Gratings are written with Scanning-Beam
Interference Lithography (SBIL) using the nanoruler.
Utilizing an array of custom processing
equipment and techniques, PGL can process a wide range of optical substrates.Current
maximum size is about 93 cm x 60 cm. Plans are underway to make a machine
with 1.3 to 1.5 meter capability
SBIL produces a highly accurate linewidth that results in excellent diffraction
efficiency that is both uniform and repeatable from part-to-part. By precise
control of the grating exposure and phase, PGL’s SBIL technology is the
only known technique that allows for correction of wavefront errors in substrates
and apodization of incident beams. The scanning technique of SBIL overwrites
with a gaussian distributed energy band of laser light that provides a high
level of dose control resulting in consistent aspect ratio, high efficiency,
and period repeatability of over 10ppb part-to-part.
and MIT are working toward writing more complex gratings with Variable-Period
Scanning-Beam Interference Lithography (VP-SBIL). VP-SBIL capacity
allows for a quick changeover for periods from 200 nm to 25 µm. VP-SBIL
has been tested at 100, 200, 500, 1000, 1740, 2500 and 5000 lns/mm.
Due to the high degree of automation in the tool,
period can be changed and ready to write on large samples in < 1 hour.
PGL now writes gratings with two or more periods on the surface. Coarse
gratings are used for measurement of grating thickness.
Ion Beam Etching
PGL uses a large area reactive ion etcher to etch
photoresist gratings into various silicate glasses.
Here a grating is mounted in the etch
chamber. The ion source is in the foreground.
The PGL Ion Etcher uses a scanning method to achieve high etch uniformity.
Etched MLD diffraction efficiency
is uniform and high across the part.
PGL can accurately map diffraction efficiency
across large parts to determine etch uniformity.
Sandia Compressors (600mm x 210 mm)
C3 DE Average 0.97
C5 DE Average 0.98
C1 DE Average 0.965
Liquid Film Coating
meniscus coater applies photoresist to the substrate. The meniscus coater
pulls the substrate over a meniscus of fluid. Small substrates are held
upside down by a vacuum while large substrates are held by a groove in
A 1.1 meter chamber is used for development of
complex multilayers and energetic processes such as ion-assisted deposition.
› Two electron beam sources
› 12 cm RF Ion Source
› Optical Monitor
› 19” Dia. Planetary Rotation
› Used for development of PGL coating control software “Designlink”
Large Optic Handling
Coating Tooling is designed to allow thermal expansion of the substrate
and tooling without damage to the optic. Handling tooling allow for safe
handling of the substrate.
Special packaging protects substrates from contamination.
here to see our Measurement page
Area Pulse Compression Gratings Fabricated Onto Fused Silica
of Large Diffraction Gratings SVC 2007