OE2021 Lock-in Amplifier

Overview

The OE2021 digital lock-in amplifier is the latest core technology product, featuring exceptional high performance and wide bandwidth measurement capabilities. This instrument is based on digital modulation technology and is equipped with a 24-bit high-precision analog-to-digital converter (ADC) and 16-bit high-speed digital-to-analog converter (DAC). With the newly launched LIUXI-architecture, it can accurately, quickly, and flexibly detect effective signal components hidden in strong noise.

The OE2021 is capable of simultaneously measuring the amplitude and phase information of input signals. It achieves international leading levels in key performance indicators such as measurement accuracy, operating frequency range, signal-to-noise ratio, and dynamic reserve. Additionally, the newly added multi-harmonic measurement, oscilloscope, spectrum analyzer functions, and PID control capabilities make the OE2021 widely applicable to various needs in scientific research and industrial fields.

Input Signal Channel

The OE2021 is equipped with a low-noise analog amplifier that efficiently processes single-ended or differential signals, with an equivalent input noise as low as 2.5 nV/√Hz. The input impedance of this channel is 10 MΩ, and the full-scale range is from 1 nVrms to 5 Vrms. Furthermore, the signal input channel uses a high-precision 24-bit ADC, achieving a dynamic range over 130 dB.

Output Signal Channel

The signal output ports of OE2021 is based on a 32 MSPS 16-bit DAC, capable of generating high-precision sine wave signals in the frequency range of 1 Hz to 1.5 MHz, with adjustable DC offset. The signal amplitude range is from 0.1 Vrms to 5 Vrms, and the DC offset range is ±5 Vdc. For external devices requiring bias voltage, such as electro-optic modulators, the OE2021 can drive devices directly without the need for additional level conversion amplifiers. The output signal phase is synchronized with the instrument's internal oscillator. It can be independently set for phase offset.

Additionally, the OE2021 supports AM/FM/PM modulation functions, allowing users to perform modulation control of the system.

Reference Signal Channel

The reference signal of the OE2021 can be selected as either a sine wave or square wave signal based on user requirements, or it can use an internally digitally synthesized reference signal. When the OE2021 is set to internal reference signal mode, the instrument's internal high-precision oscillator and digital synthesis algorithm generate a sine wave signal for multiplication with the input signal, with the internal reference signal being nearly unaffected by phase noise. Through digital phase shifting technology, the phase resolution of the internal reference signal can reach 1 μdeg.

When the OE2021 operates in external reference signal mode, it accepts sine wave signals or TTL logic levels as external reference signals, which are locked by the internal digital phase-locked loop. Based on the frequency of the reference signal, the OE2021 can detect signals at the fundamental frequency and its harmonics, detecting up to 10,000 times the fundamental frequency. But it provided that the maximum harmonic frequency does not exceed the upper limit of the instrument's measurement bandwidth.

Digital Demodulator

The OE2021 has 8 synchronized demodulators, which can be independently controlled. The time constant of the OE2021 can be flexibly set within the range of 100 ns to 3 ks, allowing users to customize the time constant according to their needs. The filter's roll-off rate can be selected from 6 to 48 dB/oct in 8 steps. Using digital modulation technology and advanced filter structures. The OE2021 offers higher dynamic reserve (>130 dB), more precise phase (absolute phase error < 1°), zero DC drift, and excellent orthogonal performance compared to traditional analog lock-in amplifiers. Additionally, the OE2021 provides an optional synchronous filter that can quickly eliminate the effects of signal harmonics, ensuring that the instrument accurately detects low-frequency signals while responding rapidly.

Color Display Screen

The OE2021 features a 5.6-inch TFT color display with a resolution of 640×480, serving as the main user interface, allowing full independent control of the instrument via  keyboard. On the display, users can easily heed parameters such as demodulator X, Y, R, θ, and configure various basic settings like filter constants, making the operation intuitive and convenient.

Communication Interface

The OE2021 includes USB 2.0, 1000 Mbps RJ45 Ethernet port, WIFI network interface, RS232 serial port, and GPIB interface. Through these interfaces, users can effectively utilize all testing functions of the OE2021 on a controlling computer, setting reasonable control parameters and reading the data measured by the instrument.

Input Signal Channel

Output Signal Channel

Reference Signal Channel

Oscillator

Demodulator

Auxiliary Inputs/Outputs

Communication Interfaces

Others

PC Software

The OE2021 provides professional PC software that allows configuration of each demodulator, input channel, and output channel through schematic diagrams or control panels, combining professionalism and practicality with simplicity and intuitiveness. The software features clear numerical display and real-time waveform display functions. Users can save the measurement results exportable as CSV files for subsequent analysis using professional software, enhancing the ease of testing. Furthermore, we fully support application programming interfaces (API) in Python, MATLAB, and LabVIEW.

Oscilloscope

The oscilloscope function features 2 signal channels, selectable for signal input, reference input, signal output, and auxiliary input/output, providing various triggering methods for real-time display of time-domain signals. Each channel has a maximum sampling depth of 65,536 and adjustable sampling durations from 65 µs to 1 s.

PID Controllers

The OE2021 has an internal independent 2-channel digital PID controller with a maximum sampling rate of 4 MSPS. The PID controller is closely linked with the lock-in amplifier, controlling the output signal's amplitude, phase, frequency, and other signals based on the measurements from the demodulator, achieving precise control of multiple parameters.

Parametric Scanner

The parameter scanner provides users with convenient quick scanning capabilities, allowing for the instant plotting of frequency response, amplitude response curves, and offering single or loop scanning modes.

FFT Spectrum Analyzer

The FFT spectrum analyzer analyzes the frequency domain information of signals based on waveforms captured by the oscilloscope. Depending on the sampling rate and sampling depth, the frequency resolution range of the spectrum analyzer is approximately 1 Hz to 31 kHz.