Abstract: A capacitive position sensor has a periodic array of electrodes which form capacitors between pairs of the electrodes. The location of a dielectric inhomogeneity in the vicinity of the sensor is determined by comparison of the relative change in the capacitance of the capacitors. The comparison may be carried out using a capacitive Wheatstone Bridge arrangement. The sensor configuration has the advantage that it is independent of the absolute value of the dielectric constant of the environment in which the sensor is located.

Abstract: A Position Sensor comprises: one or more excitation windings; a signal generator adapted to apply excitation signals to the or each excitation winding; tag means displaceable relative to said excitation windings; one or more sensor windings electromagnetically coupled to said excitation windings such that in response to said excitation signals being applied to said excitation windings, there is generated sensed signal in the or each sensor winding; and a signal processor adapted to process said sensed signals to determine the position of said tag means in any location in the X, Y and Z planes essentially in accordance with phase values or in accordance with phase values and amplitude values.

Abstract: A process is described for denaturing native double-stranded nucleic acid material into its individual strands in an electrochemical cell. The process is an electrical treatment of the nucleic acid with a voltage applied to the nucleic acid material by an electrode. The process employs a promoter which is an inorganic multivalent cation such as a magnesium ion to speed denaturation. The process may be used in the detection of nucleic acid by hybridizing with a labelled probe or in the amplification of DNA by a polymerase chain reaction or ligase chain reaction.

Abstract: The invention provides a photocoagulator using an infrared laser diode source (70). A dichroic beam splitter (68) is used to combine the optical path of the laser system with the viewing system. Such an arrangement affords the clinician an uninterupted, uncolor view of the patient's eye during treatment, without any risk of damage to the clinician's eye. There is also provided an alignment system using a visible laser diode (80). The alignment system may include a number of mutually non parallel beams which pass through different portions of the pupil and provide information on aim, focus and vignetting.