ZYGO ZMI-7705 Dual-Frequency He-Ne Laser Head for Displacement Interferometer

1. Product Description

ZMI‑7705 (Full PN: 8070‑0902‑0X) is ZYGO’s entry-level Zeeman-split dual-frequency He-Ne laser head of ZMI series, specially matched with ZMI 501A compact measurement electronics to build 1–2 axis high-precision laser interferometer displacement measurement systems. It adopts air-cooled compact design, Class II laser safety grade, for small precision motion platforms requiring nanometer-level position feedback.

• Core Optical & Electrical Specs        
  Light Source: Helium-Neon (He-Ne) 632.8nm red laser;        
  Frequency Split: 3.6 MHz Zeeman splitting;        
  Output Optical Power: >250 µW;        
  Beam Diameter: 4 mm;        
  Frequency Stability (3σ, 1 hour): 10 ppb;        
  Heat Dissipation: 7 W, natural air cooling (no water cooling);        
  Laser Safety Class: Class II;        
  Optical Isolation: Not integrated, requires external isolator for high-reflection optical paths.
• System Matching Rule: Exclusive pairing with ZMI 501A measurement unit, maximum support for 2 independent measurement axes; incompatible with ZMI 2400/4004 high-speed multi-axis boards (those use 7702/7714/7724 lasers).
• Mechanical Structure: Integrated sealed metal laser cavity housing, built-in temperature stabilization circuit; standard optical fiber collimation output interface, industrial mounting holes for fixed installation on lithography/metrology equipment frames.
• Measurement Performance Matching (with 501A): Double-pass interferometer resolution 1.24 nm, maximum measurable speed ±0.475 m/s, positioning repeatability σ=1.6 nm.
• Operating Environment: Working temperature 18–28°C (constant temperature lab recommended); storage -20°C ~ +60°C; humidity 10–80% non-condensing.
• Application Positioning: Cost-effective compact laser source for low-to-medium speed single/dual-axis precision positioning, balancing precision and equipment footprint.

2. Core Product Functions

• Dual-Frequency Laser Output for Heterodyne Interferometry: Generates two orthogonally polarized frequency-shifted laser beams, heterodyne beat signal enables high linearity displacement calculation without signal saturation, realizing nanometer linear position measurement.
• Cavity Temperature Stabilization: Built-in constant temperature control circuit to stabilize laser wavelength, suppress wavelength drift caused by ambient temperature fluctuations, guarantee long-term measurement accuracy.
• Compact Multi-Axis Measurement Support: Matched with 501A signal processing unit to realize simultaneous 2-axis linear displacement measurement, suitable for XY two-dimensional precision motion stages.
• Real-Time Optical Beat Signal Transmission: Transmits stable 3.6MHz beat frequency optical signal to measurement electronics, converts optical phase difference into digital displacement, velocity and acceleration data.
• Laser Self-Health Monitoring: Internal photodiode monitors laser output power; outputs power loss alarm signal to 501A unit when beam attenuation exceeds threshold, to prevent invalid measurement.

• Standard Industrial Signal Interface: Dedicated signal cable connects laser head to 501A measurement box, outputs power status, laser ready and fault alarm digital signals to upper motion control systems.

3. Typical Application Scenarios

• Semiconductor packaging equipment, small wafer XY precision positioning stages requiring dual-axis nanometer feedback.
• Optical metrology lab coordinate measuring machines (CMM), linear scale calibration platforms.
• Precision laser processing equipment: small laser cutting, laser marking high-precision motion axes.
• Optical component testing stages, lens grinding and polishing precision feed systems.
• Maintenance spare replacement for existing ZMI 501A+7705 interferometer measurement stations to restore positioning feedback.

4. Common Issues & Troubleshooting