Abstract: A method is described for optimizing recording conditions for writing information on an optical record carrier. The information is written on the record carrier in the form of optically detectable marks, each mark being written by a pulse series of radiation. A series of test patterns is written on the record carrier (1) for the optimization. A jitter detector (11) measures both the leading-edge and trailing-edge jitter of the read signal. The leading-edge jitter is used to optimize the value of a parameter influencing only the leading part of a pulse series. The trailing-edge jitter is used to optimize a parameter influencing only the trailing part of the pulse series.

Abstract: The illumination system (1) has a substrate (2) and an active layer (3) comprising an electroluminescent material, in which the active layer (3) is present between a first, optically transparent electrode layer (5) and a second electrode layer (7). The illumination system (1) is characterized in that a light-scattering layer (28) comprising a medium having light-scattering properties is present in a forward direction (29) with respect to the active layer (3), in which the non-scattered fraction of a (collimated) light beam, when passed through the light-scattering layer (8) in the forward direction (29), is in the range between 0.05 and 0.8, preferably in the range between 0.1 and 0.5. The light-scattering properties of the medium are preferably stronger as the light is more obliquely incident, as is achieved by using birefringent particles and/or media. A very suitable light-scattering layer (28) is a (half) monolayer of TiO.sub.

Abstract: An array of semiconductor diode lasers (11, 12) is a very suitable radiation source for various applications such as optical read and write systems and laser printers. Such an array includes a semiconductor body (10) with a substrate (1) and a layer structure provided thereon in which at least two lasers (11, 12) are formed which are mutually separated by a groove (20). In the known array, the groove (20) reaches down into the substrate (1), so that the lasers (11, 12) are electrically separated from one another. According to the invention, the array of lasers (11, 12) is provided with a groove (20) with a major portion (d) of its depth (D) which is situated within the substrate (1). As a result of this, the lasers (11, 12) of the array show a surprisingly low crosstalk. Preferably, the portion (d) of the groove (20) situated in the substrate (1) is at least 3 .mu.m deep. The best results are obtained with depths (d) of approximately 10 up to at most 40 .mu.m.

Abstract: An apparatus and method for recording an information signal on a record carrier by means of a radiation beam which produces optically detectable marks in parallel track portions thereon having a substantially constant track pitch (q). The write intensity of the radiation beam is adjusted to an optimum level which results in a width (p) of the optical marks which corresponds to the track pitch (q). The optimum intensity level is determined by recording different test signals in adjoining track portions at various write intensities of the radiation beam, reading-out the recorded test signals, and detecting therefrom the write intensity at which signal components of one test signal no longer occur in another recorded test signal. Recording at the optimum write intensity results in a minimum block error rate (BLER) upon read-out of the recorded information signal.