Optical Chopper

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Optical Chopper
SR540 — Single & dual beam chopper

SR540 ... from $1695

Optical Chopper
SR540 — Single & dual beam chopper

BUY / QUOTE

SR540 ... from $1695

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

4 Hz to 3.7 kHz range
Low phase jitter
Single & dual beam experiments
Sum & difference outputs
Bolt clamp or rod mounting

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 Optical Chopper

Single-Beam Experiment

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.

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.

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 ƒ_inner, corresponding to the experimental signal, and ƒ_outer, 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.

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 overrides frequency dial.
Reference modes	ƒ_inner, ƒ_outer, 5 × ƒ_outer, ƒ_inner + ƒ_outer, ƒ_outer - ƒ_inner
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.