Our research group consists of members of the technical staff at both LLE and COM. Strong collaborative research is ongoing with Prof. Shaw Horng Chen, Prof. Matthew Yates, and Prof. Hong Yang in the Department of Chemical Engineering, and Prof. John Lambropoulos, Prof. Sheryl Gracewski, and Prof. Paul Funkenbusch, who are affiliated with the Department of Mechanical Engineering and the Materials Science Program.

Technical Staff

Mr. Kenneth Marshall is a research engineer in charge of the Liquid Crystal Materials Group at LLE where he also serves as the chemical safety officer. Mr. Marshall supervises students and staff in a variety of research projects. He is quite active in the LLE Summer High School Program.His student, Rui Wang, was an Intel Science Talent finalist in 2006 for her work on computational chemistry modelling.

• Electro-Optical Device Applications in Novel Liquid Crystal Systems
• Phase-Shifting Point-Diffraction Interferometer for Microgravity Fluid Physics (funded by NASA Glenn Research Center, Cleveland, OH). A process for preparing “structured” substrates (those in which the reference diffracting element are an integral part of the substrate, rather than a separately placed element) by means of photoresist processing was developed for the visible region, and ultimately the IR.
• Polymer LC Flake Technology and Applications in Electronic Imaging
• Lyotropic Polysaccharide Liquid Crystal Systems for Optical Applications
• New Materials: A series of new chiral IR dyes with improved solubility in liquid crystals were isolated and characterized. These new dyes show excellent prospects for applications in sensor protection and telecommunications in addition to inertial confinement fusion (ICF) application areas.

• Computational Chemistry: Methodologies are being developed for predicting the dielectric anisotropy and birefringence in low molar mass and polymer liquid crystals using semi-empirical computational chemistry. Work initiated in 2001 to calculate properties in polysiloxane and polymethacrylate LC oligomers with 1-3 repeat units was extended to molecular systems with 10-12 repeat units and initial results were obtained.

Recent Patents and Publications:

K. L. Marshall, "Liquid Crystal Devices Especially for Use in Liquid Crystal Point Diffraction Interferometer System," U.S. Patent #7,492,439 B1 (February 17, 2009)

K. L. Marshall, J. Gan, G. Mitchell, S. Papernov, A. L. Rigatti, A. Schmid and S. D. Jacobs, "Laser-Damage-Resistant Photoalignment Layers for High-Peak-Power Liquid Crystal Device Applications," in Liquid Crystals XII, edited by I. C. Khoo (SPIE, Bellingham, WA, 2008), Vol. 7050, paper 70500L

C. Kim, K. L. Marshall, Jl U. Wallace, J. J. Ou, and S. H. Chen, "Novel Cholesteric Glassy Liquid Crystals Comprizing Benzene Functionalized with Hybrid Chiral-Nematic Mesogens," Chem Mater. 20, 5859-5868 (2008).

B. Ashe, K. L. Marshall, D. Mastrosimone and C. McAtee, "Minimizing Contamination to Multilayer Dielectric Diffraction Gratings within a Large Vacuum System," in Optical System Contamination: Effects, Measurements and Control 2008, edited by S. A. Straka (SPIE, Bellingham, WA, 2008), Vol. 7069, paper 706902.

The Exocuticles of Beetles Contain Layers of Chitin, a Naturally Occurring Polysaccaride that Possesses a Cholesteric Liquid Crystal Structure Jewel Scarab Beetle -National Geographic

Dr. Ansgar Schmid is a Senior Scientist in charge of the Laser Damage Program at LLE. He supervises the operation of three laser damage testing facilities (see below). He conducts basic research to understand the mechanisms underlying initiation of damage in materials and thin films. For his research, Dr. Schmid uses several nano-metrology tools located in the COM/LLE Metrology Laboratory that include:

• A Digital Instruments Nanoscope III Atomic Force Microscope-version 2.2 (AFM) for taking surface topography maps with atomic scale lateral resolution; equipped to perform contact AFM, tapping mode AFM, non-contact AFM, lateral force microscopy (LFM), phase imaging, and nanoindentation at very low loads (Hystron Triboscope).
• A Witec Alpha Scanning Near-field Optical Microscope (SNOM) for studying surfaces with high resolution using scanning near-field optical microscopy, confocal microscopy, and atomic force microscopy in a single instrument.

Dr. Semyon Papernov is a scientist at LLE. He is responsible for operating the conventional laser damage testing facility at LLE. He is also the principal operator of the Digital Instruments Nanoscope III Atomic Force Microscope in the COM Metrology Laboratory. For the past several years, Dr. Papernov has organized and taught a course in AFM theory and techniques to graduate students in Materials Science and Mechanical Engineering.

Mr. Kozlov, Dr. Papernov and Dr. Schmid collaborate on fundamental studies of laser damage. Some of this work includes the introduction of extrinsic artifacts (e.g., engineered defects) into thin films .

