Advanced Photon Source

An Office of Science National User Facility

Crystal Optics

Elina Kasman cutting grooves into optical pitch on 36" continuous polisher.Crystal-based X-ray optics are essential and critical optical components of synchrotron light sournces and XFELs. The Crystal Optics section has comprehensive in-house infrastructure, capabilities and expertise for fabricating and developing almost all kinds of crystal-based X-ray optics, including crystal monochromators, analyzers, high-heat-load monchromators, beam splitters, polarizers, mirror substrates, ultrahigh-resolution crystal optics systems, FEL crystal optics, etc., for APS beamlines as well as other DOE light sources, and neutron facilities.

Expertise includes:

  1. Designing crystal optics with X-ray dynamical-theory calculations and modeling to achieve desired resolution, efficiency, acceptance, etc.,
  2. Fabricating (and refurbishing) ultrahigh-quality crystal optics (Si, Ge, quartz, sapphire, diamond), from precise orienting, cutting/dicing, grinding, etching, to strain-free polishing
  3. X-ray characterization and testing of crystal optics using X-ray topography and double-crystal rocking curve imaging.

Work requests can be submitted by filling the Optics Group's work request from.

The crystal optics facilities are described below.

Dicing/Cutting Laboratory (COF2)

The lab is equipped with (1) two dicing saws for precisely and delicately cutting relatively thin wafers and plates into distinct pieces, (2) a rotary diamond blade saw for cutting large crystal boules, and (3) diamond-wire saw for cutting/slicing crystal boules of Si and Ge up to 8 inches in diameter and length. The diamond-wire saw cuts crystals very gently with low strains/damages and minimal loss of valuable material.

Etching Laboratory (Bldg. 401/L0104)

This facility is used to etch crystals using wet chemical methods (mainly HF and HNO3) to remove surface layers that have stresses/strains/damages induced by machining processes.

Polishing Lab (COF3)

The Polishing Laboratory utilizes the following lappers/polishers (in addition to various small polishers and lappers):

Hyprez LM28 Lapping Machine (Engis)

This machine is used for planarization and thinning of optical components up to 300mm diameter on hard pad or composite copper lapping plate.

Strasbaugh 6CM Continuous Polisher

This 36" table machine is set up with optical pitch for fine low-angstrom polishing of single crystal optical components and substrates using colloidal silica slurry. For best results, parts up to 200mm diagonal can be polished, in some cases parts up to 300mm diagonal can be accommodated.

Strasbaugh 6DF-1 Precision Polishmaster

This versatile overarm polisher can be outfitted with variety of plates and pads to perform intermediate and fine polishing steps, using diamond or colloidal silica slurries.

A novel home-made automated machine for polishing channel-cut crystals

This new home-made instrument can be used for machine polishing of channel-cut crystal
surface or other special-shaped crystal surfaces that do not have top flat surfaces (so that they
cannot be polished by normal polishers). It can achieve strain-free channel-cut walls with
roughness also toward 1Å.

Inspection Equipment

Example of sapphire crystal (078) orientation: Superimposed Laue pattern and simulation results in red by LauePt - a software tool developed by X. Huang.The Fabrication Laboratory is equipped with DIC microscope for immediate inspection during polishing process. Optics requiring more detailed inspection and accurate measurements are sent to the Metorology Laboratory.

Other Equipment (in collaboration with the ANL Central Shops)

Two high-precision grinders; Blanchard precise grinder; several overarm polishers; core drill press; and Ultrasound mill.

X-ray Laboratory (Bldg. 401/L0111 and 401/L0120)

Laboratory topography stations This laboratory is equipped with three main instruments:

  1. Two-axis Rigaku diffractometer (with Cu or Mo x-ray tube) for precisely orienting single crystals along required lattice planes with precision ≤0.1°.
  2. Back-reflection Laue camera (with Cu or Mo x-ray tube) for identification/verification of crystal orientations, equipped with the LauePt simulation software (developed in-house by Xianrong Huang) for studying the orientations of any single crystals with high precision up to 0.1°.
  3. Topo Unit, consisting of 18kW rotating-anode X-ray generator and a double-crystal diffractometer, can measure high-resolution (strain sensitivity better than 10-6) double-crystal rocking curves of silicon, germanium, diamond, etc. and take topography images (with a CCD detector) on each point of the rocking curve. The X-ray beam size can be up to four inches in diameter, allowing to reveal macroscopic strains of large crystals (including X-ray monochromators mounted on fixtures). A ultrahigh-precision stage is under development for orienting crystals with precision toward 0.01o.

Advanced X-ray characterization of crystal optics is carried out at the 1-BM Optics and Detectors Test Beamline.

Crystal Optics Research and Development

Design of high-resolution (10 meV) crystal analyzer system using a Montel mirror and angular-dispersion optics for RIXS.R&D in crystal optics is carried out either independently, or jointly with the APS beamline scientists and user community, or in collaboration with other facilities to keep the group at the state-of-the art in x-ray optics. Examples include designing and development of high-to ultrahigh- resolution crystal monochromators and analyzers (from sub-10 meV to sub-meV) for IXS/RIXS, strain-free crystal polishing with roughness toward 1A, automated machine polishing of channel-cut crystals, quartz-based X-ray optics, diamond optics, SiC optics, etc.