HP 81524A InGaAs Optical Head, 800–1650 nm, +3 to -90 dBm

HP 81524A InGaAs Optical Head, 800–1650 nm, +3 to -90 dBm

The HP 81524A Optical Head is a precision optical power sensor designed for professional fiber optic, telecom, photonics, laboratory, and production measurement applications. It uses a 5 mm InGaAs detector and provides optical power measurements across wavelengths from 800 nm to 1650 nm.

The HP 81524A offers a broad optical power range from +3 dBm to -90 dBm. It supports parallel-beam measurements and compatible connectorized fibers, including fiber sizes from 9/125 µm to 100/140 µm with numerical aperture up to 0.3. This flexibility makes the optical head useful for single-mode and multimode optical test setups when the launch conditions and coupling arrangement are appropriate.

The optical head requires an HP 81533B Optical Head Interface Module and a compatible lightwave multimeter mainframe for operation. The interface module connects the external optical head to the measurement system and provides the required signal processing, display, power, and control functions. The HP 81524A does not operate as a standalone optical power meter.

Features and Benefits of the HP 81524A Optical Head

The HP 81524A provides practical optical measurement performance for engineers, technicians, laboratories, production facilities, and service organizations working with visible-near-infrared and telecom-wavelength optical systems.

• InGaAs detector: Uses a 5 mm InGaAs sensor element for optical power measurements from 800 nm to 1650 nm.
• Wide optical power range: Measures optical signals from +3 dBm down to -90 dBm.
• Broad wavelength coverage: Supports applications across near-infrared and common telecom wavelength regions.
• Parallel-beam measurement: Supports free-space measurements using a properly aligned parallel optical beam.
• Fiber measurement compatibility: Supports compatible fibers from 9/125 µm to 100/140 µm with numerical aperture up to 0.3.
• High measurement resolution: Provides 0.001 dB or dBm display resolution and optical power resolution from 0.01 pW to 10 pW, depending on the measurement range.
• Low optical noise: Provides peak-to-peak noise below 5 pW under the specified conditions.
• Defined linearity performance: Supports consistent optical power measurements across a broad dynamic range.
• Modular system integration: Operates with the HP 81533B Optical Head Interface Module and a compatible HP or Agilent lightwave multimeter.
• Compact cylindrical format: Suitable for optical benches, laboratory fixtures, production stations, and configurable fiber optic test systems.

Broad Optical Power Measurement Range

The HP 81524A provides an optical power range from +3 dBm to -90 dBm. This allows the sensor to measure relatively strong optical signals as well as low-level power encountered during component loss testing, fiber link evaluation, receiver-path measurements, and laboratory characterization.

The wide measurement range is useful when a test procedure includes substantial changes in optical power. For example, the same optical head may be used to measure a source directly and then measure the reduced signal after it passes through a fiber link, attenuator, coupler, switch, or passive optical component.

The measurement range and resolution are managed through the compatible lightwave multimeter and optical head interface module. Optical power resolution varies from 0.01 pW to 10 pW depending on the power range selected by the system.

InGaAs Detector Performance

The HP 81524A uses an InGaAs detector for measurements from 800 nm to 1650 nm. This wavelength coverage includes common fiber optic test regions around 850 nm, 1310 nm, and 1550 nm, subject to the applicable fiber, coupling, accuracy, and operating conditions.

The head provides uncertainty of ±2.2% from 1000 nm to 1600 nm under the specified reference conditions. Total uncertainty is specified at ±4% ±5 pW from 1000 nm to 1600 nm under the defined operating conditions.

For measurements across the full supported wavelength range, an additional uncertainty contribution applies. Measurement accuracy also depends on source stability, spectral width, beam position, fiber numerical aperture, connector condition, calibration age, ambient temperature, and the complete optical coupling arrangement.

Fiber-Coupled and Free-Space Applications

The HP 81524A can receive a parallel optical beam or signals from compatible connectorized fibers. The applicable fiber range extends from 9/125 µm through 100/140 µm with numerical aperture up to 0.3.

Reference measurements use a parallel beam with a 3 mm spot diameter centered on the detector. Connectorized fiber measurements with numerical aperture up to 0.2 are also supported under the stated operating conditions. Fiber applications with numerical aperture between 0.2 and 0.3 require appropriate lenses and have an additional specified uncertainty contribution.

The correct lens or connector adapter may be required for a particular fiber setup. Buyers should confirm the supplied adapter or lens configuration because these accessories determine how the optical signal is coupled onto the detector.

Typical Applications

The HP 81524A InGaAs Optical Head is suitable for professional applications such as:

• Fiber optic optical power measurement
• Single-mode and multimode source evaluation
• Insertion-loss measurement
• Optical component characterization
• Laser and LED source testing
• Fiber link verification
• Optical switch and attenuator testing
• Telecom laboratory measurements
• Photonics research and development
• Production testing and quality control
• Free-space optical power measurement
• Service, repair, and replacement-sensor requirements

Product Overview

Optical Specifications

Linearity Specifications

The following linearity specifications apply over an optical power range from +3 dBm to -70 dBm. Performance is defined under constant-temperature conditions.

