THE LUPM RAMAN LIDAR
Designed for the CTA South Observatory

The LUPM Raman Lidar Concept

Fast Pointing & Fast Acquiring

Based on a reconditioned CLUE experiment container, the LUPM Raman Lidar is designed with CTA in mind. Aimed to take data only within a lifespan of a couple of minutes, it incorporates big optics and high efficiency electronics to achieve this goal.

The Telescope, Laser and Optics

Big Optical surfaces, High collection efficiency

The telescope is built around an 1.8m diameter UV mirror. Mounted in an alt-azimuth mount it is equiped with fast repositioning motors.The Unpark/Park procedure takes 45 seconds

A mils specs QUANTEL laser CFR-400 provides a 355nm/532nm beam light trace, guided through 2" UV optical mirrors through a coaxial configuration. A motorized piezomotor system assured the online optical alignement.

Backscattered light is collected at the focal point through a Lumatec liquid fiber optics that delivers the signals to the polychromator assebly.

The Raman Polychromator and Acquisition Chain

Raymetrics Custom Design & Licel DAQ

We have worked with the Raymetrics Co to bult a custom polychromator adapted to the telescope characteristics and Acquisition constraints. It is a four channel unit, two elastic channels and two Raman ones. It accomodated big Optics and mirrors that were also custom built to our needs.

The Custom Designed Photomultiplier Operating Mode

Keep parasite light to a minimum

To deal with the stray light coming from the laser pulsing beam and the constraint of having maximum of 500mV on the inputs of the Licel modules, we have developped a gated trigger system for the operation of the photomultipliers. During the fist fw nsec the photomultipliers are blinded" so saturation of their input system is prohibited.