Spectron Engineering - Factory Calibration

Factory Calibration

	Extremely high quality linear and rotary encoders are used at the factory to determine positional correction factors along all axis of movement within the DASH system. All positional movement and luminance calibrations are traceable to NIST standards. Factory calibration of the Transport module consists primarily of mechanical calibrations of each transport axis with its precision encoder. There is 64K resolution from the rotary encoder and ± .0001” resolution of the linear encoders. When plotted, the position output curve for even the best encoder is generally non-linear. This curve must be linearized to a very high degree in order to obtain the highest resolution possible from the system. Correction factors are defined for each encoder in each axis of movement to make the linearity of that encoder better than it was when received from the manufacturer. This provides great precision for Camera movement and confidence that the Camera is measuring the image at a point where the operator or software has directed. Factory calibration includes analyzing a grid and test data which is fed into a correction table which is stored and used by the system during operation. This corrects and refines the accuracy of each encoder. This calibration cannot be adjusted by the customer. Every Transport, and every Camera, stores its specific factory calibration information in EEPROMs. Camera factory calibration is of importance for both positional and luminance accuracy. The Camera detector has been tested at the factory to have zero defective pixels. It is tested for photometric linearity, and each pixel of the detector is calibrated and corrected for dark sensitivity errors. The focus transport mechanism of the Camera is calibrated similar to the Transport axes above. Correction factors are stored and utilized during 1420 DASH operations to maximize the accuracy of auto-focus measurements and for improvement of luminosity measurements both for no filter operation, and for ND filter operations.