ZYGO ZMI-4104C | VME64x Replacement Measurement Board

Description

Key Technical Specifications

ZYGO’s current measurement-electronics documentation groups the 4104(C) with its 2400 and 4000-series boards and states that these boards can be installed modularly in a VME chassis, with system expansion to as many as 64 measurement axes.

The 0.07 µW minimum optical-power figure is especially worth noting when evaluating an older system. It is not merely an electrical board specification—the quality and available optical signal from the laser/interferometer chain directly affect whether the measurement system can achieve its specified performance. ZYGO lists the 7702, 7714, and 7724 laser families as compatible with the 4104(C) configuration.

Application Scenarios & Pain Points

Precision stages create a different maintenance problem from ordinary industrial automation. A board can pass a basic power-on check and still produce unacceptable nanometer-level measurement error. For that reason, replacement testing has to include the optical measurement chain—not just the VME card itself.

Typical Applications

• Semiconductor Position Metrology: The ZMI system can provide closed-loop displacement feedback for precision wafer-stage and semiconductor equipment. ZYGO documents the 4104C in a nano-positioning application where it was used with a precision positioner and motion controller.
• Precision Motion Control: Four measurement axes on one VME64x board make the 4104C suitable for multi-axis stage measurement where synchronized displacement data is required.
• Nanometer-Scale Calibration: The interferometer electronics can serve as a measurement reference when validating the performance of precision actuators, stages, and positioning mechanisms.
• Research and Advanced Metrology: VME-based systems can combine several ZMI boards for multi-axis displacement measurement. The manufacturer states that the ZMI architecture can scale to 64 measurement axes.

Field Case:
ZYGO describes an application using a 7702 laser head, differential interferometer, and 4104C measurement board with a precision positioner. The setup demonstrated closed-loop stage control in 0.5 nm increments, illustrating why the 4104C should be evaluated as part of the complete laser/interferometer system rather than as an isolated VME board.

ZMI-4104C

Related Products

• ZYGO ZMI-4004 — Four-axis ZMI measurement board in the 4000 family. It is a close architectural relative, but the 4104C provides the 4100-series performance specification and should not be substituted without checking system revision and software compatibility.
• ZYGO ZMI-2400 — Earlier ZMI measurement-board family supporting one or two measurement axes. Its published resolution is 0.31 nm, making it a lower-axis/lower-resolution alternative to the 4104C.
• ZYGO ZMI Go! — Compact ZMI measurement electronics supporting up to four measurement channels, with modern motion-control interfaces including EtherCAT and SSI. It is a substantially different integration approach from the VME64x-based 4104C.
• ZYGO ZMI 7702 — Compatible laser source for the 4104(C) measurement architecture. It supplies the optical reference used by the interferometer system rather than performing the displacement calculation itself.
• ZYGO ZMI 7714 — Another compatible ZMI laser platform for the 4104(C). Check the exact optical configuration before assuming interchangeability with a 7702 installation.
• ZYGO ZMI 7724 — Compatible ZMI laser module/source listed by ZYGO for the 4104(C) family. Its role is optical excitation/reference rather than electronic displacement processing.
• ZYGO ZMI 501A — Stand-alone measurement-electronics enclosure providing two measurement axes. Unlike the VME64x 4104C, it is packaged as an independent enclosure.
• ZYGO ZMI Interferometers — Optical measurement heads that work with the ZMI laser and measurement electronics. The 4104C cannot generate meaningful displacement data without the appropriate optical input chain.

The Engineer’s Guide: Field Pitfalls to Avoid

⚠️ Do Not Judge a 4104C by a VME Power-On Test

A VME board can initialize normally while the optical measurement path is unusable. Low optical power, damaged fibers, interferometer alignment, or laser instability may be responsible for poor measurements.

How to avoid it: Test the board with a known-good compatible laser/interferometer setup and verify actual displacement output.

⚠️ Verify the Laser and Optical Configuration

ZYGO specifies compatible laser families including 7702, 7714, and 7724. The optical configuration matters as much as the board identification.

How to avoid it: Record the installed laser model, interferometer type, optical path, and connector arrangement before approving a replacement.

⚠️ Check VME64x Compatibility and System Revision

The 4104C is a 6U VME64x board. A physically similar VME board is not automatically an electrical or software-compatible substitute.

How to avoid it: Confirm the host chassis, slot requirements, system controller, installed ZMI software/driver revision, and synchronization architecture before installation.

Frequently Asked Questions (FAQ)

What is ZYGO ZMI-4104C?

The ZMI-4104C is a four-axis displacement measurement electronics board used in ZYGO’s ZMI laser interferometer measurement systems. It processes optical interferometer signals to calculate precision displacement. ZYGO classifies the 4104(C) as a 6U VME64x board.

How accurate is the ZMI-4104C?

ZYGO’s published ZMI specifications list 0.15 nm position resolution and 0.2 nm accuracy at maximum velocity (σ) for the 4104(C) configuration, with a maximum velocity of ±2.55 m/s.

These figures should not be interpreted as guaranteed system-level accuracy under every installation condition. Laser stability, optical alignment, interferometer configuration, environmental conditions, and mechanical vibration all matter.

How many axes can one ZMI-4104C measure?

One board provides four measurement axes. ZYGO’s modular architecture supports synchronization of multiple units, with the overall ZMI system capable of scaling to 64 measurement axes.

Which ZYGO lasers are compatible with the 4104C?

ZYGO lists 7702, 7714, and 7724 as compatible laser platforms for the 4104(C) family.

Do not select a laser solely by connector compatibility. The optical configuration and interferometer arrangement must also match.

Is ZMI-4104C a PLC or DCS I/O module?

No. It is precision measurement electronics for an optical interferometer system. Although it can be integrated into a larger automated motion-control architecture, its primary job is nanometer-scale displacement measurement, not conventional PLC/DCS signal processing.

Can ZMI-4004 replace ?

Not as a blind substitution. Both are four-axis ZMI measurement boards, but they belong to different generations/families and can have different system, software, and performance requirements. ZYGO separately identifies the 4004 and 4104(C) measurement boards.

For an installed system, verify the host VME chassis, software, laser/interferometer configuration, synchronization requirements, and required measurement performance before approving the 4004 as an alternative.

What should I request when buying a refurbished ?

Ask for:

• Actual front and rear board photographs
• identification
• PCB revision and serial number
• VME connector inspection
• Power-on/initialization test
• VME bus communication test
• Four-channel functional test
• Known-good compatible laser/interferometer test
• Optical signal verification
• Displacement measurement verification
• Synchronization test where applicable
• Firmware/software compatibility information
• ESD-safe packaging
• Warranty terms

For this board, a seller’s statement that it “powers on” has limited value. The meaningful test is whether the four measurement channels process a known optical interferometer signal and return stable displacement data.