The HP/Agilent 81525A is a high-power InGaAs optical head designed for precise optical power measurements across the near-infrared spectrum. Built around a 5 mm InGaAs detector element, this optical head delivers measurement accuracy of ±3.0% across 900 nm to 1600 nm and handles power levels from –70 dBm to +27 dBm, making it suitable for both low-level and high-power optical signal characterization. The head exhibits low polarization-dependent loss and high return loss, critical for accurate testing of optical components and systems.
## Technical Specifications
• **Sensor Type:** InGaAs
• **Detector Area:** 5 mm
• **Wavelength Range:** 800 nm to 1650 nm
• **Power Measurement Range:** –70 dBm to +27 dBm (1250–1650 nm); –70 dBm to +23 dBm (800–1250 nm)
• **Measurement Accuracy:** ±3.0% (900–1600 nm)
• **Wavelength Accuracy:** ±3.0% (900–1600 nm)
• **Polarization Sensitivity:** Low PDL
• **Return Loss:** High
• **Warm-up Time:** 15 minutes
• **Recalibration Interval:** 1 year
• **Physical Dimensions:** 50 mm diameter × 30 mm length
• **Net Weight:** 0.1 kg
## Key Features
• 5 mm detector element optimized for high-power measurements
• Wide spectral coverage from 800 nm to 1650 nm
• Dynamic range spanning seven decades of optical power (–70 to +27 dBm)
• Low PDL and high return loss for demanding optical test applications
• Attenuation at 850 nm printed on lens; calibration entry via CAL parameter required for precise measurements
• Multiple connector interface options available
## Typical Applications
• Optical power measurement in fiber-optic communication systems
• High-power signal characterization
• Optical component and subsystem testing
• Low and high dynamic range power monitoring
## Compatibility & Integration
The 81525A integrates with HP/Agilent mainframe units including the 8153A, 8163, 8166, 8163A, and 8164A through interface modules 81533A or 81533B.
**Product Status:** Obsolete. No longer sold by Keysight; replacement model is the Keysight 81626B High Power Optical Head.
