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SR540 Optical Chopper System

SR540 Optical Chopper System
SR540 Optical Chopper System
  • 4 Hz to 3.7 kHz chopping frequencies
  • Low phase jitter
  • Single and dual beam experiments
  • Sum & difference reference outputs
  • Bolt clamp or rod mounting
SR540 specifications

The SR540 chopper will handle all your optical chopping requirements—from simple measurements to dual-beam and intermodulation experiments. The SR540 has a 4-digit frequency display, front-panel frequency control, analog voltage frequency control and two reference outputs with selectable operating modes. Two anodized aluminum blades are provided: a 5/6 slot blade for frequencies up to 400 Hz, and a 25/30 slot blade for frequencies up to 3.7 kHz. Reference outputs are provided for frequencies corresponding to each row of slots, as well as the sum and difference frequencies.

SR540 Front Panel Front Panel
SR540 Rear Panel Rear Panel

Optical Chopper Applications

Single-Beam Experiment

In this application, a single optical beam is chopped by the outer row of slots, and the reference output from the right BNC is used to lock the lock-in amplifier to the chop frequency. The inner row of slots could also be used, in which case the left BNC would be the reference output. In either case, the REFERENCE MODE switch is in the “up” position.

Single Beam Experiment
Single Beam Experiment

Dual-Beam Experiment

In this arrangement, the output from a single source is split and chopped at two different frequencies by the two rows of chopper slots. One beam passes through the experiment while the other is used as a reference beam. The beams are recombined and sent to the same detector. Two lock-ins are used to detect the signals at ƒinner, corresponding to the experimental signal, and ƒouter, corresponding to the reference beam. If the detected signal in the experimental arm is ratioed to the detected signal in the control arm, then effects due to changing source intensity and detector efficiency are removed.

Dual Beam Experiment
Dual Beam Experiment

*Related Products* SR510/530 Lock-in Amplifiers SR810/830 DSP Lock-in Amplifiers SR850 DSP Lock-in Amplifiers

SR540 Specifications

 
General
Chop frequency 4 Hz to 400 Hz (5/6 slot blade)
400 Hz to 3.7 kHz (25/30 slot blade)
Frequency stability 250 ppm/°C (typ.)
Frequency drift <2 %, 100 Hz < f < 3700 Hz
Phase jitter (rms) 0.2° (50 Hz to 400 Hz)
0.5° (400 Hz to 3.7 kHz)
Frequency display 4-digit, 1 Hz resolution and accuracy
Frequency control 10-turn pot with 3 ranges:
4 Hz to 40 Hz
40 Hz to 400 Hz
400 Hz to 3.7 kHz
Input control voltage 0 to 10 VDC for 0 to 100% of full scale. Control voltage overridesfrequency dial.
Reference modes ƒinner, ƒouter, 5 × ƒouter, ƒinner + ƒouter, ƒouter - ƒinner
Dimensions Controller: 7.7" × 1.8" × 5.1" (WHL)
Chopper head: 2.8" × 2.1" × 1.0" (WHL)
Blade diameter 4.04" ±0.002"
Cable length 6 ft.
Power 12 W, 100/120/220/240 VAC, 50/60 Hz
Warranty One year parts and labor on defects in materials and workmanship, 90 days on motor.