A device has planar components forming part of a stack on a support frame, such as a substrate and upper layer, for example a fiber optic scintillator/fiber optic plate, bonded together by an adhesive layer of well-defined thickness. The device is made by providing a trench in a peripheral recess extending in a marginal portion of the support frame. Excess adhesive is applied to one of the planar components, which are then brought together such that the adhesive layer of well-defined thickness is formed between the two components and surplus adhesive is collected in the trench.