Abstract: A watertight housing, preferably for photographic or cinematographical dees, which has a cover sealed against the penetration of water, which cover can be opened for access to at least one part that is important for putting a device arranged in the housing into operation. Viewed from the outside--behind the cover seal a moisture detector is provided. At least one evaluating device with a warning or signal device is connected to the moisture detector.

Abstract: To facilitate visual and/or electronic determination of the shape of a light-reflecting test object, a source of coherent light such as a laser produces an illuminating beam and a reference beam, the latter beam being combined in an optical system with reflections of the illuminating beam from the test object to form a holographic pattern on a receiving surface. The optical system includes a main objectives and two ancillary objectives, these ancillary objectives focusing the reflected rays of the illuminating beam and the rays of the reference beam upon two substantially coincident points so located on or near the axis of the main objective, in non-conjugate relationship with the receiving surface, as to train upon that surface a defocused composite beam producing a holographic pattern of contour lines. The substantially coincident points also lie in or near the plane of a real or virtual aperture stop, such as a pinhole diaphragm or its image.