Laser scan bench for functional test of full
Laser scan bench for functional test of full hybrids. G. Casse
Purpose of the test Verification of the functionality of all channels in a module by firing a laser through each strip and reading out the response signal. The test doesn’t allow the evaluation of the S/N ratio, and no requirement of a calibrated laser intensity is made.
Width of the light spot Scan over a metal line Reconstructed light spot The FWHM declared by the manufacturer of the focuser is 6µm.
Hardware Hybrid placement jig, NA 60 read-out system (repeater board, control board, ADCs), video-camera, PC with I/O Ethernet card, GPIB communication, video-camera control, x-y DC motors table, DC motor controller, LV power supplies, HV power supply (for sensor biasing), Le. Croy oscilloscope, DG 535 digital delay pulse generator, 1060 nm laser driver and diode.
Motion system Controlled through Labview software. It uses the ESP 300 DC/stepper motion controller and two Newport DC motors 5 cm travel range, 0. 5 µm accuracy.
Laser and video-camera holder The laser focusing lens is kept in perpendicular axis to the detector plane and the height can be finely adjusted to the focal distance of 12 mm. Visible light can be shone through the optical system (optical fibre+focuser). This allows the focusing of the laser light on the detector plane. A video-camera allows the location of the light spot for aligning the system to the detector reference points.
Mounting jig The hybrid mounting jig is similar to the double sided bonding jig, to allow safe positioning of the hybrid to expose both R and Phi detectors to the laser light. Can provide vacuum holding of the module (not necessary due to the sufficiently precise positioning by the positioning pins) and water cooling.
Active head and mechanics The lens can be focused independently of the camera. The focus of the lens is tuned by shining visible light through the optic fibre onto a flat reflecting surface of the detector (metal pad). The range of the stages is not sufficient to cover the whole module, so the camera can be shifted between two different resting positions.
Cover for measurements with detector under bias.
Hybrid and repeater board
Other view of hybrid and electronics
Software (T. Huse) • Lab. VIEW programs to control the motion and the acquisition. • Main functionalities are the alignment of the reference system of the DC controller and the detector, the configuration of the chips, the positioning of the laser spot by every individual strip and read-out of the DAQ. • • The range of the stages moving the laser spot is not sufficient to cover the whole module, so after the first four ADC’s are read out, the camera must be shifted to position B. This also requires new measurements of the reference points. Data are saved in a specific directory tree specific for any individual hybrid (/data/DAQ/VELO_DATA/Hybrid. NN/Sensor/). Analysis are performed using a modified version of the VELO test-beam software and data are saved on the database. A functioning channel map is compared to the functioning channel map as determined by the sensor quality acceptance test on strips, and by the bonding map.
Results Customised analysis from Velo TB software (M. Tobin, K. Rinnert)
Results Customised analysis from Velo TB software (M. Tobin, K. Rinnert)
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