th The 4 ESO CCO Workshop, Optical Detectors for Astronomy, was held during September 13-16, 1999 at its usual location, the headquarters of the European Southern Observatory in Garching, Germany. We prefer to remember this workshop as a "meeting of friends", who came to Garching to visit ESO and to present their work, rather than a formal meeting. Based on our experience with the 1996 ESO CCO workshop, we deliberately put emphasis on creating an environment that encouraged the participants to stay together and informally exchange ideas. These informal events began with a tour of the BWM auto factory and continued with a reception at "SchloB Beletic", the conference dinner at a real SchloB of the Bavarian International School (where the participants enjoyed basket, baseball, table soccer, rock climbing and eventually dancing) and concluded with a tour of the Paulaner Brewery and dinner at the Seehaus in the Englisher Garten. The lunch "Biergarten", adjacent to the poster session area, was a daily meeting point. The result was a good mixture of excellent presentations and posters, collected in these Proceedings, and many occasions for people to get in touch and to have fun together, as witnessed by the selection of workshop pictures that we randomly placed between papers. This book contains a special contribution.

The invention and early history of the CCD.- From photographic plates to CCDs.- Detectors at the Nordic Optical Telescope.- Mission accomplished - ESO's optical detector systems come of age.- Charge coupled devices at ESO - Performances and results.- CCD systems for PMAS - A new optical integral field spectrophotometer for the Calar Alto Observatory 3.5m telescope.- GTC - Present status and future plans.- CCDs for the Rosetta science imaging system OSIRIS.- CCD plans for the Subaru telescope.- CTIO detectors: present status and future plans.- COROT: high photometry stability with CCDs.- CFH12K: optimising 12 MIT/LL CCID-20 CCDs for a direct imaging application.- MegaCam: the next generation wide-field camera for CFHT.- The current state of the art in large CCD mosaic cameras, and a new strategy for wide field, high resolution optical imaging.- CCD mosaicing technique for Suprime-Cam (SUbaru PRIME focus CAMera).- BUSCA: a simultaneous 4 colour camera with 4K×4K CCDs.- Focal plane array design for the GAIA space mission.- CFH12K: 12Kx8K CCD mosaic camera for the CFHT prime focus.- The life of Riley "New age CCD technology".- CCD imager technology development at Lincoln Laboratory.- Point-spread function in depleted and partially depleted CCDs.- High speed pn-CCDs as wave front sensors in adaptive optics systems.- Latest EEV CCD developments, and technologies for scientific CCDs.- A 2Kx2K high resistivity CCD.- Backside illuminated pixel detectors.- Development of a back-illuminated 4Kx4K CCD with low-noise outputs.- Optimising CCDs for spectrographs.- A new CCD designed for curvature wavefront sensing.- Phase resolved high speed photometry and spectroscopy of pulsars.- The removal of periodic read-out patterns from science frames.- Centering accuracy with CCDs.-The TAROT CCD camera.- Cloud monitoring with CCDs.- Using KAF-4201 CCDs for astronomy.- A new machine for planarity measurement of CCDs and mosaics of CCDs..- Design concepts of high resolution solar imagers based on split-transfer CCDs.- CCD optimisation methods at LICK Observatory.- TNG new generation CCD controller.- SciMeasure wavefront sensor cameras and their application in the Palomar adaptive optics system.- The 72-Channel S.A.O. Megacam: design to PC boards.- The implementation of the San Diego State University Gen II CCD controller (SDSU II) at the Isaac Newton Group of Telescopes (ING).