The Keysight N1225A is a four-channel laser axis board for VME bus systems that delivers sub-nanometer position resolution using fiber optic receivers and laser interferometry. Each board measures distance with 0.15 nm resolution using plane mirror optics, and firmware revision B.40 enables optional 0.039 nm LSB resolution. Up to 31 axes can be supported through multiple board interconnection. The unit features an oscilloscope-like data capture accessible via web browser, 10/100 BaseT Ethernet connectivity, and DHCP network support.
Technical Specifications
Position Measurement
• Resolution: 0.15 nm (plane mirror); 0.039 nm LSB optional (B.40 firmware); 0.3 nm, 0.6 nm, 1.2 nm, 2.4 nm, 4.8 nm also available
• Working range: ±10.3 m
• Maximum velocity: ±2.29 m/s (15 MHz split laser head); ±1.1 m/s (7.5 MHz split laser head)
• Maximum acceleration: 400 g
• Position update rate: 10 MHz
• Receiver sensitivity: 0.065 µW
Optical Input
• Four measurement channels per board
• Frequency range: 500 kHz to 30 MHz
• Maximum input levels: 62.5 µW AC power; 187 µW DC power
• Dynamic range: 1250:1 maximum; 93.5:1 minimum
• Signal strength voltage update rate: 100 Hz typical per channel
Electrical
• Power supply: +5V single rail
• Maximum current: 5.6 A
• VME/VME64x compatible, A16/A24 addressing, D16/D32 data cycles
Output & Interface
• 36-bit parallel position word on P2 connector at 10 MHz/(number of axes)
• Four ST-type optical input connectors
• One digital reference output; optical reference input on Channel 4
• 10/100 BaseT Ethernet with DHCP and web server
– Key Features
• Four simultaneously sampled channels eliminate cross-coupling errors
• Scalable to 31 axes via multiple board configuration
• 36-bit position register provides ±10.3 m working range
• Sub-microwatt receiver sensitivity for long fiber runs
• Programmable resolution from 0.039 nm to 4.8 nm LSB
– Typical Applications
• High-precision industrial positioning systems
• Semiconductor equipment requiring sub-micron measurement
• Multi-axis motion control in research instrumentation
• Real-time distance monitoring in vibration-sensitive environments
– Compatibility & Integration
The N1225A integrates into existing VME backplane infrastructure and supports both analog optical and digital reference inputs. Built-in Ethernet enables remote monitoring and firmware updates via standard web browsers.
