Abstract: A photometer for use with a microscope having an object plane an image plane and an optical axis between said planes. The photometer includes an optical dividing means adapted to be disposed in the optical axis between the microscope object and image planes, and a reflective element having a reflecting surface. A pin hole occluder is adapted to be arranged on the opposite side of the optical dividing means to the reflective element. An optical imaging device provides an image of the pin hole occluder on the reflecting surface. A semi-reflective element is provided for reflecting light from the light source to the optical dividing means. A detector is arranged in an optical axis including the semi-reflective element, the pin hole occluder, the optical dividing means, the optical imaging device and reflective element.

Abstract: To allow rapid change between the conoscopic observation method and the orthoscopic observation method in a microscope, while showing a small overall size and permitting and optically correct position of the Bertrand lens and the associated diaphragm, an additional supplementary beam path can be selectively used in addition to the main beam path. The supplementary beam path includes the Bertrand lens and the iris diaphragm and extends away from the optical axis of the microscope objective in a lateral direction.

Abstract: In a microscope possessing an adjustable-inclination viewing tube and optical path system for erecting the image, an optical component forming part of the erecting system can be interchanged with another optical component. It is thus possible to select, at will, either a totally reflecting optical component, or an optical component which splits the beam into two, the latter optical component being usable for the purpose of attaching the microscope to a photographic device or similar accessory.

Abstract: In a microscope possessing an adjustable-inclination binocular unit and an optical path system for erecting the image, these two subsystems possess a common splitting prism, thus shortening the overall optical path in the microscope, so that the space required for the optical components remains small. This is of particular importance in cases involving microscope objectives which are corrected to infinity.

Abstract: A microscope has a support structure which comprises a base, an upright portion, a cross-head and an objective-turret assembly mounted on an underside of the cross-head. The cross-head is mounted on the upright portion and contains principal components for forming an image. The upright portion and the cross-head define a generally planar division therebetween, whereby a generally planar gas-tight seal can be provided between the upright portion and cross-head. This enables the upright portion and the base to be disposed in a gas-tight chamber while the cross-head is located outside the chamber.

Abstract: In a microscope with a motor-driven objective turret, an intermediate position is provided between each two adjacent primary turret positions. This intermediate position enables manual operations to be carried out on the objectives in the objective turret, in a convenient manner, before viewing. Automatic means are provided for switching off the motor in both the primary and the intermediate turret positions.

Abstract: Apparatus for the cryofixation of biological, medical or technical specimens having a high water content or fluid content by immersion in a cooling bath or on a metal mirror surface, comprises a container for coolant within which is disposed in a tank for specimen cooling medium. An injector is provided for holding a specimen and moving it along a delivery path. A member having a mirror surface is provided for mirror surface cryofixation, said member being adapted to be removably disposed at a position located in the injection path. A highly thermally conductive contact is provided between the tank and the member.

Abstract: Apparatus for the cryofixation of specimens, comprises a tank adapted to contain a cold gaseous medium having an upper boundary with an atmosphere external to the tank, and cooling means having an upper surface, said cooling means being disposed within the tank. The upper surface is movable between a lower level and an upper level which is below the upper boundary. The upper surface is maintained at the upper level for a period sufficient to permit the application of a specimen to the upper surface, and is then lowered to the lower level.

Abstract: A drafting apparatus, or macrophotography attachment, for a microscope of the inverted type, the apparatus being arranged to provide an erect and laterally non-reversed image of an object on a drawing-surface, and in the observation plane, or an erect and laterally non-reversed image of a drawing or object at the observation and film planes of a microscope.

Abstract: A marking image control system for a microscope arrangement in which the image of a marking on a mask is reflected into the optical path and combined with an object image of the microscope, the system forming an intermediate image of the marking in order to facilitate shifting of the image of the marking in a film plane or a viewing plane of the microscope.

Abstract: A device for immersing a specimen into a cryogenic cooling liquid comprising an injector for carrying a specimen, means for accelerating the injector to a predetermined velocity vertically into the liquid, and means for rotating the injector, before the vertical movement ends, or at the moment it ends, to promote heat transfer from the specimen. Various means for effecting rotation of the injector are described.

