FNL Gradient Index Flexible Film Lens Inflatable to Rigid Frame Heliostat

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Gradient Index Flexible Film Lens Inflatable to Rigid Frame Heliostat
Est. Weight of Lens System: 21.36 kilograms
Est. Volume of Lens System: 0.012 m^3
Area of Lens (or less desirable Metalized Film): 12.6 m^2
Please Click On Show More for Additional Details and Fabrication Notes

The exterior construction is of a layered composition over wrapping an interior pressure bladder or inner tube. The layering is such as the exterior layer is for restricting the expansion of the inner tube as well as providing for encapsulating the assembly in an air tight manner, the intermediate layer is a prepreg carbon fiber composition, and the interior pressure tube. To deploy the interior tube is inflated from either an onboard tank of a gas generator or a high pressure gas. The tank should designed such upon deployment it can either double as a sample storage container or the container itself should also house low packing density sub-components of the rover with appropriate bulkheads. Such that a portion of the rover could even be designed as a monocoque hull to provide for the pressure vessel and housing of components etc. The pressure of the inner tube against the exterior layer in addition to the high temperature during the lunar day and the intentional black body form of the expanding frame should provide sufficient heat but not sufficient for curing as the Tg to maintain structural stability needs to be higher than the lunar day temperature, such that with an added flexible heat tape running in the tube or on the exterior additional heat is provided merely for the initial cure, provides for the curing of the prepreg carbon form such that pressure need not be maintained longer than the duration of curing for structural stability. In that the prepreg epoxy is chosen such that its curing temperature is chosen to maintain a Tg higher than that of the lunar day temperature high structural integrity will be maintained during normal lunar day temperatures. It should be noted that additional layered tubes could be provided for further structural support as required or to provide for structural framework etc.

The web of this version is comprised of a gradient index flexible thin film. The film could be provided with thin exterior films to minimize damage and extend life against UV exposure. The gradient index film could be fabricated using either partial polymerization or direct laser writing methods of manufacturing. If partial polymerization is utilized it is suggested that a UV laser source is used in a cnc system to provide a highly tuned fabrication process for the variation of the refractive index.

To keep the film as thin as possible it is likely best to have one solid surface area with a plurality of gradient index lenses formed in the thin film as the total film area increases. Or if optic considerations allow a single lens may suffice depending on focal lengths and desired surface area etc. That is, it should be noted, that there are slight tradeoffs in the simplicity/complexity of the lens fabrication, thickness, focal length, and total desired area. As the area increases over the proposed 12 m^2 the complexity of fabrication increases etc. Although the focal length is generally understood to be considerable a plurality of lens portions within the singular film should not be required and a single film could be used to simplify mfg.

Another method of fabrication for the gradient index film, as to the best of my knowledge, untested by conventional standards is the use of 3D printing whereby the stock material itself could be augmented as deposited onto a thin film as the substrate. This could further produce a novel structure for a gradient index thin film fresnel lens to further lightweight the film and total system weight. Here it should be noted that whereas such a method would likely be insufficient for optical systems it should far outperform mirror surface types of power transmission due to the inherent fact that it is not only the flatness of the surface it is also the combined directional accuracy of multi part arrays that must be addressed as any deviation between the plates would compromise the output. Herein the proposed concept a monolithic lens would far out perform other systems.

Further should the thickness of the gradient index lens need increased flexibility could be maintained through the use of stacked thin sheets for the web with the appropriate gradient index applied to each sheet. This would allow and maintain for flexible and pliable storage while greatly increasing the level of convergence versus a single monolithic lens in thickness which would be inflexible etc. Here as the intention is to focus for power transmittance approaching the level of optics is not necessarily required allowing for slight misalignment between layers while still outperforming the mirror alternative in performance and weight etc. Such a construction method would also negate such a need for a near perfectly flat surface although the proposed structure once cured should sufficiently meet the flat surface requirement nonetheless.

(While the gradient index should be sufficient for focusing the solar power other implementations could be employed such as having a layered film composite whereby an intermediate layer could be constructed in a traditional manner of a Fresnel lens utilizing a tilting axis cnc laser system. Although this would be less preferred regarding manufacturing and performance.)

The lens could be operated such as to provide for parallel ray illumination or could be turned 180 to allow converging rays for specific targeting of solar arrays on opposing rover(s) for rapid recharging.

The prepreg thickness may need adjusted dependent on expected loading requirements due to rover motion and required rates of adjustment of the lens position.

Alternate Mirror Film Heliostat

The web of this version is fabricated from a thin metalized film. The structural prepreg members could be further augmented such as to provide a frame for a parabolic or other shaped mirror form for focusing.

Solar Panels

Solar panels are kept on the rover in a conventional manner as the clear gradient index Fresnel lens will not impact the loads severely. In addition adding the weight of the solar panel to the heliostat would increase the size and power requirements of actuators. For the mirror metalized film the solar panel could be added to the system merely by having the inflatable prepreg carbon structure account for mounting of the panel and increasing the overall size to account for the decreased surface area of the metalized film.

Operation

The subsystems of conventional design such as solar intensity sensors, antenna, and 2 axis tracking motors are not shown. Conventional systems are sufficient for panning however the one alteration for the tilt is to use two scissor screw type jack actuators at the base with rotating connecting points such as to minimize the size of the alternate components due to the torque load required for quick alterations to tilt. Simple “boots” or covers are provided at these locations to mitigate concerns regarding lunar dust. Another beneficial component to reduce weight is to have motors operating in pairs and located by components requiring heating for operation, instead of adding a separate heat source the motors in pairs could be actuated in opposition producing no motion of the system but to produce heat for those required components a simple temperature sensor could ensure that the loads on the motors do not exceed their capacity.

During Transit

During travel the lens system merely tilts to parallel with the top surface of the rover to lower the center of gravity etc. Other supports for the lens could be provided in a manner similar to motorized artillery vehicles where the barrel is supported such as to further provide support to the lens during travel.

Technical Details as Shown

Approximate Weight of Lens: 21.36 kilograms

This weight could vary depending on the required thickness of the gradient index film for the required focal lengths. As well for the metalized mirror web if additional structural prepreg tubes are required the weight would increase accordingly.

Approximate Volume of Lens: 0.012 m3

Packaging or cube is enhanced due to the overall flexibility of the system such that it could be fitted into crevices so long as testing indicates free form removal upon actuation of the gas generating chemical combination or from a high pressure gas. As shown the lens is merely folded in a flat rectangular form.