Abstract: Method to arrange and adjust a laser that is stable with respect to external and internal influences, and which comprises at least three optical components consisting of a laser element (1), which can generate optical radiation within a wavelength band .lambda..sub.1 -.lambda..sub.2, an optical collimator (2) that inside the laser collimates radiation emitted from the laser element, and a plane reflection grating (3) with parallel grating grooves, arranged such that the latter together with a flat reflection surface, which can be one end surface of the laser element, forms a resonator, that selects the radiation wavelength emitted by the laser. At least one optical component, which for instance can be (1), (2) or (3) is fixedly mounted in a holder, that for the purpose of adjusting the laser to a lasing condition can be turned about an axis, that is fixed in the device, such that the angle .PHI.