Abstract: An apparatus for determining fractional amounts of each phase of a multiple phase fluid includes an x-ray generator includes a sample chamber is configured to admit therein a sample of fluid for analysis. The chamber is disposed in a radiation path output from the generator. A filter is disposed in the radiation path between the output of the generator and the radiation input of the sample chamber. A first radiation detector is positioned in a radiation path from the sample chamber after radiation has passed through the sample chamber. A thickness and a material of the filter are selected to optimize resolution of radiation detected by the first detector to changes in volume fraction of oil and water in the fluid sample when a gas fraction thereof is between about 90 to 100 percent.

Abstract: Disclosed are an apparatus and method of filtering a narrow band X-ray. The apparatus includes a micro filter array to configure a plurality of micro filters in an array, a filter array storing unit to store a filter table having information about an angle of each of the plurality of micro filters within the micro filter array, and a control unit to retrieve the filter table to ascertain the angle of each of the plurality of micro filters. The control unit also controls an angle between each of the plurality of micro filters and a panel supporting the plurality of micro filters to be the ascertained angle, and filters and output a received broadband polychromatic X-ray to be the narrow band X-ray.

Abstract: A spectral purity filter includes a plurality of apertures extending through a member. The apertures are arranged to suppress a first wavelength of radiation and to allow at least a portion of a second wavelength of radiation to be transmitted through the apertures. The second wavelength of radiation is shorter than the first wavelength of radiation. The apertures extend though the member in different directions in order to be substantially in alignment with radiation constituting a non-parallel beam of radiation.

Abstract: The invention relates to x-ray filters in a collimator for controlling the energy of an x-ray beam along a projection axis in computed tomography systems. According to the invention, the filter assembly comprises a filter element for attenuating the x-ray beam, and at least a support plate which fixes the filter element. The filter element and the support plate are notch-shaped in the center part of the filter assembly along a direction perpendicular to the projection axis. The design may free space to be used by other collimator parts and further allows use of more than one filter element in a filter assembly for backup purposes. This simplifies replacement of a defective x-ray filter in the field.

Abstract: When generating a 3D image of a subject or patient, a cone beam X-ray source (20a, 20b) is mounted to a rotatable gantry (14) opposite an offset flat panel X-ray detector (22a, 22b). A wedge-shaped attenuation filter (24a, 24b) of suitable material (e.g., aluminum or the like) is adjustably positioned in the cone beam to selectively attenuate the beam as a function of the shape, size, and density of a volume of interest (18) through which X-rays pass in order to maintain X-ray intensity or gain at a relatively constant level within a range of acceptable levels.

Abstract: Methods for energy-sensitive computed tomography systems that use checkerboard filtering. A method of enhancing image analysis of projection data acquired using a detector configured with a checkerboard filter includes disposing in a system a detector to receive a transmitted beam of X-rays traversing through an object, where the system is configured so the detector receives both high- and one of total- and low-energy projection data; receiving the high- and one of total- and low-energy projection data at the detector; and then estimating an effective atomic number of the object and/or processing the projection data so as to mitigate reconstruction artifacts. The present invention has been described in terms of specific embodiment(s), and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appended claims.

Abstract: A computed tomography apparatus (10) includes spaced radiation sources (82, 84), such as anodes, which each propagate a cone-beam of radiation (40, 50) into an examination region (14). A detector (22) detects radiation which has passed through the examination region. An attenuation system (55) interposed between the radiation sources and the examination region for cone-angle dependent filtering of the cone beams. The attenuation system allows rays which contribute little to a reconstructed image to be attenuated more than rays which contribute more.

Abstract: An embodiment of the present invention discloses a method for producing projective and tomographic images using X-rays, allowing structures of similar composition to be imaged particularly well by combined evaluation of the behaviour of the test object with respect to the phase displacement during passage of the X-rays and its absorption. At least one embodiment of the invention also relates to an X-ray system and a CT system with respective source grids, phase grids, and analytical grids for carrying out the method.

