1. Field of the Invention
This invention relates to a lightweight aerogel reflector particularly one having a reflective layer on a low-density aerogel substrate and method for manufacturing same.
2. The Prior Art
Optical systems including space-based optical system often have need for large reflectors, including mirrors. Presently available under current ULE (ultra low expansion) glass technology, a mirror substrate with a density of 2.2 gms/cc is obtainable, which can result in mirrors weighing hundreds of pounds, which limits the size of the optical system according to launch payload constraints. If a lower density mirror substrate can be fabricated, larger reflectors and optical systems could be launched and deployed in space for improved observation of the skies and of the Earth below.
There has now been discovered a method for manufacture of lightweight reflectors having a substrate density considerably below the 2.2 gms/cc of the above prior art per ULE glass technology. In fact the present invention provides reflector substrates with densities approaching a full order of magnitude below presentday ULE glass mirrors to as low as 0.01 gms/cc or as expressed herein, 10 mg/cc.
The present invention employs a reflector substrate of low density or LD. By a low density or LD substrate as used herein, is meant one with a density of 10-500 mg/cc.
Such aerogel is typlified by high porosity and thus a rough surface not apparently suitable for optical substrate applications. In fact no prior art literature was found on low-density aerogel optical substrate applications. However, the present invention provides a method for adapting LD aerogels as suitable substrates for lightweight optical applications including mirrors.