Electrical Measurement：Weak Signal Measurement (Preamplifier, Lock in Amplifier etc.)

Chopping frequency 0.4 Hz to 20 kHz, synchronizable with external signals.
Precision Optical Chopper SR542
SR23

Stanford Research Systems
Low jitter optical chopper
SR540 Optical chopper
SR17

Stanford Research Systems
No moving parts, Minimal heat generation, Wide acceptance angle
High Speed Optical Chopper
HN11

HINDS Instruments
Accurately measures small DC currents in electron beam, ion beam, mass spectrometry, etc. at high sampling rates
USB Picoammeter
RBD01

RBD Instruments, Inc.