The Stanford Research Systems SR540 Optical Chopper Controller is a precision instrument that modulates optical signals by periodically interrupting a light beam. It delivers chopping frequencies from 4 Hz to 3.7 kHz across two interchangeable blade configurations, making it ideal for single-beam experiments, dual-beam ratio measurements, intermodulation studies, and spectroscopy. The controller provides stable frequency control with minimal phase jitter and includes selectable reference outputs for lock-in amplifier synchronization.
Technical Specifications
Frequency Range & Stability
• 4 Hz to 400 Hz (5/6-slot blade)
• 400 Hz to 3.7 kHz (25/30-slot blade)
• Frequency stability: 250 ppm/°C (typical)
• Frequency drift: <2% across 100 Hz to 3700 Hz
Phase Jitter
• 0.2° rms (50 Hz to 400 Hz)
• 0.5° rms (400 Hz to 3.7 kHz)
Control & Display
• 4-digit display with 1 Hz resolution and accuracy
• 10-turn potentiometer with three selectable ranges (4–40 Hz, 40–400 Hz, 400 Hz–3.7 kHz)
• Analog voltage control: 0–10 VDC for 0–100% full scale (overrides front-panel dial)
Reference Outputs (two BNC ports, selectable modes)
• f_inner (inner row frequency)
• f_outer (outer row frequency)
• 5 × f_outer
• f_inner + f_outer (sum frequency)
• f_outer – f_inner (difference frequency)
Power: 12 W, 100/120/220/240 VAC, 50/60 Hz
– Key Features
• Dual interchangeable blades for extended frequency coverage
• Low phase jitter enables high-sensitivity lock-in detection
• Bolt clamp or rod mounting for flexible optical bench integration
• Blade diameter: 4.04" ± 0.002"
• 6 ft cable length
– Typical Applications
• Single-beam experiments with lock-in amplifier synchronization
• Dual-beam experiments for intensity-ratio measurements and source/detector drift compensation
• Intermodulation and advanced modulation schemes
• Spectroscopic analysis with modulated light sources
– Compatibility & Integration
Replacement blade options include 25/30 dual-slot blade (P/N: O5402530), 5/6 dual-slot blade (P/N: O54056), and 5-slot replacement blade (P/N: O5405).
