Large Lightweights
For customers with large lightweight mirror needs, HEXTEK offers borosilicate glass castings
up to 2.5 meters in diameter.
Large lightweight borosilicate mirrors have produced world class imaging and astronomical discoveries, proving
the their viability compared to Zerodur™ and ULE® mirrors. (See the
Magellan and MMT Telescopes)
Lightweight Casting Benefits vs. Zerodur™ and ULE® mirrors
- Rapid Thermal Response - Better "Mirror Seeing"
- Dramatically Stiffer than Thin Maniscus Mirrors
- Simplified Mounting Design
- Cost Competitive
The process for making casting blanks involves mulitple detail steps. The simplified process includes:
- optimizing the lightweight core configuration to support the optical requirements, - designing, fabricating and
assembling the hard refractory tooling in the furnace, - machining the soft core mold refractories and
fastening them to the hard tooling, - loading the mold with glass, - melting the glass, - fine annealing the blank,
- demolding the blank, - diamond machining it to tolerance in preparation for polishing. The pictures below show the
assembled mold in the furnace
, and the mold loaded with Ohara E-6 glass. Click this link to see the finished mirror for the
2.5 meter SDSS telescope.
