Abstract: A head-mounted display configured to be worn by a user includes a housing and a headband configured to secure the housing to a head of the user. The headband includes a proximal end coupled to the housing and a distal end that is free from connection to the housing. The head-mounted display includes an adjustment mechanism configured to change a fit of the headband relative to the head of the user.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for optimizing a process of manufacturing a product. In one aspect, the method comprises repeatedly performing the following: i) selecting a configuration of input settings for manufacturing a product, based on a causal model that measures causal relationships between input settings and a measure of a quality of the product; ii) determining the measure of the quality of the product manufactured using the configuration of input settings; and iii) adjusting, based on the measure of the quality of the product manufactured using the configuration of input settings, the causal model.

Abstract: A compressor assembly for use with a Pulse Tube cryocooler is disclosed. The compressor assembly includes a central hub having a plurality of faces, and at least four compressor modules mounted on the central hub. Each of the compressor modules is mounted on a face of the plurality of faces. Each compressor module comprises a piston mounted in the central hub and configured to reciprocate along an axis of travel within the central hub. The pistons are mounted head-to-head with each other and collective reciprocation of the pistons along the respective axes minimizes vibration forces of the compressor assembly in X, Y, and Z translational axes of motion.

Abstract: A heat exchanger for use with a refrigeration device having a FPA disposed therein being comprised of a polymeric composite mesh material having a hot end and a cold end and defining an array of weft capillaries interwoven with a perpendicular array of warp strands. The array of weft capillaries may include a plurality of high pressure inlet capillaries for channeling and distributing high pressure gas from an inlet at the hot end to a Joule-Thomson orifice at the cold end, a plurality of low pressure outlet capillaries for channeling and distributing high pressure gas from a Joule-Thomson orifice to an outlet of the heat exchanger, and a plurality of low thermal conductivity fibers interspersed between the high pressure inlet capillaries and the low pressure outlet capillaries. In example embodiments. the array of warp strands comprises at least one or more of carbon fibers, copper fibers or glass fibers.

Abstract: A pulse tube cryocooler (PTC) includes an etched glass substrate bonded to a glass plate and defining one or multiple stages or layers. The PTC includes a plurality of channels etched into a surface of the substrate to define a heat exchanger, a pulse tube, a cold heat exchanger or cold head, a regenerator and an aftercooler. The bonded substrate and plate encloses the plurality of channels to form capillaries operable for conducting and distributing fluid. The pulse tube is disposed between the cold head and the heat exchanger and the regenerator is disposed between the cold head and the aftercooler. The heat exchanger is connected to a valve or inertance tube which, in turn, is connectable to a buffer tank or reservoir that contains fluid. The aftercooler is connectable to an external compressor operable for oscillating movement, which increases and decreases pressure and temperature within the PTC.

Abstract: A system, apparatus and method for a compressor hub assembly configured for use with a dual piston compressor is provided and includes a cylindrically shaped body having a centrally located inner wall and defining cylinder sealing surface for receiving and maintaining at least one compressor pump; a plurality of bores integrated within the body, the bores defining at least one fill port, a fluid inlet port, an output port, at least two compression bores, an off-center cross-bore interconnected with the one of the at least two compression bores, and at least one reservoir passages; at least one check-valve assembly disposed in the output port, the check valve assembly including a check valve, a valve seal and a valve retainer, wherein the use of the check valve assembly and the plurality of bores produces a continuous DC flow output when fluid is flowed through the compressor pump and into the hub assembly.

Abstract: A heat exchanger for use with a refrigeration device having a FPA disposed therein being comprised of a polymeric composite mesh material having a hot end and a cold end and defining an array of weft capillaries interwoven with a perpendicular array of warp strands. The array of weft capillaries may include a plurality of high pressure inlet capillaries for channeling and distributing high pressure gas from an inlet at the hot end to a Joule-Thomson orifice at the cold end, a plurality of low pressure outlet capillaries for channeling and distributing high pressure gas from a Joule-Thomson orifice to an outlet of the heat exchanger, and a plurality of low thermal conductivity fibers interspersed between the high pressure inlet capillaries and the low pressure outlet capillaries. In example embodiments. the array of warp strands comprises at least one or more of carbon fibers, copper fibers or glass fibers.

Abstract: The performance of a multi-stage inertance pulse tube cryocooler in accordance with an embodiment of the present invention may be enhanced by cooling the inertance tube of one stage placing it in thermal communication with the cool heat exchanger of a preceding stage. Cooling at least one inertance tube of a multi-stage cooler in this invention lowers the viscosity and sound speed of the gas in the inertance tube, thereby improving the cooling power for that subsequent cooling stage, and for the entire device.

Abstract: The performance of a multi-stage inertance pulse tube cryocooler in accordance with an embodiment of the present invention may be enhanced by cooling the inertance tube of one stage placing it in thermal communication with the cool heat exchanger of a preceding stage. Cooling at least one inertance tube of a multi-stage cooler in this invention lowers the viscosity and sound speed of the gas in the inertance tube, thereby improving the cooling power for that subsequent cooling stage, and for the entire device.

Abstract: A pulse tube cryocooler (90) is disclosed having a second cryocooler section (94b) with a single pulse tube stage (35c), and having a first cryocooler section (94a) with a pair of pulse tube stages (35a, 35b). A first pressure oscillator (98a) is associated with the first cryocooler section (94a), while a second pressure oscillator (98b) is associated with the second cryocooler section (94b). The first cryocooler section (94a) and the second cryocooler section (94b) are fluidly isolated from each other. Therefore, the charge pressure, the pressure amplitude, oscillation frequency, and working gas in each of the first cryocooler section (94a) and the second cryocooler section (94b) may be independently selected/established.

Abstract: Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.