Inustry News—A Whirlwind Visit to Potential Glass Suppliers
   Gary Sanders

A project like TMT simply cannot take place without a strong industrial component. This space in the Newscast, "Industry News," has featured articles written by several of our current industrial partners (M3 of Tucson, Hytec of Los Alamos, AMEC of Vancouver). We also described a prospective primary mirror glass supplier, Corning, in our first "Focus On" article.

In this installment I want to describe the next steps in acquiring the hundreds and hundreds of finished primary segments that we will need for TMT (which Jerry Nelson began explaining last month, and finishes up in an article on polishing mirrors in this Newscast.)

Actually, this step was quite a bit of fun, though it involved grueling travel and long, but productive, work days. We have to buy glass. We must have the glass blanks polished to shape and tested by optical means. The finished segments must meet our demanding requirements and they must be as cheap as possible. The strategy is to contract with the most capable companies in the world through a competitive process. And so we have to come to know these companies and their capabilities, methods and products.

TMT-quality zero-expansion glass is currently supplied by Corning (Canton, NY), LZOS (Lytkarino, Russia), Ohara (Sagamihara, Japan), and Schott (Mainz, Germany). In our first "Focus On" article in June, we are photographed standing next to a TMT-shaped sample segment produced by Corning. But visits at a trade show do not provide the kind of detailed exploration of requirements and products that factory visits do. We must visit the four firms who may supply the glass blanks for TMT. This is a key early step in setting up a fair commercial competition. Unfortunately, these specialty glass suppliers are located in far-flung locales.

Similarly, our prospective segment fabrication firms are few and far and wide. We previously conducted a commercial bidding process that selected three firms or consortia to engage in the first stage of fabrication studies. The selected firms are ITT (Rochester, NY) teamed with Tinsley (Richmond, CA); SAGEM (Paris, France); and Zygo (Middlefield, CT). Each of these three partners has delivered a design for TMT segment fabrication and several studies have been initiated with glass prototypes. Visiting these firms is an essential step in refining the remaining commercial selection process.

We decided to start with a marathon visit to three of the eight firms listed above. So five senior members of TMT¹ gathered one recent weekend, on a warm sunny afternoon, to jet off to Moscow, where the temperature hovered near freezing and light snow flurries would remind us that we had departed California.

After a 12+ hour overnight flight and another long night of sleep, we visited the very impressive Soviet-era factory of LZOS, crown jewel of glass suppliers in Russia since 1939. Large boules of zero-expansion Astrosital entertained us, as did precision grinding, machining and polishing tools, and optical testing setups. Detailed discussions of thermal expansion, stress birefringence, homogeneity, and price filled a long day. The Southern African Large Telescope (SALT), a 10-meter segmented mirror, is fashioned from this Russian product. Clearly, LZOS has moved successfully from state ownership to the capitalism of a Joint Stock Company.

After a long day at LZOS, we spent our only evening in Moscow walking around the Kremlin and St. Basil’s cathedral. High above the ramparts of the venerable Kremlin, in the evening dusk, two bright luminous red stars marked the scene. Yes, these are the very glassy, illuminated red stars that have hung over the Kremlin through decades of the Cold War. And the red glass in those stars was made by LZOS, a reminder of the famed factory that we had visited hours before.

We traveled to Mainz, Germany the next day, where Schott paraded their Zerodur glass, used in the Keck 10-meter mirrors and in many other astronomy applications. Another long, but exciting, day spent in technical and commercial discussions was rounded out by a tour of the glass-processing facilities. There we saw a sample TMT segment blank produced by Schott and processed in a preliminary manner by SAGEM. The group gathered around this icon as it lay in an inspection machine.

Another dash by jet to Paris and another full day; this time at SAGEM (formerly REOSC), also well known in the astronomy business. The 8-meter Gemini and ESO VLT mirrors were made here, as were the recent segments for the primary mirror of the 10-meter Gran Telescopio Canarias (GTC) in the Canary Islands. Technical and commercial discussions and tours of circular and planetary polishing machines were capped by a first look at an experimental stressed mirror polishing setup for TMT segments (read Jerry Nelson’s companion piece on polishing). SAGEM has been working under contract to us for a year and its progress is visible in front of us.

After an evening in downtown Paris, a fine meal and a stroll about the iconic Eiffel Tower, the tired team smiles back at the camera in the photo. A vigorous week. Perhaps the smile is contemplation of the long ride home in the morning.

Ohara and Corning and ITT and Tinsley and Zygo will be next.

¹ Project Manager Gary Sanders, Business Manager David Goodman, Project Scientist Jerry Nelson, Telescope Department Head Larry Stepp, and Optics Group Leader Ben Platt made the trip.