Abstract: A detector array is disposed relative to a radiation source such that radiation from the radiation source over a predetermined time period is substantially similar across the detector array. The detector array includes radiation detectors operatively coupled to detector electronics. The radiation filter material is disposed at least partially between the radiation source and the detector array such that different portions of the detector array are exposed to radiation from the radiation source through either different radiation filter material thicknesses or different radiation filter material compositions during the predetermined time period. So configured, information regarding the radiation such as beam quality information for radiation pulses is collected and used to confirm the quality of the radiation source or to adjust data collected by the radiation system.

Abstract: Cast collimators for use in CT imaging systems are described, as are methods of making them. Such collimators may comprise pre-patient collimators, pre-patient filter/collimator assemblies, and/or post-patient collimators. The filters and/or collimators may be made of any suitable high-density, high atomic number material such as lead, a lead alloy, tantalum, tungsten, tungsten suspended in an epoxy matrix, tungsten suspended in a slurry, or the like. Embodiments of these collimators comprise specially-designed channels and vanes that allow them to be precision cast to the necessary degree of accuracy. These channels and vanes are preferably tapered. These collimators and filter/collimator assemblies help minimize the x-ray dose to the patient by minimizing the scattered radiation creation mechanism and by collimating out much of the scattered radiation that would otherwise be subjected to the patient.

Abstract: A multi-energy imaging system and method for selectively generating high-energy X-rays and low-energy X-ray beams are described. A pair of optic devices are used, one optic device being formed to emit high X-ray energies and the other optic device being formed to emit low X-ray energies. A selective filtering mechanism is used to filter the high X-ray energies from the low X-ray energies. The optic devices have at least a first solid phase layer having a first index of refraction with a first photon transmission property and a second solid phase layer having a second index of refraction with a second photon transmission property. The first and second layers are conformal to each other.

Abstract: An analog real-time signal processing device and method are presented. The device is configured to perform electrical signal processing. The device comprises an electronic circuit including at least one basic unit of electrodes, the basic unit being configured to be sensitive to an external field, such as input photon flux, indicative of a first input signal to cause emission of charged particles and configured to define at least one electrical input for a second input signal and one electrical output, thereby providing the electrical output in the form of an approximation of a product of the first and second input signals.

Abstract: It is described a filter (300) for at least partially compensating for an X-ray tube (10) the target angle heel effect and preserving the tungsten spectrum of the X-rays. The filter (300) has an anode side (302) and a cathode side (304), wherein the cathode side (304) has a higher attenuation coefficient than the anode side (302). The attenuation coefficient is determined to at least partially compensate for the target angle heel effect. The filter (300) is from the same material as an anode plate (110) or the anode (108) of the X-raysource (10) which is usually tungsten or a tungsten alloy.

Abstract: The present invention is directed to a method and apparatus of multi-energy data acquisition. An imaging system is also provided and includes a number of HF electromagnetic energy filters. The filters include at least a first and a second filter wherein the first filter is positioned in a path of HF electromagnetic energy when an HF electromagnetic energy source is energized to a first voltage and the second filter is positioned in the path of HF electromagnetic energy when the HF electromagnetic energy source is energized to a second voltage.

Abstract: The present invention is directed to a method and apparatus of multi-energy data acquisition. An imaging system is also provided and includes a number of HF electromagnetic energy filters. The filters include at least a first and a second filter wherein the first filter is positioned in a path of HF electromagnetic energy when an HF electromagnetic energy source is energized to a first voltage and the second filter is positioned in the path of HF electromagnetic energy when the HF electromagnetic energy source is energized to a second voltage.

Abstract: The invention relates to a beam filter (10) that can particularly be used in spectral CT-applications for producing a desired intensity profile of a radiation beam without changing its spectral composition. In a preferred embodiment, the beam filter (10) comprises a stack of absorbing sheets (111) that are separated by wedge-shaped spaces (112) and focused to a radiation source (1). Furthermore, the absorbing sheets have a varying width in direct ion of the radiation. Different fractions of the radiation source (1) area are therefore masked by the beam filter (10) at different points (A, B) on a detector area (2). The absorbing sheets preferably comprise a material that is highly absorbing for the radiation to be filtered.

