Agilent 8156A — Overview
The Agilent 8156A is a rack‑mount, electronically programmable optical attenuator mainframe intended for automated test, R&D, and production environments. It provides fine, repeatable attenuation control for single‑mode and multimode fiber systems, supports front‑panel and remote control, and accepts modular optical connector interface modules to match DUT connector types.
Key specifications
| Attribute | Typical value / notes |
|---|
| Attenuation range | Up to 60 dB (configuration dependent) |
| Setting resolution | 0.001 dB |
| Wavelength coverage | Typical single‑mode range 1200 nm – 1650 nm (wavelength‑dependent accuracy) |
| Return loss (Option 101) | ≈45 dB (high‑performance, straight PC contacts) |
| Connector interfaces | Uses Agilent 81000xx interface modules (input and output required) |
| Monitor tap | Optional monitor tap available (requires third interface/module) |
| Control interfaces | GPIB (HP‑IB) and front‑panel control; programmable command set |
| Form factor | Rack‑mount mainframe (modular connector interfaces) |
Mechanical and optical interfaces
- The 8156A mainframe accepts 81000xx optical interface modules that provide the physical connector type (FC, SC, ST, DIN, biconic, etc.).
- Option 101 is the high‑performance single‑mode PC (straight optical contact) return‑loss upgrade; it is implemented by specifying the option on the mainframe and installing the appropriate 81000xx input/output modules.
- If a monitor tap is required, order the monitor option and a third interface module; monitor taps typically provide a fixed tap (for example, ~13 dB) routed to a separate connector.
Performance, calibration, and wavelength dependence
- Accuracy and repeatability are wavelength dependent; attenuation error tables and calibration procedures vary across the 1200–1650 nm range.
- For precision work, perform wavelength‑specific calibration and verify attenuation accuracy at the operating wavelengths.
- Return‑loss and back‑reflection behavior depend on both the option selected (PC vs APC) and the installed interface modules; Option 101 targets ~45 dB with straight PC contacts, trading slightly higher reflection than APC for broader compatibility.
Control, programming, and typical commands
- The instrument is controllable from the front panel and remotely via GPIB/HP‑IB.
- The programming manual provides commands to set attenuation in dB with 0.001 dB resolution, query current attenuation, and configure instrument options.
- Typical automated uses include attenuation sweeps, stepped attenuation for receiver sensitivity testing, and integration into production test sequences.
Use cases, tradeoffs, and ordering checklist
Use cases
- Automated receiver sensitivity and dynamic range testing.
- Production test where fine attenuation steps and repeatability are required.
- R&D experiments requiring programmable optical loss.