Abstract: Apparatus for cooling a biological or medical specimen comprises a cooling bath, an injection device for injecting a specimen into cooling liquid in the bath at a velocity of between 5 and 15 m/sec, and a sleeve. The sleeve is movable between a lower position in the bath and an upper position for limiting the effects of splashing as a specimen enters the bath. The injection device comprises a closure plate for co-operating with the sleeve to further limit the effects of splashing. The sleeve is operatively associated with the injection device in a manner such that movement of a specimen carrier of the device towards the bath to immerse a specimen is initiated when the sleeve is moved from the lower position to the upper position.

Abstract: In an optical deflecting device with an optical bridge and with two optical sub-units which can be rotated relative to the optical bridge, the optical sub-units are, in the datum position, aligned in a manner such that the optical entrance axis of the first optical sub-unit is substantially perpendicular to the optical exit axis of the second optical sub-unit and substantially parallel to the optical axis of the optical bridge. This arrangement enables a light beam to be deflected without altering the orientation of the image.

Abstract: A magnetic coupling comprises two parts of an optical instrument, for example, of a microscope, which are to be releasably coupled together. A locating surface is formed on one part, this surface comprising one or more areas defined by bodies composed of a magnetic material which are spaced apart at intervals, the other part comprising a locating surface comprising areas defined by bodies composed of a material which can be magnetized. In order to avoid mechanical shocks caused by a powerful magnetic attraction as the parts are coupled, the material which can be magnetized, and which is associated with one of the locating surfaces, is confined to one or more areas of this surface, the arrangement of these areas corresponding to that of the areas on the locating surface. Other parts of the locating surface are composed of a material which cannot be magnetized.

Abstract: A microtome, in particular an ultramicrotome, having a specimen carrier which can be moved relative to a knife. The specimen carrier includes a clamping aperture for holding a specimen. A light source is located inside the clamping aperture in the specimen carrier so that light is transmitted, from the rear of the clamping aperture, through a specimen block which is composed of a transparent material and through the specimen.

Abstract: A handling device for thin sections, in particular cryosections, which serves as a multifunctional device for transferring, pressing, and holding the thin sections. The device possesses a holder for at least one carrier grid, this holder comprising a base plate and a positively-guided cover plate which can be moved onto the base plate. In addition, means are provided for the purpose of clamping the cover plate against the base plate and hence against a thin section which is present on the carrier grid. A separate holder plate is preferably detachably located in the base plate, the carrier grid being permanently attached to this holder plate, which is matched, in shape and dimensions, to the specimen holder of an electron microscope.

Abstract: A cooling apparatus utilizing liquid nitrogen for cooling specimens to temperatures in the range from -100.degree. C. to -195.degree. C. in propane, halogenated hydrocarbons, isopentane, or other cooling media. Freezing of the cooling media is avoided by means of an arrangement wherein the liquid nitrogen cools the cooling-bath container and/or the liquifier only initially, but after the desired cooling-bath temperature has been reached, the liquid nitrogen level is lowered to below the height of a protective shell which results in further cooling being only indirect, via solid/solid contacts and via the gas phase. A constant cooling-bath temperature is ensured by means of a thermostatic temperature-control system while trouble-free standby operation is ensured by means of an automatic system for replenishing liquid nitrogen, and by a system for controlling the level of liquid nitrogen. Safe disposal of the cooling media which may be combustible and/or toxic is provided for.

Abstract: A microtome, especially an ultramicrotome, is disclosed in which a forward-feed system for the specimen arm and/or knife of the microtome comprises a stepping motor which is controlled by a pulse generator and which shifts the specimen arm, and the knife, relative to each other by an appropriate amount of forward feed in accordance with a forward-feed value which is set at one of a plurality of preselector switches. In order to facilitate quick switching over from one forward-feed amplitude to another, permitting the selection of forward-feed amplitudes which differ by an order of magnitude, for example, if semi-thin sections are to be produced during a run of ultra-thin sections, the forward-feed amplitudes set by the preselector switches can be switched, according to choice, to the pulse generator for the stepping motor by means of a changeover switch. This arrangement enables the operator to alter the forward-feed amplitude by one manual action without disturbing the ongoing operation.

Abstract: An infinity-corrected, semi-apochromatic microscope objective having an N.A. of 0.85 has five elements and provides a magnification of 50.times. when used with a telescope objective having an effective focal length (efl) of 183 mm.