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Spectrophotometer - LAO

Large Area Optics (LAO) lab Operational

Our Large Area Optics (LAO) laboratory is now complete and fully operational.  The large spectrophotometer was installed in August and joins the coating machine and the substrate cleaning system in a purpose-built ISO 6/7 clean room. The spectrophotometer can take spectral (wavelength) data at any point on a 750 mm diameter substrate and at any spatial interval while under full automatic computer control.  It was custom designed and built to Materion performance specifications, as were the other pieces of equipment comprising the Laboratory.

The Large Optics project has been enjoying impressive results.  We achieved immediate success in coating large narrow bandpass filters for the Hyper Suprime Camera (HSC) for the Subaru telescope on Mauna Kea.  Here is a run-down of some of our accomplishments since the lab came on line.

Photo: Materion large spectrophotometer with Subaru HSC filter.

Recent Large Area Optics Lab Projects

Subaru Filters for HSC
The Deposition System was powered up in early 2013. We began coating the first of four 600 mm diameter Subaru filters in January and completed them in mid-August. We immediately achieved impressive results with great consistency - allowing us to fine tune our process.  We created two compliant NB 515 filters before moving on to the remaining filters.  Each subsequent band was successfully coated on the first attempt.  High yield is extremely important since the substrates are provided by the customer and are extremely expensive. 

We produced an NB 921, an “X-Band” at 948 nm and finally, the most difficult of the set, an NB 101.  All were comfortably within the specification.  HSC is a 900 megapixel camera with the widest field of view of any current large telescope which holds the survey instrument world benchmark for performance.  HSC replaces the smaller Suprime Camera for which Materion previously supplied filters.  HSC was installed on the telescope in August 2012 and after a three month engineering phase went on line for scientific observations.  Presently, Subaru is using a set of wide bandpass (WB) filters and will switch to our narrow bandpass (NB) filters in 2014.  The filter changer can hold only six filters so the filter swap from WB to NB which takes the telescope off-line,  is a major task involving a great deal of planning and coordination to avoid extended down time for the telescope.

Antireflective Coatings on Large, Curved Optics
Following the Subaru filters, we coated two very large lenses for the Kiepenheuer Institut fur Sonnenphysik (KIS).  This was the first demonstration of our capability to deposit AR coatings on large, curved optics.  The optics will be used in an instrument called Visible Tunable Filter (VTF) being developed in Germany for a future US telescope called Advanced Technology Solar Telescope, which will be the largest solar telescope in the world when operational.  The telescope is being built on Haleakalā Hawaii. 
Large H-alpha Red Glass Substrate

Large Red Glass Substrate
Our third challenge was to coat a narrow H-alpha BP [H-alpha refers to the hydrogen emission at 656nm and is a common wavelength used by astronomers] similar to the Subaru filters, but on a large red glass substrate.  This would not necessarily be our first choice of substrates, but the customer had purchased the glass in the Ukraine earlier. Since this glass required an expensive, special dedicated “melt,” they wanted to make use of it.  The filter will be installed in the 268 megapixel SkyMapper telescope at Siding Spring Observatory, Australia.  Currently, they are using wide bandpass filters (like Subaru) but wanted to take advantage of our new ability to coat large narrow filters.  The team using the H-alpha filter is lead by Nobel Laureate Brian Schmidt, a 2011 Nobel Prize winner in Physics, who provided evidence that the universe is expanding. 

                                                                                                                 Photo: Large H-alpha red glass substrate before coating.
New BP Filter Project in Korea
Materion is beginning a new job that entails the coating and testing of a set of five large BP filters –  4 WB and one NB  - an H-alpha similar to the Australian filter, but on a fused silica substrate.  This set is the first of three planned to be installed in the Korean Microlensing Telescope NETwork (KMTNet).  The telescopes are being built in Tucson but will be installed first in Las Campanas, Chile, then South Africa and Siding Spring in order to survey the entire Southern sky with 24 hour coverage.  This is our first major SS&A job for Korea and is a high profile project in the astronomy community that will extend until the end of 2013.

Upcoming Astronomy Projects

Other projects are expected in Q1 2014.  They involve telescope upgrades for current astronomy customers and could consist of sets of four to six filters each, depending upon funding.  Another pending job is for an Australian university where the optic will be used in an instrument being developed for the American Giant Magellan Telescope (GMT).  We are also anticipating a development phase project expected to be announced in late 2013 or Q1 2014. It is a precursor to a six filter “science” filter set which will be the largest bandpass filters ever produced at 750 mm diameter and on curved substrates.

So to date, we have successfully worked on projects from astronomers in five countries for use in telescopes located in Chile, Australia, and Hawaii.  We continue to receive inquiries regarding our new capability from observatories worldwide and for projects planned over the next several years.

The future appears bright for our Large Area Optics Lab. We offer a capability matched by few other facilities in the world. We have demonstrated our ability to coat narrow and wide bandpass filters and AR coatings that achieve superior performance.  Over the next several months, we will be developing other filters, including dichroic beamsplitters, enhanced mirrors and notch filters. Stay tuned!

For more information about our Large Area Optics Lab and Materion coating capabilities, contact Tom Mooney, Product Engineering Manager, Space & Astronomy, at: Thomas.Mooney@Materion.com