A buffer and return device for a slide rail in a drawer attached to an outer rail of the drawer and includes a base, a buffer plunger and an elastic element. In order to also be able to carry out a correction for curvature, at least one incident light beam, which is essentially parallel to the first or second light beam, is oriented toward the front surface of the sample, and at least one detector is provided for detecting a light beam of the parallel light beam reflected by the sample and for determining the position thereof. Erlotinib hydrochloride can be used as medicament for the treatment of hyperproliferative disorders, such as cancers, in humans. If this is done, the change of gain in EDF with respect to oscillation wavelength can be made satisfactorily small and the NF can be made satisfactorily small.