Abstract: A small-sized filter unit of a simple structure, as well as an X-ray tube unit and an X-ray imaging system both having the filter unit, are implemented. A filter unit in a first aspect of the present invention comprises a filter plate, the filter plate having a first filter, a second filter disposed in a first direction with respect to the first filter and a third filter disposed in a second direction having a predetermined angle from the first direction with respect to the first filter, a guide plate having a guide frame for movement of the filter plate in the first and second directions, and a drive device for moving the filter plate.

Abstract: A shielding device (20) for optical and/or electronic apparatuses (16) is described, wherein said apparatuses may cooperate with incident electromagnetic radiation (X1, X2), in particular for space telescopes, the shielding device including: at least a filter (24, 26) provided for interacting with said incident electromagnetic radiation (X1, X2), for selectively filtering said radiation; and a support structure (22) for the filter. The support structure (22) is an inflatable structure, which is able to achieve an operating stand-by configuration, in which it is substantially folded together, and an active operating configuration, in which it extends along the longitudinal extension axis (ZZ), and is essentially completely unfolded. Furthermore, the filter (24, 26) includes a filter body, which is provided in order to be transversely positioned with respect to said longitudinal extension axis, when the support structure reaches its active operating configuration.

Abstract: An apparatus and method of attenuating radiation includes oscillating at least one fluid having a radiation attenuating property between at least two chambers, incident to applied radiation. The radiation attenuating device includes at least two communicating adjacent chambers, at least one fluid having radiation attenuating properties moveable between the at least two chambers, and a control circuit configured to oscillate the at least one fluid between the chambers.

Abstract: A container for preventing stealage of information recorded in a medium such as a card and compatible with security check conducted by X-rays at an airport or the like. A portable pouch is of a bag-like shape and produced by base clothes, on which a laminated film is laminated. The laminated film is a film including an aluminum foil layer and a resin layer laminated on each other. The aluminum foil layer is set up to have a thickness so as to transmit X-rays and an electromagnetic wave of an extremely high-frequency range and to shield an electromagnetic wave of a high-frequency range. The protection film shields an electromagnetic wave generated from a card and prevents leakage of the electromagnetic wave, thereby avoiding skimming. Further, the protection film transmits X-rays, thereby being compatible with X-ray check at an airport or the like.

Abstract: Passivation coatings and gettering agents may be used in an Extreme Ultraviolet (EUV) source which uses tin (Sn) vapor as a plasma “fuel” to prevent contamination and corresponding loss of reflectivity due to tin contamination. The passivation coating may be a material to which tin does not adhere, and may be placed on reflective surfaces in the source chamber. The gettering agent may be a material that reacts strongly with tin, and may be placed outside of the collector mirrors and/or on non-reflective surfaces. A passivation coating may also be provided on the insulator between the anode and cathode of the source electrodes to prevent shorting due to tin coating the insulator surface.

Abstract: An X-ray machine including a detector bank with high resolution detectors for imaging and low resolution detectors for CT reconstruction, and at least one X-ray source configured to direct a beam of X-rays impinging on both the high resolution and the low resolution detectors. A flux filter is located between the detector bank and the X-ray source and the flux filter includes attenuating material for attenuating a portion of the beam impinging on the low resolution detectors.

Abstract: A lifting drive for a radiation filter in a mammography device is provided. The lifting drive includes a recording apparatus that accommodates the radiation filter. The recording apparatus is embodied so that the radiation filter is operatively supported to allow movement for executing a lifting movement in at least one lifting direction. A first drive element is operable to create a drive movement. A first movement transmission element is operable to transmit the drive movement to the recording apparatus. The recording apparatus is operable to convert the drive movement into the lifting movement. A shape of the first movement transmission element is operable to be changed, so that the drive movement is able to be transmitted over different paths.

Abstract: An X-ray measuring instrument in which an object under examination is irradiated with X-rays, measurement data on the object is detected, a filter for adjusting the amount of transmitted X-rays is disposed between an X-ray source and the object, the relative position of the X-ray source to the object is varied, and the acquired measurement data is computed. The measurement data is subjected to logarithm transform to acquire projection data, and the amount of absorbed X-rays of the filter corresponding to the acquired projection data is determined. The thickness of the filter is computed by using a predetermined transform formula for the acquired amount of absorbed X-rays. A correction coefficient corresponding to the projection data acquired from the computed thickness of the filter is determined, and the projection data is multiplied by the determined correction coefficient. The projection data multiplied by the correction coefficient is restructure-computed to obtain a three-dimensional image.

