Abstract: A method and apparatus for a fault tolerant recording system using a laser diode array is disclosed. The laser diode array comprises individually addressable diodes which are used to record data on parallel tracks of a recording surface. Narrowing the separation between the parallel recording tracks without modifying the diode spacing within the array may be accomplished by precise movement of the diode array with respect to the recording surface, so as to generate an interleaved recording pattern. Fault tolerance is added by creating a redundancy (integrated into the interleaving mechanism) wherein each track on the recording surface is assigned a primary diode and a secondary diode, only one of which is active at a particular time. If a failure occurs in the primary diode assigned to a particular track, then the secondary diode is activated, and the recording of data on the particular track remains unaffected.

Abstract: A method for exposing photo-sensitive printing plates comprises applying a patterned coating to the printing plate to form a mask. The coating may be sprayed onto the printing plate and patterned by laser ablation. The method avoids the need to stock printing plates with integral masking layers. In preferred implementations the printing plate is exposed to actinic radiation without dismounting it from the apparatus in which the coating is applied. This minimizes the likelihood that the coating could be damaged in handling. The coating may be a thin sprayed on layer of carbon in a suitable binder.

Abstract: A method for compensating for image distortion imparted on a flexographic printing plate is disclosed. The compensation scheme reduces the distortion effect caused by stretching of the image when the printing plate is wrapped around the cylindrical drum of a printing press. The compensation scheme predicts the localized distortion on different parts of the image caused by variations in the undercut depth and density of the image features on the plate. By so doing, the scaling factor is varied in accordance with the predicted localized distortion in the different parts of the image, so as to minimize the distortion effect over the entire printing plate.

Abstract: A plate for flexographic, or `raised image`, printing consists of a backing layer, an intermediate layer and a top layer. The backing comprises a thin metallic sheet or a thin polyester sheet for dimensional stability. The intermediate layer is a closed-cell elastomer foam. The top layer is a thin layer of solid elastomer. The intermediate layer absorbs strongly at an operating wavelength where the backing is either essentially transparent or highly reflective. When the plate is cut with a laser operating at the operating wavelength then the cutting action is self-limiting. As soon as the backing is exposed to the laser beam then the beam is either transmitted through the backing or reflected from the backing. In either case damage to the backing is avoided. Most of the thickness of the plate is in the intermediate layer which has a low density. Thus it takes much less energy to cut a plate according to the invention than is required to laser cut conventional flexographic printing plates.

Abstract: A method and apparatus for an improved autofocus in an optical system is presented. The improved autofocus system uses distinct optics from those of the primary optical system. Although optically distinct, physically, the autofocus optics are mechanically linked to the optical output stage of the primary optical system. The optical separation of the autofocus optics from those of the primary optical system overcomes the trade-offs associated with trying to combine the primary optical function and focus in the same beam. In particular, the autofocus beam is not blinded by a more powerful write beam. The physical integration of the autofocusing optics with the optical output stage of the primary optical system overcomes the difficulties associated with using external distance sensors. In particular, the autofocusing system is not susceptible to steady state error because the autofocus sensor is a true null detector.

Abstract: Low contrast optics, including low contrast linear light valves, can be used to create high resolution patterns by using thermoresist instead of photoresist and by using multiple exposures of the same area, preferably exposing different features of the pattern in each exposure. When using thermoresist, the stray light from imaging the individual features does not add up, as the stray heat it creates will dissipate between exposures. The method is particularly useful for imaging thermoresists using UV light for manufacturing of integrated circuits.

Abstract: A square laser recording spot, having an energy profile with a very sharp transition between the writing and non-writing area in both dimensions, is created by a shaping the laser energy into a line narrower than the desired spot size and scanning this line to create a square spot. The sharp transition resists changes in the writing process which could vary the size of the mark created by the spot. The square shape of the mark avoids dot gain and eliminates the need for dot gain calibration.

Abstract: A method of high resolution imaging for integrated circuits employs two masks and a laser source to impart an image onto a thermoresist coated image receiving surface. A primary mask carries a principal image to be recorded and a secondary mask contains an array of lenslets. The lenslet array concentrates light from a pulsed laser source onto a plurality of exposure points on the primary mask and the image features contained within that plurality of exposure points are imagewise reproduced in a corresponding plurality of exposure points on the image receiving surface. The lenslets in the lenslet array are dimensioned and positioned such that the plurality of exposure points formed on the image receiving surface have sufficient separation to avoid interaction. Relative motion ("scanning") between the primary and secondary mask creates raster lines on the primary mask to be exposed onto corresponding raster lines on the image receiving surface.

Abstract: A method and apparatus for high resolution imaging of integrated circuits and flat panel displays uses a pulsed laser source, a thermoresist coated image receiving surface and a pair of masks. A primary mask carries the principal image and a secondary mask containing an array of lenslets which concentrate light from the source onto a subset of the features of the primary mask. The secondary mask lenslets are dimensioned so as to illuminate a subset of the features with a known pitch and form an image corresponding to the subset on the thermoresist. After creating a subset image, the secondary mask is moved so as to expose another subset of the features and form another subset image. In this manner, the entire principal image is reconstructed on the thermoresist from subset images. The secondary mask is moved on two axes by a plurality of piezo-electric actuators.

Abstract: A method for directly imprinting a plate in flexographic, or `raised image`, printing uses a plate having an imprinting layer of a foam material. When an area of the imprinting layer is heated with a laser operating at an operating wavelength then a quantity of the foam material in the imprinting layer melts and re-solidifies. The re-solidified material has significantly less volume than the foam material had before it was melted. This leaves a recessed area in the printing surface. The method requires less energy than would be necessary to remove material from the printing surface by laser ablation. Furthermore, fewer noxious gases are produced by the method than are produced in ablative methods.

Abstract: A method for creating a flexographic printing plate includes creating a mask which has opaque and non-opaque regions. The non-opaque regions have variable optical densities. Areas of the mask corresponding to portions of the plate which will require higher exposures have lower optical densities. Areas of the mask corresponding to portions of the plate which will require lower exposures have higher optical densities. A flexographic photo-polymer printing plate is exposed through the mask. The varying optical density of the mask allows all portions of the printing plate to be exposed with a single exposure. The mask may include a thermal film which may be integral with the printing plate.