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Time-dependent attenuator for dynamic range reduction of lidar signals
Applied Optics
|May 20, 1997
Summary
A novel variable attenuator for lidar systems electronically controls signal dynamic range, reducing it by over 100 times. This innovation enhances data acquisition for atmospheric measurements across extended vertical ranges.
Area of Science:
- Atmospheric Optics
- Laser Remote Sensing
- Optical Engineering
Background:
- Lidar systems require management of wide dynamic ranges in signal intensity.
- Close-range targets produce strong signals, while distant targets yield weak signals.
- Existing methods may not offer sufficient flexibility for dynamic range reduction.
Purpose of the Study:
- To introduce and characterize a time-dependent variable attenuator for lidar receivers.
- To reduce the signal dynamic range for improved data acquisition.
- To enhance the operational flexibility of lidar systems for varied measurement scenarios.
Main Methods:
- Incorporation of a Pockels cell between crossed polarizers into the lidar receiving optic.
- Electronic control of the Pockels cell's transmission properties.
- Investigation of reproducibility and the impact of rise times on attenuation.
- Assessment of systematic errors in differential absorption lidar (DIAL) measurements.
Main Results:
- Signal dynamic range reduced by over a factor of 100.
- High reproducibility of attenuation with statistical error below 10(-3).
- Negligible systematic errors in DIAL for relative wavelength differences < 0.1%, with correction methods outlined.
- Demonstrated ability to adapt measurement range and extend coverage to lower altitudes.
Conclusions:
- The variable attenuator effectively reduces lidar signal dynamic range.
- The system offers high reproducibility and minimal systematic errors for DIAL.
- It enables extended height coverage (0.2-10 km) with a single data-acquisition channel, improving lidar system versatility.
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