The HP/Agilent 5501B is a two-frequency helium-neon laser head engineered for high-precision metrology and interferometry systems. This continuous-wave (CW) source delivers 180 µW to 1 mW of optical power at 632.991 nm with exceptional wavelength stability and accuracy. The 5501B automatically maintains frequency lock for reliable performance in demanding measurement applications requiring sub-ppm stability over extended operational lifetimes.
Technical Specifications
Optical Output
• Wavelength: 632.991 nm (vacuum wavelength: 632.991372 nm)
• Beam power: 180 µW (minimum) to 1 mW (maximum)
• Beam diameter: 6 mm typical
• Wavelength accuracy: ±0.1 ppm (3 sigma, lifetime)
• Wavelength stability: ±0.002 ppm (1 hour typical); ±0.02 ppm (lifetime typical)
• Reference frequency: 1.55 MHz to 2.4 MHz (varies by unit configuration)
Electrical Requirements
• Supply voltage: +15 V ±0.3 V at 0.79 A max; −15 V ±0.3 V at 0.67 A max
• Operating power: 23 W
• Warmup power: 35 W
• Laser tube anode: 1.2 kV to 12 kV DC
Physical & Environmental
• Weight: 3.4 kg (7.5 lb)
• Warmup time: <10 minutes (5 minutes typical)
• Magnetic field (non-operating): <5.25 milligauss at 4.6 m distance
• Cabling clearance: 10.16 cm (4 in) recommended
– Key Features
• Class II laser product (21 CFR 1040.10/1040.11 compliant)
• Two-frequency CW output for interferometric applications
• Automatic frequency stabilization
• Sub-0.002 ppm short-term stability
• Safety Class I electrical design with protective earth terminal
– Typical Applications
• Laser interferometry and displacement measurement
• Precision positioning and calibration systems
• Advanced metrology instrumentation
• Applications demanding ppm-level wavelength accuracy
– Compatibility & Integration
The 5501B integrates into systems requiring dual-frequency laser sources with stable, locked optical output. Dual ±15 V supplies and thermal stabilization circuits are required. High voltage hazard present; service restricted to trained personnel.
