Abstract: An apparatus and method for imaging a sample, the apparatus including a source for irradiating a sample with a beam of substantially continuous electromagnetic radiation having a frequency in the range 25 GHz to 100 THz; means for subdividing an area of the sample which is to be imaged into a two dimensional array of pixels; means for detecting radiation from each pixel wherein the detector is configured to detect a phase dependent quantity of the detected radiation which is measured relative to the radiation which irradiates the sample.

Abstract: A system for investigating a sample, the system including a detector having non-linear current voltage characteristics and being configured to mix two radiation signals having frequencies in the range from 25 GHz to 100 THz, one of the signals being a local oscillator signal and the other signal being a sample signal carrying information about the sample being investigated, the system further having a quantum cascade laser for providing at least the local oscillator signal.

Abstract: An apparatus for investigating a sample, the apparatus comprising an emitter (1) for irradiating the sample (27) with a beam of emitted electromagnetic radiation; and a detector (49) for detecting the radiation reflected from the sample, wherein there is an optically non-linear member (15) which functions as both an active part of the emitter and an active part of the detector, said emitter and detector using the same part of the optically non-linear member (15). The electromagnetic radiation is primarily intended to be in the terahertz (THz) frequency range.

Abstract: A system for investigating a sample, the system comprising a detector having non-linear current voltage characteristics and being configured to mix two radiation signals having frequencies in the range from 25 GHz to 100 THz, one of the signals being a local oscillator signal and the other signal being a sample signal carrying information about the sample being investigated, the system further comprising a quantum cascade laser for providing at least the local oscillator signal.

Abstract: A probe for examining a sample (5), the probe comprising an emitter (1) for emitting radiation, a detector (1) for detecting radiation and a dielectric member (3) configured to direct radiation from the emitter (1) to the sample (5) and to direct radiation reflected by the sample (5) to the detector (1), wherein in use, the dielectric member (3) occupies at least half of the radiation path length from the emitter (1) to the sample (5) to the detector (1).

Abstract: An apparatus for investigating a sample comprising a source of a beam of radiation, a detector for detecting a beam of radiation reflected by or transmitted through a sample to be imaged, an optical subsystem for manipulating the beam between the source and detector and means for translating the optical subsystem along a first translation axis relative to the source and detector to scan the beam across the sample, wherein the source and the detector are on opposite sides of the subsystem and the beam from the source and the beam reflected or transmitted each enter and exit the subsystem in a direction parallel to the first direction of translation. The apparatus is also suitable for maintaining the relative phase of two beams of radiation, during translation of an optical subsystem.

Abstract: An apparatus and method for imaging a sample, the apparatus comprising: a source for irradiating a sample with a beam of substantially continuous electromagnetic radiation having a frequency in the range 25 GHz to 100 THz; means for subdividing an area of the sample which is to be imaged into a two dimensional array of pixels; means for detecting radiation from each pixel wherein the detector is configured to detect a phase dependent quantity of the detected radiation which is measured relative to the radiation which irradiates the sample.

Abstract: An apparatus for investigating a sample, the apparatus comprising an emitter (1) for irradiating the sample (27) with a beam of emitted electromagnetic radiation; and a detector (49) for detecting the radiation reflected from the sample, wherein there is an optically non-linear member (15) which functions as both an active part of the emitter and an active part of the detector, said emitter and detector using the same part of the optically non-linear member (15). The electromagnetic radiation is primarily intended to be in the terahertz (THz) frequency range.

Abstract: An apparatus and method for investigating a sample, the apparatus comprising: means (61) for irradiating the sample (21) with a first beam of electromagnetic radiation configured to excite an optically non-linear process within the sample; means (61) for irradiating the sample with a second beam of electromagnetic radiation; and a detector (41) for detecting a change the second beam after it has been reflected from or transmitted through the sample. If the optically non-linear process is a second order process, the detector could be used to detect a change in the polarisation of the second beam. Apparatus and method find application of samples with terahertz (THZ) radiation locally generated and detected within the sample.

Abstract: A range of technique for investigating a sample such as obtaining images and/or spectral information are described. The techniques include a method for deriving structural information about a sample as a continuous function of the depth below the surface of the sample, a method for evaluating a part of the structure of a sample located between two interfaces within the sample, and a contrast enhancing method and apparatus which has a quick image acquisition time.

Abstract: A rotary valve assembly comprising a housing defining a bore and a valve member mounted for rotation therewithin. The housing defines an opening and the valve member has a port which comes into and out of registration as the member rotates. Lubricant is supplied between the two members and sealing means are provided around the opening in the housing to effect a seal with the valve member. The sealing means includes a sealing element disposed in at least one groove formed in the housing parallel to the axis of the bore, the element being urged into contact with the valve member.

Abstract: This invention relates to an improved continuous calcining apparatus for consistently and controllably producing from calcinable reactive solid compounds of uranium, such as ammonium diuranate, uranium dioxide (UO.sub.2) having an oxygen to uranium ratio of less than 2.2. The apparatus comprises means at the outlet end of a calciner kiln for receiving hot UO.sub.2, means for cooling the UO.sub.2 to a temperature of below 100.degree. C and conveying the cooled UO.sub.2 to storage or to subsequent UO.sub.2 processing apparatus where it finally comes into contact with air, the means for receiving, cooling and conveying being sealed to the outlet end of the calciner and being maintained full of UO.sub.2 and so operable as to exclude atmospheric oxygen from coming into contact with any UO.sub.2 which is at elevated temperatures where it would readily oxidize, without the use of extra hydrogen gas in said means.

Abstract: A valve for controlling the flow of gases, or fluids, which comprises a stationary valve housing having an opening in its face and a movable valve member having a face rotatable, or slidable, over the face of the valve housing and having a port or ports in the face which comes into and out of communication with the opening, there being means to supply liquid lubricant between the valve and housing faces and means capable of reducing the lubricant film thickness between the valve and housing faces in the region of the valve port and its opening into the combustion chamber to from 40 to 50.mu. inches.

Abstract: An internal combustion engine having a rotary valve for controlling the inlet of fuel and exhaust of combustion products from the engine arranged to supply copious lubrication to the valve face and to remove excess lubricant before the valve registers with the combustion chamber inlet to leave a lubricant film of thickness not exceeding 40 to 50.mu. inches, the lubricant flowing through a series of concentric sealing rings, or a spiral groove in the valve housing or the valve surrounding the area of register of the valve opening into the combustion chamber.

Abstract: In a rotary valve controlling the inlet of fuel to, and exhaust of combustion products from, a combustion chamber, an improved seal is achieved by providing rigid upstanding lips in the valve housing about the opening of the housing into the combustion chamber, the lips sloping away from the combustion chamber opening and the housing being split diametrically for movement about a hinge pin to provide flexibility to the system and prevent clamping on the valve.

Abstract: Apparatus for removing the excess lubricant from a rotatably mounted cylindrical valve member for internal combustion engines, pumps and compressors includes a rigid scraper blade mounted within a housing and resiliently biased toward the surface of the cylindrical valve member. The lubricant is supplied copiously to the surface of the cylindrical member at one position and is removed as the cylindrical member rotates at a second position by the rigid blade which has an extremely small degree of flexibility so that it is deformed by an amount not greater than 1/3000 of the diameter of the cylindrical valve member when the blade and a recess in the cylindrical valve member are in register.