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Laser glass development at SCHOTT


Laser glass development at SCHOTT Laser glass production research and development at SCHOTT SCHOTT has produced laser glass in ... – PowerPoint PPT presentation

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Title: Laser glass development at SCHOTT

Laser glass development at SCHOTT
Laser glass production research and development
  • SCHOTT has produced laser glass in

    Pennsylvania since about 1980
  • SCHOTTs Duryea site has complete responsibility
    for laser glass research and development,
    manufacturing, and customer support for the
    SCHOTT Group worldwide
  • Two developments of critical importance to the
    glass solid state laser community
  • Development of platinum particle free melting
  • Development of continuous melting of phosphate
    laser glass
  • Recent developments include
  • High repetition-rate laser glass APG-1/APG-2
    (gt10 Hz).
  • New broad-band phosphate and silicate laser
    glasses and higher-power repetition-rated
    phosphate glasses currently under development

Laser glass historical perspective - keeping pace
with the needs of fusion research
  • SCHOTT production began with silicate glass for
    Shiva in 1977
  • Production since 1983 has been dominated glasses
    based by on phosphorous
  • The spatial scale of our products has also
    increased over time

Development of continuous melting of phosphate
laser glass
  • The latest generation of high energy laser
    systems for ICF research (NIF, LMJ) demanded an
    unprecedented volume of laser glass to be
    produced over a limited manufacturing period
    while still meeting ambitious targets of internal
    quality and overall cost

Artist Rendition of National Ignition Facility
(NIF) Laser
Traditional laser glass was produced in a two
step process that includes remelting in a
platinum crucible
  • Starting materials would react with and alloy the
    platinum pot
  • However, refractory materials such as SiO2 are
    also dissolved into the batch, leading to
    inhomogeneity in the glass
  • Remelting of cullet glass in platinum avoids
    the alloying problem and makes high homogeneity
    glass possible
  • Remelting cullet glass still allows the inclusion
    of Pt particles

Elimination of platinum inclusions increases
laser damage threshold by 10X
  • In the absence of Pt inclusions, the damage
    threshold of laser glass optical components is
    now limited by the quality of the surface polish

Damage grows with successive shots above the
damage threshold
  • Redeposited platinum vapor of spatial size gt0.3?m
    can damage on the next shot
  • Below 0.3?m, the heat is conducted into the glass
  • Laser glass parts became unusable after only a
    few high power shots

The key to solving the Pt particle problem was to
dissolve the particles into the glass structure
as ionic Pt4
  • Platinum particles appear to be created at the
    start of the melt cycle
  • Dissolution is limited by diffusion of platinum
    away from the particle surface
  • Care must be taken to avoid the late arrival of
    Pt particles into the melt from condensed vapors

To meet schedule and cost targets NIF and LMJ
required both a new glass and a new manufacturing
  • The NIF laser alone required 3000 slabs (150
    metric ton) over 3 years with the following
  • Index uniformity to lt0.000001
  • Free of inclusions and bubbles larger than 100um
  • Residual hydroxyl content lt100ppmw
  • Platinum particle free
  • Free of all detectable striae
  • Low 1054nm absorption of lt.19 per cm

Beamlet eighteen liter rare earth doped phosphate
glass amplifier slab
Meeting the laser glass requirements in terms of
cost, quality, and rate of delivery for NIF
demanded the development of an advanced
manufacturing technology
  • Continuous melting runs 24 hours a day / 7 days
    per week
  • 100 Inspection, interferometry and laser damage

SCHOTT conceived, designed, and demonstrated the
full scale continuous production line from 1994
to 1999
  • Over 1400 laser slabs were first produced by the
    new continuous melting process in 2001
  • All technical specifications and targets for the
    NIF were surpassed
  • 26 of slabs were essentially perfect, far
    exceeding overall specifications for residual
    water, platinum particles and homogeneity
  • Laser glass deliveries for the NIF and LMJ were
    completed in March 2004

Current laser glass research and development at
  • Ongoing 2.8M Production contract for
    discontinuous melting laser slabs and rods.
  • Awarded 2.5M for development of next-generation
    silicate and phosphate laser glasses are under

Glass Type NdSilicate vs. LG-680 NdSilicate vs. LG-680 NdPhosphate vs. APG-1 NdPhosphate vs. APG-1 YbPhosphate vs. YbAPG-1 YbPhosphate vs. YbAPG-1
Key Progress FOMTM Bandwidth FOMTM Bandwidth FOMTM Bandwidth
Feb., 10 -2 6 nm -55 4 nm -5 5 nm
Sept., 10 1 / 164 11 / 6 nm 30 7nm 30 12 nm
Process Development Summary
  • SCHOTT has been a major supplier of laser glass
    since 1980
  • SCHOTT has also been active in the development of
    new manufacturing technology extending the
    operation range and lowering the cost of our
  • This activity has created at SCHOTT further
    understanding on glass and
    supported the application of our other products
    into the marketplace
  • The two most critical developments in the last 20
    years have been the availability of platinum
    particle free laser glasses and the continuous
    melting of phosphate laser glass
  • Our efforts in laser glass are industry
    recognized and promote our reputation as the lead
    supplier of optical materials for laser