuit (100) connected to the housing (4) via the inlet port (40) and the outlet port (42), the cooling circuit being adapted to circulate the coolant (6) in turbulent flow, the cooling means (10) comprising at least one cooling channel (101) disposed in the housing (4), connecting the inlet port (40) and the outlet port (42), and in contact with the active medium (2), in which the coolant flows so as to allow heat exchange between the active medium (2) and the coolant (6),the cooling means (10) also comprising a means for regulating the temperature (102) of the coolant (6) capable of regulating a temperature of the coolant (6) such that a thermo-optical coefficient dn / dT of the coolant (6) satisfies the following condition:, And preferably where JT represents the temperature difference between the coolant (6) and at least one plate of the active medium (2), J) p H represents the sum of the hydraulic diameters of the cooling channels (101) traversed by the laser beam (80) and  orepresents the wavelength of the laser beam (80) in a vacuum. Laser amplifier head (1) according to claim 1, wherein the means for regulating the temperature of the coolant (10) is capable of canceling the thermo-optical coefficient of the coolant (6). Laser amplifier head (1) according to claim 1 or 2, wherein the cooling means (10) comprises a means for regulating the flow rate (104) of the coolant (6) capable of regulating the Reynolds number of the coolant (6) so as to be greater than 2300. A laser amplifier head (1) according to any one of the preceding claims, wherein the coolant (6) is water. A laser amplifier head (1) according to any one of the preceding claims, wherein the coolant (6) is a mixture of at least two chemical substances and has a thermo-optical coefficient different from that of each of these at least two substances. A laser amplifier head (1) according to any one of claims 4 or 5, wherein the means (10) for regulating the temperature of the coolant (6) is capable of regulating the temperature of the coolant (6) between 0°C and 10°C.A laser amplifier head (1) according to claim 6, wherein the cooling means (10) comprises: a storage device (105) for the coolant (6), said coolant (6) being in equilibrium between its liquid and solid phases, and a pumping device (106) for the coolant (6) capable of drawing the liquid phase of the coolant (6) from the storage device (105). A laser amplifier head (1) according to any one of the preceding claims, wherein the coolant (6) is in contact with a plate of the plurality of plates of the active medium (2).A laser amplifier head (1) according to any one of the preceding claims, comprising a contact window (411), a hygroscopic insulation volume (43), and an eccentric window (412), the contact window (411) having one face bearing against the housing (4), the contact window (411), the hygroscopic insulation volume (43), and the eccentric window (412) being successively aligned along the laser beam (80). A laser amplifier head (1) according to any one of the preceding claims, comprising at least one sensor (110, 111, 112, 113) positioned along the cooling circuit (100) so as to measure the flow rate and / or temperature of the coolant (6) in order to deduce the Reynolds number of the coolant (6) in at least one cooling channel (101) of the housing (4).laser amplifier head (1) according to any one of the preceding claims, comprising a physico-chemical filtration and biological purification system (108) for the coolant (6).

12. Laser amplifier head (1) according to any one of the preceding claims, comprising a system for verifying the spatial quality (12) of an amplified laser beam (82) at the output of the laser amplifier head (1).