How to Align a 12 Inch Beam Expander with DynaPhase

By Zygo | Published: 2026-10-18

Category: How-to Guides

Learn the step-by-step process to align a 12 inch beam expander for DynaPhase or wavelength shifting measurements, including common mistakes and setup tips.

Quick Answer

To align a 12 inch beam expander with DynaPhase, mount the expander on a stable 4' x 10' x 1' table, connect the mux cube, and follow the optical alignment sequence for wavelength shifting or DynaPhase measurement.

Understanding the Setup Requirements

The 12 inch beam expander for DynaPhase or wavelength shifting is designed for use with MST, MST+, HD-MST, HDX-MST, and Dynafiz systems. It does not support mechanical phase shifting, so alignment focuses on optical path consistency rather than mechanical adjustments.

A critical requirement is the table size: the expander and its mux cube need a 4' x 10' x 1' optical table. Without sufficient space, alignment becomes difficult and measurement stability suffers.

Common Mistakes to Avoid

One frequent error is attempting to use the wavelength shifting expander with a mechanical phase system like Verifire. The two expander types are not interchangeable—the mechanical phase version (Product ID 1713197) works with Verifire, Verifire HD/HDX, and Dynafiz, while the wavelength shifting version (Product ID 1713198) is for MST-based systems.

Another mistake is skipping the mux cube installation. The cube is included with the expander and is essential for directing the beam correctly. Omitting it leads to alignment failure.

Step-by-Step Alignment Process

Mount the Expander on the Table: Place the 12 inch beam expander on a 4' x 10' x 1' optical table. Secure it with mounting hardware to prevent movement during alignment. Check that the table is level and vibration-free before proceeding.
Install the Mux Cube: Attach the included mux cube to the expander's input port. Ensure it is seated properly and the beam path is unobstructed. A loose mux cube causes beam misalignment—tighten all screws finger-tight plus a quarter turn.
Connect to the Interferometer: Using the appropriate cables or optical guides, connect the mux cube to your MST, MST+, HD-MST, HDX-MST, or Dynafiz system. Verify the connection is secure. Use only the cables provided with the expander; third-party cables may not maintain alignment.
Power On and Initialize: Turn on the interferometer and the beam expander. Allow the system to warm up for at least 15 minutes to stabilize the laser and optics. Skipping warm-up leads to thermal drift—measurements will be unreliable.
Perform Coarse Alignment: Using the adjustment knobs on the expander, center the beam on the test surface. Look for a uniform circular spot with no clipping. If the beam appears oval or has dark edges, the expander is not centered—adjust the knobs in small increments.
Fine-Tune with DynaPhase Software: Open the DynaPhase or wavelength shifting software and use the alignment tool to optimize fringe contrast. Adjust the expander knobs until the software reports good signal strength. Do not rely solely on visual alignment—the software provides quantitative feedback that catches subtle misalignments.
Verify Measurement Stability: Take a test measurement and check for drift or noise. If the measurement is stable, alignment is complete. If not, repeat steps 5 and 6. If drift persists, check table stability and ensure no air currents are passing through the beam path.

Product Facts

12" Beam Expander- Wavelength Shifting/ DynaPhase: 12" Beam Expander for Wavelength Shifting or DynaPhase measurement (no mechanical phase); compatible with MST, MST+, HD-MST, HDX-MST and Dynafiz. If you are using a DynaPhase or wavelength shifting system, this is the correct expander—using the mechanical phase version will not work with your interferometer.
12" Beam Expander- Wavelength Shifting/ DynaPhase