Laser cooling system and method

Abstract

A folded sheet is used as a basis for a fin array to cool laser modules. The folded sheet has flat portions that are connected in thermal contact with the laser module, and fins formed by interconnecting portions. This arrangement is highly convenient for assembly, inexpensive, and provides for highly effective heat exchange.

Description

FIELD OF THE INVENTION [0001] The present invention relates to lasers, more particularly to providing lasers with suitable cooling fins. BACKGROUND OF THE INVENTION [0002] Typical cooling of a laser utilizes cooling fin arrays coupled with fans to convect heat away from the laser. The fins are typically milled into the body of the laser housing or are part of an extruded heat sink that is bolted to the laser body. In either case the milling or extruding limits the size, pitch and shape of the resulting fins. In particular, heat transfer is largely dependent on the heat transfer surface area. When milling fins, the pitch of the fins, i.e. the number of fins per unit distance, is limited by the milling tool size. The extrusion process has limits on fin width, fin pitch and the fin width to length ratio. [0003]FIG. 1 illustrates a conventional laser package 100, having a laser module 110 with an associated laser beam 190 also being illustrated. The laser module 110 has a cooling face 1...

AI Technical Summary

Benefits of technology

[0006] Using a folded sheet as a basis for the cooling fins is not only highly convenient from an assembly point of view, and inexpensive, but also provides for highly effective heat exchange away from the laser module. First, the folded sheet can be attached to the laser module cooling face with a large area of good thermal contact via its flat portions. Second, the fins formed by the interconnecting portions of the sheet can present a high-drag to a fluid flow being forced past the fins by a fan or pump, thereby inducing significant turbulence which is an aid to carrying heat away from the fins. As a result a highly efficient heat exchanger can be provided in a small size.

[0010] In some embodiments the cooling fins extend in a plurality of strips arranged alongside each other such that the cooling fins in adjacent ones of the strips are offset from one another. This staggered fin design can further increase turbulent flow, thereby further increasing the thermal transfer efficiency between the fins and the cooling fluid. Multiple strips of mis-aligned cooling fins can be manufactured using a separate sheet for each strip, or by forming multiple strips in one sheet. In the latter case, the fin pattern can be created from a flat sheet using lancing by stretching or otherwise moving the sheet between lancing steps to produce the desired offset between adjacent strips. If the offset is 50% (i.e. half a period) and the fins extend over a length roughly equal to the length of the flat portions, then after the lancing adjacent strips are barely connected, and the sheet can be considered to have two sets of aligned strips interleaved with one another.

[0012] In some embodiments, the interconnecting portions are apertured. Single or multiple apertures may be provided in each interconnecting portion as desired. These apertures further assist cooling by facilitating turbulence in fluid flowing past the fins.

[0014] This method of assembly is particularly convenient and efficient. In this way, the folded sheet can be simply offered up and attached to the laser module in a single step.

[0016] A further significant advantage of using a folded sheet is that the folded sheet can be provided so that it is extensible and compressible by its interconnecting portions. The folded sheet can then be extended or compressed by a desired amount before bonding it to the cooling face in its extended or compressed state. This allows adjustment of the fin spacing, and the distance of maximum extent of the fins from the cooling face. This kind of freedom is not possible with a conventional fin array where the fin size and pitch is fixed at the time of manufacture of the fin array. It is possible to exploit this design freedom by varying the fin spacing according to the cooling requirements. Moreover, the fin spacing can be varied along a single sheet by different degrees of extension or compression along different portions, for example to provide different cooling capacity along the length of a cooling face to take account of hot spots. The folded sheet is thus extended or compressed by different amounts along different sections thereof so that the flat portions are separated by different amounts in the different sections.

Problems solved by technology

Second, the fins formed by the interconnecting portions of the sheet can present a high-drag to a fluid flow being forced past the fins by a fan or pump, thereby inducing significant turbulence which is an aid to carrying heat away from the fins.

Another suitable metal is copper which has a high thermal conductivity but is more expensive and more difficult to work with.

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