Abstract: A two-part coaxial needle for a pipetting device, in particular for use in microscopy of cell probes, makes it possible both to inject a liquid into a pipetting container and to remove by suction a liquid from the pipetting container. Both the drive for lowering the coaxial needle into the pipetting container, and injection and removal by suction of the liquid take place pneumatically by way of only one pressure source. The design of the coaxial needle and of the drive systems makes possible fast and reliable pipetting with high metering accuracy and a particularly compact pipetting unit which without mutual interference can be used with a multitude of widely-used microscope types.

Abstract: An immersion objective for microscopic investigation of a specimen is provided wherein an outer lens is disposed in an objective body. A delivery device including a cap that is disposed over the objective body so as to form a space adapted to receive an immersion liquid is also provided. The cap is open in a region of the outer lens so as to form a gap with the outer lens. The cap includes at least one connector configured to provide a continuous supply of the immersion liquid to the space so that the immersion liquid emerges through the gap to a region between the outer lens and at least one of the specimen and a specimen slide.

Abstract: A two-part coaxial needle for a pipetting device, in particular for use in microscopy of cell probes, makes it possible both to inject a liquid into a pipetting container and to remove by suction a liquid from the pipetting container. Both the drive for lowering the coaxial needle into the pipetting container, and injection and removal by suction of the liquid take place pneumatically by way of only one pressure source. The design of the coaxial needle and of the drive systems makes possible fast and reliable pipetting with high metering accuracy and a particularly compact pipetting unit which without mutual interference can be used with a multitude of widely-used microscope types.

Abstract: An immersion objective for microscopic investigation of a specimen is provided wherein an outer lens is disposed in an objective body. A delivery device including a cap that is disposed over the objective body so as to form a space adapted to receive an immersion liquid is also provided. The cap is open in a region of the outer lens so as to form a gap with the outer lens. The cap includes at least one connector configured to provide a continuous supply of the immersion liquid to the space so that the immersion liquid emerges through the gap to a region between the outer lens and at least one of the specimen and a specimen slide.

Abstract: A sample holder for handling samples to be viewed under a microscope, and which comprises a base frame 1 provided with a lower surface 2, an upper surface 3, and at least one receiving area 4 for at least one sample. In order to facilitate examination of a large number of samples, the sample holder is provided with a coupling area 5 on its upper surface for receiving at least one other functional element, such as a sample fixing element, a heating or cooling plate, or a cover.

Abstract: The moment of beginning of fracture in breaking strength tests of ferromatic samples (7) is detected by the spreading of a magnetic field out of the incipient crack in the magnetized sample by means of a magnetic probe (23). Until the beginning of the crack, the magnetic field runs through the magnetized sample. The voltage induced in the magnetic probe at the moment the crack starts is used to stop a time measuring counter which was reset and turned on at the beginning of the stressing of the sample.

Abstract: A method of determining the impact fracture toughness K.sub.id of construction materials, for example structural steels or plastic materials, without the need of performing a load measurement at the striking hammer is provided. The elastic response of the specimen to the impact process, i.e. the dynamic stress intensity factor versus time curve, K.sub.I.sup.dyn (t), is determined in pre-experiments. The shadow optical method of caustics in reflection with an appropriate high strength steel is utilized for establishing this impact response curve. The dynamic fracture toughness for a given constructional material is then determined by performing an impact experiment and measuring the time to fracture t.sub.f. K.sub.Id is obtained from the measured t.sub.f -value and the pre-established impact response curve which corresponds to the experimental test conditions. The presented measuring procedure is used for determining the dynamic fracture toughness of two different steels at different test temperatures.