Power, Local and Remote, Defaults | SRS Labs Lock-In Amplifier

should be allowed to approach a steady value before a reading is taken. For the 1 Hz ENBW, this time is on the order of 15 to 30 seconds; for the 10 Hz ENBW, the output stabilizes much faster. The noise output will vary slightly since there will always be noise variations that are slow compared to the bandwidth. Any DC component in the output will not contribute to the noise. However, a large DC output will cause the noise computation to initially rise to a large value before approaching the final answer. As a result, the computation will take longer to settle.

If the OVLD indicator is blinking four times a second, then either the X or Y output is overloaded and the corresponding noise calculation should be ignored. If the OVLD LED is on continuously, then the input signal is overloading the ac amplifier or time constant filters. In this case, both noise outputs will be wrong.

To obtain a value for the noise density, the noise reading should be divided by the square root of the ENBW. Thus, when the ENBW is 1 Hz, the noise output is the noise density, and when the ENBW is 10 Hz, the noise density is the noise output divided by √ 10. For example, if the input noise is measured to be 7 nV with the ENBW set to 1 Hz, the noise density is 7 nV/√ Hz. Switching the ENBW to 10 Hz results in a faster measurement and a reading of 22 nV on the output. The noise density is 22 nV/√ 10 Hz or 7 nV/√ Hz. At frequencies » 10 Hz, the noise density should be independent of the ENBW.

Power

This is the instrument'sPOWER switch. When the power is turned off, the front panel settings are retained so that the instrument will return to the same settings when the power is next turned on. The SR530 always powers up in the LOCAL mode.

The D/A outputs X5 and X6 are not retained during power off. X5 always becomes the RATIO output at power on and X6 is always reset to zero.

When the power is turned on, the CHANNEL 1 OUTPUT DIGITAL DISPLAY will show the SERIAL NUMBER of the instrument and the CHANNEL 2 OUTPUT DIGITAL DISPLAY will show the firmware VERSION. The REFERENCE DIGITIAL DISPLAY shows the model number of

the instrument. All displays return to normal after 3 seconds.

Local and Remote

When the instrument is programmed via the computer interface to be in the REMOTE state WITHOUT LOCK-OUT, the LOCAL key will return the instrument to LOCAL front panel control. If the instrument is in the REMOTE WITH LOCK- OUT state, no front panel key will return the status to LOCAL. In this case, a RETURN TO LOCAL command must be sent over the computer interface or the power must be turned off and back on.

Defaults

If the LOCAL key is held down when the POWER is turned on, the instrument settings will be set to the defaults shown below instead of the settings in effect when the power was turned off.

Parameter	Setting
BANDPASS	OUT
LINE	OUT
LINE X 2	OUT
SENSITIVITY	500 mV
DYN RES	LOW
DISPLAYS	X Y
EXPANDS	OFF
OFFSETS	OFF (value=0)
PRE TIME CONSTANT	100 mS
POST TIME CONSTANT 0.1 S
ENBW	1 Hz
REFERENCE MODE	f
TRIGGER MODE	SYMMETRIC
REFERENCE DISPLAY	FREQUENCY
PHASE SHIFT	0°

Whenever default values are used at power up, the red ERR LED will turn on for about 3 seconds. If the ERR LED is on when the instrument is powered on without the LOCAL key down, then the instrument is ignoring the retained settings. This can be due to a low battery.

SR530, Lock-In Amplifier specifications

The SRS Labs Lock-In Amplifier, model SR530, is a powerful tool designed for high-precision measurements in the realm of scientific research and industrial applications. This state-of-the-art instrument excels in extracting small signals from noisy environments, making it an invaluable asset for experiments in fields such as physics, engineering, and materials science.

One of the main features of the SR530 is its ability to perform synchronous detection, which is key to improving signal-to-noise ratios. By utilizing a reference signal, the device correlates the incoming signal with the reference to effectively filter out noise, allowing for the accurate measurement of weak signals that might otherwise be obscured. This process of phase-sensitive detection is fundamental to the operation of the Lock-In Amplifier.

The SR530 offers a wide frequency range, covering from 0.1 Hz to 100 kHz. This broad frequency response allows it to handle a diverse array of signals, making it suitable for various applications including optical detection, capacitance measurements, and in many cases, voltammetry. The device is also equipped with multiple inputs and outputs, facilitating the integration with other laboratory equipment and enabling complex experimental setups.

Precision is further enhanced with its adjustable time constant, which allows users to optimize the response time based on experimental needs. The user can choose time constants from 10 microseconds to 10 seconds, accommodating fast dynamic measurements as well as those requiring stability over longer durations.

Another remarkable characteristic of the SR530 is its digital processing capabilities. The device features a highly accurate digital voltage measurement system, minimizing drift and ensuring long-term stability. Additionally, the use of microprocessors enhances data handling and allows for features such as programmable settings, facilitating automated measurements.

Moreover, the SR530 includes a range of output options, including analog outputs, which can be used for direct signal processing, as well as digital interfaces for integration with computers. This ensures that users can not only capture high-fidelity data but also analyze and display it efficiently.

In conclusion, the SRS Labs SR530 Lock-In Amplifier stands out due to its sophisticated technology, versatile features, and robust performance. Its precision, flexibility, and ease of use make it an ideal choice for researchers and engineers looking to unlock the potential of weak signal measurement in complex environments.