Reference and Operating Conditions

The specified reference uncertainty is based on a continuous-wave power level of 10 µW, equivalent to -20 dBm, with a parallel beam having a 3 mm spot diameter centered on the detector. Reference conditions also include an ambient temperature of 23 °C ±5 °C, calibration-age requirements, and a source spectral width below 10 nm.

Operating conditions permit a centered 3 mm parallel beam or compatible connectorized fiber with numerical aperture up to 0.2. For fiber applications with numerical aperture from 0.2 to 0.3, a suitable lens is required and an additional 0.5% uncertainty applies within the specified 850 nm, 1300 nm, and 1550 nm regions.

An additional 1% should be added to total uncertainty when measurements extend across the complete wavelength range rather than the stated accuracy range. Outside the specified low-noise wavelength range, noise may increase above the listed value.

Compatible Interface and Measurement System

The HP 81524A requires an HP 81533B Optical Head Interface Module. The interface module installs in a compatible lightwave multimeter and provides the electrical interface between the optical head and the measurement mainframe.

When operated through a compatible system, the optical head supports optical power display in dBm, dB, or watts according to the available mainframe functions. Resolution and acquisition functions are controlled by the optical head interface and host instrument.

The HP 81533B interface module, host lightwave multimeter, detector lenses, connector adapters, and optical cables should not be assumed to be included unless specifically identified in the product listing.

Environmental and Mechanical Specifications

Measurement Preparation and Sensor Care

The HP 81524A should complete its recommended 20-minute warm-up period before precision measurements. The optical power meter should be zeroed according to the applicable operating procedure, particularly before low-level measurements.

The detector window, lens, connector adapter, and fiber end faces should be inspected and kept clean. Dust, residue, scratches, fingerprints, or damaged connectors can introduce power loss, instability, and measurement errors.

For free-space measurements, the optical beam should be centered on the detector and maintain the required spot diameter. For fiber measurements, the correct lens or connector coupling arrangement should be used for the fiber type and numerical aperture.

The detector surface should not be touched directly. Cleaning should be performed only with methods and materials appropriate for optical detector windows and precision optical surfaces.

Calibration and Testing Before Shipment

When calibration is technically applicable and supported, the HP 81524A is calibrated before shipment. The calibration process may include verification of optical power response, linearity, wavelength-dependent sensitivity, noise performance, and operation with a compatible HP 81533B Optical Head Interface Module.

Following successful calibration, the optical head may include a calibration label, calibration certificate, and related calibration data, depending on the equipment and calibration service. The recommended recalibration period specified for the HP 81524A is two years.

If formal calibration is unavailable or not applicable to the specific optical head, the unit receives comprehensive functional and performance testing. This process may include detector-response evaluation, low-level and higher-level optical power checks, cable and connector inspection, interface-module recognition, zeroing, and measurement stability testing.

This testing helps verify that the equipment operates correctly and that its available functions have been evaluated before it is released for shipment. The exact calibration scope, documentation, test data, and included service records should be confirmed before purchase when these items are required for laboratory, production, regulatory, or quality-management applications.

Buyer Considerations

The HP 81524A is an external optical head and requires the HP 81533B Optical Head Interface Module and a compatible lightwave multimeter. Buyers should confirm that the necessary interface module and host instrument are available before purchase.

Buyers should review the condition of the detector window, sensor housing, connecting cable, interface connector, installed lens or adapter, calibration status, and service history. Detector lenses and connector adapters may affect fiber compatibility and measurement uncertainty.

The HP 81524A should not be confused with the HP 81525A high-power InGaAs optical head. The 81524A provides greater low-level sensitivity with a +3 dBm to -90 dBm range, while the 81525A is intended for substantially higher optical input levels.

Why Buy from AssetRelay?

AssetRelay supplies professional equipment and product solutions for fiber optic, telecom, laboratory, production, inspection, cleaning, RF/microwave, electronic test, and photonics applications. The HP 81524A InGaAs Optical Head is listed to help engineers, laboratory personnel, production facilities, procurement teams, and service organizations source professional optical power measurement equipment.

Buyers should review the available product photographs, detector condition, installed lens or adapter, cable condition, included accessories, calibration information, and interface compatibility before purchase. Confirming these details helps ensure that the optical head matches the intended wavelength, optical power range, fiber type, beam geometry, and measurement platform.

Only accessories specifically identified in the product listing should be considered included. The HP 81533B interface module, lightwave multimeter mainframe, optical lenses, connector adapters, patch cables, cleaning supplies, and calibration accessories may be required separately.