Stanford Research Systems SR865 lock-in amplifier

The Stanford Research Systems SR865 lock-in amplifier delivers precise measurement of small AC signals in noisy environments across a 1 mHz to 2 MHz frequency range. Built on advanced digital signal processing, the instrument achieves noise performance of 2.5 nV/√Hz at 1 kHz and accepts voltage inputs from 1 nV to 1 V or current inputs from 1 fA to 1 µA sensitivity. The SR865 supports both single-ended and differential voltage input configurations with 10 MΩ + 25 pF impedance, and offers flexible current input paths with 1 kΩ or 100 Ω termination to virtual ground.

– Technical Specifications

Input Specifications
• Voltage inputs: single-ended or differential, AC or DC coupled
• Voltage input range: 10 mV to 1 V peak
• Current input range: 10 nA or 1 µA peak
• Input impedance: 10 MΩ + 25 pF (voltage); 1 kΩ or 100 Ω to virtual ground (current)
• Gain accuracy: ±1% below 200 kHz; ±2% to 2 MHz
• Noise: 2.5 nV/√Hz at 1 kHz (10 mV input range, typical)
• Harmonic distortion: –80 dB below 100 kHz; –60 dB to 2 MHz

Frequency & Response
• Operating range: 1 mHz to 2 MHz
• Time constants: 1 µs to 30 ks
• Filter rolloffs: 6, 12, 18, and 24 dB/octave

Reference & Detection
• Internal reference: 0.001 Hz to 2 MHz user-defined
• External reference: sine or square wave, 50 Ω or 1 MΩ termination
• Dual reference mode for double-modulated signal recovery
• Harmonic detection: fundamental through 99th harmonic
• Chop mode for SR540 Optical Chopper synchronization

Outputs
• X and Y: ±10 V full scale, 50 Ω
• R and θ: ±10 V full scale, 50 Ω
• BlazeX auxiliary output: <2 µs delay
• CH1 and CH2 outputs with signal monitor

– Key Features

• Touchscreen interface for intuitive operation
• Low-noise input amplifiers
• Digital filters for reduced measurement time and improved SNR
• Flexible signal recovery in demanding measurement environments

– Typical Applications

• Materials characterization and impedance spectroscopy
• Noise floor analysis in sensitive measurements
• Phase-locked detection in modulated signal recovery

– Compatibility & Integration

BlazeX rear-panel connectivity supports low-latency integration with external instrumentation. Auxiliary inputs enable custom signal conditioning chains.