The SR124 design follows two basic themes. First, the signal path is entirely built from low-noise analog electronics: the best JFETs, transistors, op-amps, and discrete components. Second, configuration control is managed by a microcontroller whose system clock only oscillates during the brief moments needed to change gains or filter settings. This “clock-stopping” architecture eliminates the inconvenience and reliability issues associated with mechanical panel controls, and makes full remote operation of the SR124 possible.

Don’t let the numeric displays fool you — the SR124 really stops all digital clocks during operation. The numeric displays show precision setting information, such as input filter frequency, demodulator phase shift, and source output amplitude. The drive electronics are completely static, with no “scanning” or refresh to generate the slightest interference.

Whenever the microcontroller becomes active, the “CPU Activity” indicator illuminates, clearly showing when the digital clock is running. This occurs in response to front-panel button presses or remote computer commands.

The fast rise time, low noise, and excellent DC accuracy of the SR445A make it an ideal instrument for amplifying the outputs of fast photomultiplier tubes and photodiodes.

• 4 independent channels
• DC to 350 MHz bandwidth
• 1 ns rise/fall time
• 6.4 nV/√Hz input noise
• Voltage gain to 625
• 50 Ω input and output impedance
• 3 ns overload recovery
• Excellent phase linearity

Both the single phase SR510 and the dual phase SR530 have low-noise voltage and current inputs, high dynamic reserve, two stages of time constants, and an internal oscillator. In addition, both lock-ins come equipped with a variety of features designed to make them simple to use.

• 0.5 Hz to 100 kHz frequency range
• Current and voltage inputs
• Up to 80 dB dynamic reserve
• Tracking band-pass and line filters
• Internal reference oscillator
• Four ADC inputs, two DAC outputs
• GPIB and RS-232 interfaces

It is the ideal preamplifier for low-temperature synchronous detection applications where isolation between the experimental sample and the lock-in amplifier is critical.

• Transformer-coupled input
• 0.1 nV/√Hz input noise
• 0.1 Hz to 40 kHz bandwidth
• Gain of 100 or 500
• Single-ended and differential inputs
• >40 dB isolation from DC to 500 MHz
• Powered by SRS lock-in amplifiers

• 4 nV/√Hz input noise
• 1 MHz bandwidth
• Variable gain from 1 to 50,000
• AC or DC coupled
• Two configurable signal filters
• Differential and single-ended inputs
• Line or battery operation
• RS-232 interface

High gain and bandwidth, low noise, and many convenient features make the SR570 ideal for a variety of photonic, low temperature and other measurements.

• 5 fA/√Hz input noise
• 1 MHz maximum bandwidth
• 1 pA/V maximum gain
• Adjustable bias voltage
• Two configurable signal filters
• Variable input offset current
• Line or battery operation
• RS-232 interface

The SR830 simultaneously displays the magnitude and phase of a signal, while the SR810 displays magnitude only. Both instruments use digital signal processing (DSP) to replace the demodulators, output filters, and amplifiers found in conventional lock-ins.

• 1 mHz to 102.4 kHz frequency range
• >100 dB dynamic reserve
• 5 ppm/°C stability
• 0.01 degree phase resolution
• Time constants from 10 µs to 30 ks
• Auto-gain, -phase, -reserve and -offset
• Synthesized reference source
• GPIB and RS-232 interfaces

It provides uncompromised performance with a frequency range of 25 kHz to 200 MHz and up to 80 dB of drift-free dynamic reserve.

• 25 kHz to 200 MHz frequency range
• 80 dB dynamic reserve
• Time constants from 100 µs to 30 ks (6, 12, 18 or 24 dB/oct rolloff)
• "No Time Constant" mode (10 to 20 µs update rate)
• Auto-gain, -phase, -reserve and -offset
• Internal or external reference
• Two 16-bit DACs and ADCs
• GPIB and RS-232 interfaces

The SR850 boasts a number of significant performance advantages over traditional lock-in amplifiers-higher dynamic reserve, lower drift, lower distortion, and dramatically higher phase resolution.

• 1 mHz to 102.4 kHz frequency range
• >100 dB dynamic reserve
• 0.001 degree phase resolution
• Time constants from 10 µs to 30 ks (up to 24 dB/oct rolloff)
• Auto-gain, -phase, -reserve and -offset
• Data logging (up to 65k samples)
• Smoothing, curve fitting & statistics
• GPIB, RS-232 and 3.5" disk drive