An array of bottom-emitting VCSELs, with its substrate still intact, is tested by means of a probe that includes an optoelectronic array, which is aligned and coupled to the top surface of the VCSEL array. The draft is then executed by the debt collector as authorized signatory for the payor, and deposited into the payee’s account to complete payment. This decoupling is accomplished by having the height-adjusting arrangement form a system which connects the track-laying units or wheels to the chassis not rigidly but in such a way that they are able to move. Cooling air is metered through the metering holes, then impinged against the diffusion channel and then diffused into the ducts and discharged as film cooling air over the endwall surface.