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> Eg&g princeton 5210 high perf. phase lock-in amplifier
Eg&g princeton 5210 high perf. phase lock-in amplifier
EG&G PRINCETON Applied Research model 5210
High Performance Dual Phase Analog
Lock-in Amplifier W/Manual!!!!
X,Y, (%): X,Y, (V): R,q, Noise
0 to 2 V rms (1 mV steps) - manual or via command
The instrument includes a current preamplifier with two transimpedance settings and so can directly measure signals from current sources such as photodiodes. With an input impedance of down to typically only 25 W the resulting voltage generated across the source by the signal current is minimized for the very best performance.
The model 5210 uses a modified form of switching demodulator, known as the Walsh demodulator, which multiplies the applied signal by a stepped approximation to the reference sinusoidal waveform. This gives a demodulator that does not respond to signals at the third and fifth harmonics, although it does respond to higher harmonics. A fourth-order signal channel filter is therefore included to reject these harmonics, giving a overall sinewave response. The advantages of the switching demodulator are thereby retained without the phase and magnitude errors associated with the use of highly selective filters.
The instrument can be switched to operate in either sinewave or squarewave mode, giving you the choice of the optimum detection method for your experiment.
The output low-pass filters offer time constants in the range 1 ms to 3 ks, with all settings available at slopes of both 6 and 12 dB/octave. In addition, the units include a rear-panel output giving the signal at the output of the in-phase (X-channel) demodulator with a time constant of typically only 100 s, for use in those applications such as tandem demodulation where the largest output bandwidth is required.
The analog outputs from the demodulators, after filtering by the output low-pass filters, need to be digitized by an analog to digital converter (ADC) for display or for transfer to the controlling computer. If this conversion is carried out asynchronously then the resulting values can display significant jitter. This is because the demodulator output contains not only the required DC level, but also signals at twice the reference frequency. When the output is sampled for conversion, this 2F signal means that some samples will be smaller and some larger than the mean.
Of course, the 2F component can be reduced to any arbitrarily small value by increasing the time constant, but this reduces the response time to changes in input signal, slowing down data throughput. The model 5210 therefore offers a unique reference synchronous ADC trigger mode, which guarantees that the output is sampled at the same point relative to the reference waveform and thereby removes this source of error.
Compatible LabVIEW drivers are available for those researchers working in that environment while the unit is also supported by the SRInstComms ActiveX control and SDK. It can also be used with our Acquire data acquisition software package, which allows non-programmers an easy way to log the instrument outputs to a PC file.
