Patent ID: 12191622

DETAILED DESCRIPTION

As will be described below, a layer of thermally conductive carbon such as, but not limited to, diamond or diamond-like carbon (DLC), is provided underneath or between high-reflector layers in HEL elements. The layer of thermally conductive carbon maintains a relatively good surface finish through sputtering or polishing operations, serves to spread heat until FOD is ablated or until shot completion instead of causing substrate damage and allows for active monitoring by a thermistor or another thermal sensor.

With reference toFIGS.1and2, an HEL element101is provided and includes a non-conductive substrate layer assembly110, a reflector layer assembly120and a thermally conductive carbon layer130. The non-conductive substrate layer assembly110includes a non-conductive substrate111with at least a major surface1110that is polished or super-polished and, in some cases, one or more thermal matching layers112(hereinafter, the one or more thermal matching layers112will be referred to as a single thermal matching layer112for purposes of clarity and brevity). The non-conductive substrate111can be formed of fused silica, for example. Where applicable, thermal matching layer112can be interposed between the major surface1110of the non-conductive substrate111and the thermally conductive carbon layer130to provide coefficient of thermal expansion (CTE) matching between the non-conductive substrate111and the thermally conductive carbon layer130. The reflector layer assembly120can include multiple broadband high-reflector layers1201,1202,1203, . . . ,120n(only multiple broadband high-reflector layers1201,1202,1203are shown).

The thermally conductive carbon layer130includes at least one of a diamond-like carbon crystal growth layer131and a diamond crystal growth layer132that is grown on or placed on or sprayed onto the major surface1110of the non-conductive substrate111of the non-conductive substrate layer assembly110in those cases in which no thermal matching layer112or general adhesion layer is provided. Conversely, where the non-conductive substrate layer assembly110includes the thermal matching layer112, the thermally conductive carbon layer130can be grown on or placed on or sprayed onto a major surface1120of the thermal matching layer112. In those cases where the thermally conductive carbon layer130is placed on the major surface1110of the non-conductive substrate111or the major surface1120of the thermal matching layer112, the thermally conductive carbon layer130can be provided as a pre-grown diamond substrate.

The following description will be directed to those cases in which the non-conductive substrate layer assembly110includes the thermal matching layer112. This is done for purposes of clarity and brevity and should not be interpreted as limiting of the overall scope of the disclosure in any way.

The thermally conductive carbon layer130is at least partially interposed between the major surface1120of the thermal matching layer112of the non-conductive substrate layer assembly110and a proximal one of the multiple broadband high-reflector layers1201,1202, . . . ,120nof the reflector layer assembly120(i.e., broadband high-reflector layer1201). In this way, the thermally conductive carbon layer130acts as a heat spreader for the non-conductive substrate layer assembly110and the HEL element101as a whole. In particular, where the reflector layer assembly120has FOD disposed thereon and the HEL is incident on the FOD disposed on the reflector layer assembly120and thus causes a temperature increase for the HEL element101, the thermally conductive carbon layer130spreads the heat.

In greater detail and as shown inFIG.2, the thermally conductive carbon layer130can include a planar layer portion133and sidewall portions134. The planar layer portion133is axially interposed between the major surface1120of the thermal matching layer112of the non-conductive substrate layer assembly110and the proximal one of the multiple broadband high-reflector layers1201,1202, . . . ,120nof the reflector layer assembly120(i.e., broadband high-reflector layer1201). The sidewall portions134extend around a portion of the non-conductive substrate layer assembly110.

A major surface1330of the planar layer portion133corresponds to the major surface1120and has a greater dimension (i.e., diameter) than the non-conductive substrate layer assembly110. The reflector layer assembly120can be formed with a cut-out or aperture122that exposes a section1331of the major surface1330of the planar layer portion133. Respective shapes of the cut-out or aperture122and the section1331correspond to one another and can be provided in multiple forms including, but not limited to, a chordal section as shown inFIG.2.

A thermal sensor140can be coupled to the thermally conductive carbon layer130. In accordance with embodiments, the thermal sensor140can be disposed at the cut-out or aperture122. In accordance with further embodiments, the thermal sensor140includes at least one of a first thermistor141that is coupled to a first surface of the thermally conductive carbon layer130(i.e., in the section1331of the major surface1330of the planar layer portion133) and a second thermistor142that is coupled to a second surface of the thermally conductive carbon layer130, which is perpendicular to the first surface of the thermally conductive carbon layer130(i.e., along the sidewall portions134).

With reference toFIG.3and in accordance with alternative embodiments, an HEL element301is provided. The HEL element301includes a non-conductive substrate layer310, a reflector layer assembly320with multiple broadband high-reflector layers3201,3202, . . . ,320n(only multiple broadband high-reflector layers3201,3202,3203are shown), a thermally conductive carbon layer330and a thermal sensor340. The HEL element301as a whole and the non-conductive substrate layer310, the reflector layer assembly320and the thermally conductive carbon layer330are generally similar to the HEL element101ofFIGS.1and2, except that the thermally conductive carbon layer330is at least partially interposed between first and second ones of the multiple broadband high-reflector layers (i.e., broadband high-reflector layers3201and3202).

With reference toFIG.4, a method of assembling a high-energy laser (HEL) element, such as the HEL element101ofFIGS.1and2and the HEL element301ofFIG.3, is provided. As shown inFIG.4, the method includes forming a non-conductive substrate layer assembly (401) by, for example, polishing a surface of a non-conductive substrate (4011) and, in some cases, applying a thermal matching layer to the surface of the non-conductive substrate (4012). The method also includes growing a thermally conductive carbon layer on the non-conductive substrate layer assembly (402) by, for example, over-spraying of at least one of diamond-like carbon and diamond (4021). In addition, the method includes masking a portion of a surface of the thermally conductive carbon layer facing away from the non-conductive substrate layer assembly (403), attaching a reflector layer assembly to an unmasked portion of the surface (404) and coupling a thermal sensor to the portion of the surface following an unmasking of the portion of the surface (405). The attaching of the reflector layer assembly to the unmasked portion of the surface of operation404can include assembling multiple broadband high-reflector layers into the reflector layer assembly (4041) and patterning the multiple broadband high-reflector layers to define an aperture in which the thermal sensor is disposable (4042). The coupling of the thermal sensor to the portion of the surface of operation405can include coupling a first thermistor to the portion of the surface (4051) and coupling a second thermistor to an additional surface perpendicular to the portion of the surface (4052).

In a FOD thermal analysis, a laser beam incident on a lens without a diamond substrate resulted in about a 1,600° C. rise in temperature of the lens (FOD diameter about 5 μm and thickness about 3.33 μm; lens diameter about 5 inches and thickness about 0.5 μm). By contrast, in another FOD thermal analysis, a laser beam incident on a lens with a diamond substrate resulted in only about a 25° C. rise in temperature of the lens (FOD diameter about 5 μm and thickness about 3.33 μm; diamond substrate diameter about 5 inches and thickness about 1 μm; lens diameter about 5 inches and thickness about 0.5 μm).

Technical effects and benefits of the present invention are the provision of an HEL element in which a thermally conductive carbon layer is at least partially interposed between a non-conductive substrate layer assembly and a reflector layer assembly to act as a heat spreader. The thermally conductive carbon layer thus protects at least the non-conductive substrate layer assembly from high temperatures resulting from a laser being incident on FOD on the reflector layer assembly.

The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

While the preferred embodiments to the invention have been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.