Product Overview

The Agilent HP 5517B is a two-frequency helium-neon laser head used in laser interferometer systems for high-precision displacement and velocity measurement. It generates a continuous-wave, heterodyne laser beam and provides a reference frequency to the associated interferometer electronics. The 5517B is intended for VME- and PC-based measurement systems and applications such as machine-tool metrology, where measurement velocity requirements are moderate. Agilent documentation specifies a nominal vacuum wavelength of approximately 632.991 nm, a 1.9–2.4 MHz reference frequency, and a typical 6 mm beam diameter. The laser head is a Class II laser product and requires ±15 VDC power.

Technical Specifications — HP 5517B

The reference frequency and velocity specifications are confirmed by current Keysight documentation, while the detailed Agilent manual provides the laser, electrical, and physical characteristics.

Agilent HP 5517B

Key Features and Benefits — HP 5517B

• Two-frequency heterodyne laser architecture
• Stable 632.991 nm nominal wavelength
• 1.9–2.4 MHz reference frequency
• 6 mm nominal measurement beam
• Suitable for precision displacement measurement
• Designed for VME and PC interferometer systems
• Compatible with the Keysight/Agilent interferometry ecosystem
• Useful for machine-tool calibration and dimensional metrology
• Provides a differential TTL-level reference signal

The higher reference frequency of this series allows faster measurement motion than earlier 5517A configurations. For the 5517B, the specified maximum linear velocity with linear optics is 500 mm/s.

Related Models

Agilent 5517A: Earlier laser-head generation with a lower 1.5–2.0 MHz reference-frequency range.

Agilent 5517C: Higher-frequency version with a 2.4–3.0 MHz reference range and higher maximum linear velocity.

Agilent 5517D: Higher-speed model with a 3.4–4.0 MHz reference-frequency range.

Agilent 5517BL: Vented version of the 5517B designed for applications requiring forced-air thermal management.

Installation and Maintenance — HP 5517B

Before replacement, verify the laser-head model, beam height, optical alignment, receiver type, power supply, and interferometer electronics. The ±15 VDC supply must remain within the specified tolerance, and the optical path should be kept clean and properly aligned.

Allow the laser head to reach thermal stability before precision measurements. Agilent documentation notes that wavelength and optical-power performance should be evaluated after stabilization, while the current Keysight specification lists a 90-minute warm-up period.

Personally, I would check optical output power before condemning an older unit. A laser can remain operational while its output gradually declines, yet the reduced optical power may eventually affect measurement-system integrity.

Product Warranty — HP 5517B

Warranty coverage depends on supplier, equipment condition, calibration status, and purchase agreement. For used or refurbished units, confirm laser output power, reference-frequency stability, optical condition, calibration history, power-supply performance, and functional-test results before purchase.

The Agilent HP 5517B remains a useful maintenance spare for compatible laser interferometer systems. Its optical wavelength, reference frequency, beam height, power requirements, and receiver compatibility should be matched carefully before installation.