The Stanford Research Systems SR860 is a dual-phase lock-in amplifier designed for precision AC signal measurement across frequencies from 1 mHz to 500 kHz. With 120 dB typical dynamic reserve and input noise as low as 2.5 nV/√Hz at 1 kHz, it delivers exceptional sensitivity in high-noise measurement environments. The instrument accommodates both voltage and current inputs via switchable JFET-pair amplifiers with gains from 1 nV to 1 V and 1 fA to 1 µA respectively, supporting peak input levels up to 1 V and 1 µA. Detection extends to the 99th harmonic with selectable reference modes—internal, external sine/TTL, dual, and chop—enabling flexible synchronization strategies. A 640 x 480 touchscreen provides real-time visualization of up to four data channels with strip-chart and FFT capabilities. Output filtering includes 6, 12, 18, and 24 dB/octave roll-off options plus advanced Gaussian FIR and Phase-Linear filters. Time constants span 1 µs to 30 ks. The integrated precision oscillator generates sine waves with 6-digit frequency resolution and amplitude from 1 nV to 2 V plus ±5 V DC offset. Harmonic rejection reaches −80 dB; gain accuracy is ±1% below 200 kHz. A 10 MHz input/output timebase allows external synchronization and cascading of multiple units. Power consumption is 60 W; AC input accepts 100 V, 120 V, 220 V, or 240 V nominal at 50/60 Hz.
Technical Specifications
• Frequency Range: 1 mHz to 500 kHz
• Dynamic Reserve: 120 dB (typical)
• Voltage Input Noise: 2.5 nV/√Hz at 1 kHz; under 10 nV/√Hz at 10 Hz
• Current Input Noise: 130 fA/√Hz (1 µA range); 13 fA/√Hz (10 nA range)
• Input Impedance: 10 MΩ + 25 pF (voltage); 1 kΩ or 100 Ω (current, virtual ground)
• Sensitivity Range: 1 nV to 1 V (voltage); 1 fA to 1 µA (current)
• Max Input: 1 V peak (voltage); 1 µA peak (current)
• CMRR: 90 dB to 1 kHz (DC coupled, 10–100 mV range)
• Gain Accuracy: ±1% below 200 kHz
• Output Time Constants: 1 µs to 30 ks
• Filter Roll-off: 6, 12, 18, 24 dB/octave; Gaussian FIR and Phase-Linear filters
• Harmonic Detection: Fundamental through 99th harmonic
• Harmonic Rejection: −80 dB
• Oscillator Output: 1 nV to 2 V amplitude; ±5 V DC offset; 6-digit frequency resolution
• Timebase: 10 MHz input/output
• Display: 640 x 480 full-color touchscreen; up to 4-channel data visualization
• Power Consumption: 60 W
• AC Input: 100 V, 120 V, 220 V, or 240 V (50/60 Hz)
– Key Features
• Dual-phase lock-in detection with internal and external reference synchronization modes
• Dual reference mode for difference-frequency detection
• Chop mode PID controller output for SR540 Optical Chopper synchronization
• Selectable shield termination: 10 Ω (ground) or 10 kΩ (float)
• Current input bandwidth: 400 kHz (1 µA range) and 2 kHz (10 nA range)
• AC or DC coupling on voltage inputs
– Typical Applications
Precision AC signal recovery in physics, materials science, and engineering research where noise immunity and dynamic range are critical.
