Abstract: An objective has a front group, a focus group displaceable along the optical axis and a follow-on lens group having a diaphragm. The front group is arranged at the objective end. The lens group having the diaphragm includes at least two composite lenses and/or two positive lenses and/or the back focus can be adjusted. An objective series is presented wherein all objectives of the series have a uniform appearance and/or the diaphragm is arranged in all objectives proceeding from the image plane at the same location.

Abstract: The present invention relates to an image-forming objective which is capable of forming sharp images of objects at at least two different distances from the objective, there being arranged at one focal plane of the objective a corrective element divided into at least two fields in which the refractive power differs between them.

Abstract: This invention relates to a device for use when evaluating optical signals by means of a chopper (2, 2'), i.e. a rotating shutter, and a photodetector (6, 6') for detecting the signal transmitted through the chopper (2, 2'). In order to improve the evaluation of the incident signal the opaque part (3, 3') of the chopper is provided with a reflective surface (7) to utilize also the optical signal falling on the opaque part (3, 3'). An additional photodetector (9, 9') has been arranged for detecting this reflected optical signal. In order to reduce the energy losses and in this way increase the amplification of the optical signal the device also comprises an optical element in the form of a glass prism (10, 10') in which one and the same surface is utilized both for transmitting and reflecting the optical signal.

Abstract: The invention relates to a binocular night telescope of the type which comprises a large aperture objective (1), a light amplifier tube (2) for amplifying the image projected by said large aperture objective and a viewing microscope which comprises telescope objectives (9, 10) and oculars (11, 12) as well as a collimating objective (6) for focusing the amplified image at infinity for an observer. The viewing microscope also comprises prisms or mirrors for erecting the image vertically as well as in side. At least a part of the prisms (7, 8) for erecting the image in side are axially displaced so that they are located at the side of, above or below the light amplifier tube (2) depending on the orientation of the microscope. This means that the entire instrument is shorter and the center of gravity is moved forwards.