Fuss, Brian

LeCocq, Catherine

Ruland, Robert

UNT Digital Library

SLAC-WP-053Initial Calibration of a High Resolution Digital Camera for AcceleratorAlignmentWork supported by Department of Energy contract DE–AC02–76SF00515.Presented at 5th International Workshop On Accelerator Alignment (IWAA 97) ,13-17 Oct 1997, Argonne, IllinoisStanford Linear Accelerator Center, Stanford University, Stanford, CA 94309Initial Calibration of a High Resolution DigitalCamera for Accelerator AlignmentBrian Fuss, Catherine Le Cocq, Robert RulandStanford Linear Accelerator Center, Stanford, CA, USA.Equipment• Camera Body:   Nikon N90s• Camera Back:   Kodak DCS460m• CCD Size:   3060 pixels by 2036 pixels  27.6 mm by 18.4 mm• Nikkor Lens:   24 mm f2.8D• Storage:   PCMCIA Hard Disk Drive  170 MB, 340 MB• Flash:   Nikon SB-26Target Description• Shape: 9/16” diameter circle• Material: 3M Scotchlite High Gain SheetingTarget Layout• Initial: 100 targets on a  100 x 100 cm grid• Extended: 550 targets on a  275 x 235 cm gridwith 50 cm maximum depthAnalysis and ResultsSoftware: • Australis v1.0, University of Melbourne• Pattern Matching / Lego Bundle, SLACOverall results based on identical minimal constraints:	 	  	  	  			 	   	  	 ProcedureSix positions (as shown) were chosen for optimal geometriccoverage and adequate redundancy. They were “permanently”marked so that  the geometry of the survey could be keptconstant. Testing the impact of the geometry is easier thanisolating camera-specific factors.Testing1) Repeatability• short term (< 1 hour)• long term (> 1 week)2) Handling Effects• camera manipulation• lens removal3) Orientation• 0º, 90º, 180º, 270º and 360º rollConclusionsThese tests have shown that fast and accurate alignment of accelerator components is possible using the non-metric KodakDCS 460m digital camera shortly after being calibrated. The two software packages provided comparable solutions. Shortterm repeatability was achieved. The effect of orientation changes, camera jarring and the lack of long term repeatability, allpoint toward an internal displacement of the CCD chip.Examination of the CCD housing and careful manipulation of the chip itself indicated that indeed it moves. Being a non-metric camera that would normally sustain jarring, the spring mechanism is reasonable for non-photogrammetric use. Twoclamps were designed to hold the chip stable. Further testing of this new chip configuration is planned.Calibration Parameter Value RepeatabilityFocal Length f 24.330 mm 0.030 mmxp -0.200 mm 0.050 mmPrincipal Point Offset yp -0.100 mm 0.050 mmK1 1.65 x 10-4 5 x 10-6K2 -2.9 x 10-7 5 x 10-8Radial SymmetricDistortionK3     -2 x 10-10 10-10P1  3.5 x 10-6 N/ADecentering Distortion P2 -1.4 x 10-5 N/AB1 -1.5 x 10-3 5 x 10-4Correction for Affinityand Non-Orthogonality B2  0.5 x 10-3 5 x 10-4

Initial Calibration of a High Resolution Digital Camera for Accelerator Alignment

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Initial Calibration of a High Resolution Digital Camera for Accelerator Alignment

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