Laser Damage Testing Facilities:

Conventional Testing Facility, Location: LLE Rm. 135
Status: Operational with high reliability
Description: Frequency-converted, flashlamp-pumped Nd: glass w/ zig-zag slab
l/Pulsewidth: 1w red/1 ns; 2w green/0.8 ns; 3w blue/0.6 ns
Pulse shape: gaussian Rep rate: 8 shots per minute Beam size: 0.6 mm
Methodology: 1-on-1 or N-on-1; damage assessed by dark field microscopy @110x
Applications: 3w/0.6 ns– new HR/AR materials, processes, designs
1w/1.0 ns– high power diffraction grating concepts

Short Pulse Testing Facility, Location: LLE Rm. 132 Status: Operational Description: Positive Light Inc., Ti:sapphire + glass, chirped–pulse @ 50 mJ l/Pulsewidth: 1w red only/0.5 ps to 10 ps; 100 ps possible w/ different compressor Pulse shape: “gaussian” output from compressor
Rep rate: 1 shot per minute (glass rod limited) Beam size: 1 mm Methodology: 1-on-1 or N-on-1; damage assessed by dark field microscopy @110x Applications: HR/AR film designs, beam combiners, off-axis parabolas Diffraction gratings by photopolymerization, (reactive ion-) etching, ion-milling

Shaped Pulse Testing Facility, Location: LLE Rm. 134
Status: Operational
Description: Nd: glass pumped Large Aperture Ring Amplifier for 30 J
l/Pulsewidth: 1w red/1 ns to 3 ns; 3w blue/1 ns to 3 ns (possibly 4-5 ns)
Pulse shape: “square” and “Haan” Rep rate: 1 shot every 20 minutes
Beam size: 16 mm diameter (2-cm²)
Methodology: 1-on-1 or N-on-1 (with N a small number)
inspection/assessment TBD depending on spot size
Applications: 1w/3 ns or longer square pulse - scaling for red transport: HR’s/AR’s
3w/3 ns or longer square pulse - scaling for blue transport: HR’s/AR’s

Recent Publications:

S. Papernov and A. W. Schmid, "Testing Asymmetry in Plasma-Ball Growth Seeded by a Nanosecond Absorbing Defect Embedded in a SiO2 Thin-Film matrix Subjected to UV Pulsed-Laser Radiation," J. Appl. Phys. 104, 063101 (2008).

S. Papernov and A. W. Schmid, "laser-Induced Surface Damage of Optical Materials: Absorption Source, Initiation, Growth and Mitigation," in Laser-Induced Damage in Optical Materials: 2008, edited by G. J. Exarhos, D. Ristau, M. J. Soileau and C. J. Stolz (SPIE, Bellingham, WA, 2008), Vol. 7132, p. 71321J (Keynote Paper).

J. B. Oliver, S. Papernov, A. W. Schmid and J. C. Lambropoulos, "Optimization of Laser-Damage Resistance of Evaporated Hafnia at 351 nm," in Laser-Induced Damage in Optical Materials: 2008, edited by G. J. Exarhos, D. Ristau, M. J. Soileau and C. J. Stolz (SPIE, Bellingham, WA, 2008), Vol. 7132, p. 71320J.

Damage crater produced by 351nm pulse in SiO2 thin film doped with 8nm gold particles.

Ms. Amy Rigatti is head of Optics Manufacturing (OMAN) at LLE. She manages the activities of a group of ~25 engineers and technicians who are responsible for the design, acquisition or manufacture, testing, installation, and maintenance of almost all the optics used in OMEGA, the 60 beam Nd: glass laser system at LLE, as well as OMEGA EP, a 4 beam Nd: glass laser system used in ultra-high-intensity laser-matter interaction studies. Amy is also responsible for managing contract work with outside organizations like LLNL in California and CEA in France.

Thin-film coatings are deposited on a range of substrate materials to meet antireflection, reflection, or beam-control requirements at specific angles, wavelengths, and polarizations. Optical coatings must achieve the necessary resistance to laser-induced damage, produce the desired change in spectral and photometric performance, and maintain the surface figure of the finished substrate.

OMAN’s coatings consist of two primary types:

• reactive physical vapor deposition (PVD) of oxides via electron-beam evaporation for all hard coating types, especially those that have complex spectral requirements at multiple angles, wavelengths and polarizations.
• liquid deposition of suspended silica molecules (sol-gel) via spin- or dip-coating techniques for high-performance antireflection coatings, especially in the highest fluence applications.

OMAN maintains clean room facilities for substrate preparation and inspection prior to coating, and for the manufacture of liquid-crystal polarizers and wave plates. The group takes on large-scale research and development challenges for outside customers. Currently, OMAN is responsible for the manufacture and delivery of 1w HR mirrors and polarizers for the National Ignition Facility at LLNL. It is also performing deformable mirror fabrication for NIF.

OMAN has its own laser damage test facility with the following attributes:

Long Pulse Testing Facility (Sparky), Location: Annex Rm. 180
Status: Operational in the red 1w, but not yet in the blue 3w
Description: Spectra-Physics (LLNL) high-rep-rate, flashlamp-pumped YAG
l/Pulsewidth: 1w red/10 ns; 3w blue/6 ns Pulse shape: gaussian
Rep rate: 10 shots per second (operated @ 20 shots per minute) Beam size: 1 mm
Methodology: –1w raster scanning over 50 mm part; damage assessed by dark field microscopy @110x if a spark is detected; lower rep-rate 1-on-1 and N-on-1 modes possible
–3w N-on-1 testing when available
Applications: 1w/10 ns–required for HR and polarizer production QA in support of the National Ignition Facility (NIF) Program at LLNL
3w/6 ns– new HR/AR materials, processes, designs

OMAN's 54 inch vacuum chamber (background) with an ion-etch capability to produce distributed phase plates.

Mr. Alexander Maltsev is the supervisor of the LLE Optical Fabrication Shop. As a master optician, he is responsible for carrying out unique manufacturing projects in support of LLE and other University research programs. Mr. Maltsev turns out precision, one-of-a-kind optical elements from specialty glasses and crystals.

Products include prisms, etalons, and other specially shaped optics. He also maintains and operates a large continuous polishing machine used to polish 300 mm diameter flats to lambda/20 precision.

Every other spring, Mr. Maltsev teaches the laboratory sessions for Optics 443: Optical Fabrication and Testing, a graduate elective offered through The Institute of Optics. In this course, students learn how to hand-fabricate and test precision optics, starting from a glass block.