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Proceedings Paper

Six-channel polychromator design and implementation for the UPC elastic/Raman lidar
Author(s): Dhiraj Kumar; Francesc Rocadenbosch; Michaël Sicard; Adolfo Comeron; Constantino Muñoz; Diego Lange; Sergio Tomás; Eduard Gregorio
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Paper Abstract

A 6-channel dichroic-based polychromator is presented as the spectrally selective unit for the U.P.C. elastic/Raman lidar. Light emission is made at 355-nm (ultraviolet, UV), 532-nm (visible, VIS) and 1064-nm (near infrared, NIR) wavelengths. In reception, the polychromator is the spectral separation unit that separates the laser backscattered composite return into 3 elastic (355, 532, 1064-nm wavelengths) and 3 Raman channels (386.7, 607.4 and 407.5-nm (water-vapor) wavelengths). The polychromator houses photo-multiplier tubes (PMT) for all the channels except for the NIR one, which is avalanche photodiode (APD) based. The optomechanical design uses 1-inch optics and Eurorack standards. The APD-based receiver uses a XY-axis translation/elevation micro-positioning stage due to its comparatively small active area and motorised neutral density filters are used in all PMT-based channels to avoid detector saturation. The design has been specially optimized to provide homogeneous spatial light distribution onto the photodetectors and good mechanical repeatability. All channels are acquired in mixed analog and photon-counting mode using Licel® transient recorders, which are controlled by means of a user friendly LabVIEWTM interface. The paper focuses on the main polychromator optical design parameters, that is, light collimation trade-offs, end-to-end transmissivity, net channel responsivity, light distribution and spot size onto the photodetectors. The polychromator along with the rest of the U.P.C. lidar system has successfully been tested during a recent lidar system intercomparison campaign carried out in Madrid (Spain) during Oct. 2010.

Paper Details

Date Published: 30 September 2011
PDF: 10 pages
Proc. SPIE 8182, Lidar Technologies, Techniques, and Measurements for Atmospheric Remote Sensing VII, 81820W (30 September 2011); doi: 10.1117/12.896305
Show Author Affiliations
Dhiraj Kumar, Univ. Politècnica de Catalunya (Spain)
Francesc Rocadenbosch, Univ. Politècnica de Catalunya (Spain)
Michaël Sicard, Univ. Politècnica de Catalunya (Spain)
Adolfo Comeron, Univ. Politècnica de Catalunya (Spain)
Constantino Muñoz, Univ. Politècnica de Catalunya (Spain)
Diego Lange, Univ. Politècnica de Catalunya (Spain)
Sergio Tomás, Univ. Politècnica de Catalunya (Spain)
Eduard Gregorio, Univ. de Lleida (Spain)


Published in SPIE Proceedings Vol. 8182:
Lidar Technologies, Techniques, and Measurements for Atmospheric Remote Sensing VII
Upendra N. Singh; Gelsomina Pappalardo, Editor(s)

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