Abstract: An X-RAY CONVERTER having a light-proof housing with an X-ray-transparent wall behind which there are fastened an X-ray-to-optical converter, a filter of residual X-radiation, an objective lenses unit, and a photodetector containing at least two optoelectronic converters with partly overlapping fields of view and separated electrical outputs for connection to a system for processing of fragmentary video signals and generating an integral output video signal.

Abstract: A lithographic apparatus includes an illumination system configured to condition a radiation beam, a projection system configured to project the radiation beam onto a substrate, and a filter system for filtering debris particles out of the radiation beam. The filter system includes a plurality of foils for trapping the debris particles, a support for holding the plurality of foils, and a cooling system having a surface that is arranged to be cooled. The cooling system and the support are positioned with respect to each other such that a gap is formed between the surface of the cooling system and the support. The cooling system is further arranged to inject gas into the gap.

Abstract: A small-sized filter unit of a simple structure, as well as an X-ray tube unit and an X-ray imaging system both having the filter unit, are implemented, A filter unit in a first aspect of the present invention comprises a filter plate, the filter plate having a first filter, a second filter disposed in a first direction with respect to the first filter and a third filter disposed in a second direction having a predetermined angle from the first direction with respect to the first filter, a guide plate having a guide frame for movement of the filter plate in the first and second directions, and a drive device for moving the filter plate.

Abstract: A detector apparatus is disclosed that includes a housing and a multilayer disposed within the housing. The multilayer defining a leading edge and a trailing edge and is adapted to interact with a plurality of high-energy photons, impingent from the leading edge, to permit passage of photons of at least one selected energy. The multilayer is secured to a first securement adjacent to the leading edge. The multilayer is secured to a second securement bracket adjacent to the trailing edge. At least one detector is disposed adjacent to the trailing edge of the multilayer to detect the impingent high-energy photons. An adjustment mechanism operatively connects to the second securement bracket to adjust the position of the second securement bracket, thereby altering an angular position of the multilayer.

Abstract: An x-ray source comprises a structured anode that has a thin top layer made of the desired target material and a thick bottom layer made of low atomic number and low density materials with good thermal properties. In one example, the anode comprises a layer of copper with an optimal thickness deposited on a layer of beryllium or diamond substrate. This structured target design allows for the use of efficient high energy electrons for generation of characteristic x-rays per unit energy deposited in the top layer and the use of the bottom layer as a thermal sink. This anode design can be applied to substantially increase the brightness of stationary, rotating anode or other electron bombardment-based sources where brightness is defined as number of x-rays per unit area and unit solid angle emitted by a source and is a key figure of merit parameter for a source.

Abstract: Disclosed are systems and methods for obtaining stereoscopic x-ray images. The method includes taking two digital x-ray views of the same object from differing positions. The included angle between the axes of the x-rays for each position generally coincides with that formed by a pair of eyes viewing the object, though larger angles can be used. The x-rays can be taken by two x-ray generators within a single housing or within separate but attached housings. The generators are spaced apart and aimed at the object to form the appropriate angle. Care is taken not to move the object. Preferably, the x-ray generators have dual collimators to take the views. In this case, the time between taking the two x-rays need only be as long as the image capture time of the sensor being used, which lessens the chance of the object moving.

Abstract: A heel effect compensation filter is configured to have a thickness distribution that uniforms an X-ray intensity angular distribution that is nonuniform in the body axis direction of a subject in an X-ray flux irradiated space. The space is formed by an X-ray flux diverging from an anode in a body width direction of the subject and diverging in a shape of an approximate sector in the body axis direction due to the heel effect, when the X-ray flux generated on the anode by irradiating a thermoelectron beam flux from a cathode to the anode is irradiated on the subject. The thickness distribution can be obtained using a predetermined formula.

Abstract: An XRF system, preferably handheld, includes an X-ray source for directing X-rays to a sample, a detector responsive to X-rays emitted by the sample, and a filter assembly with multiple filter materials located between the X-ray source and the detector. An analyzer is responsive to detector and is configured to analyze the intensities of X-rays irradiated by the sample at one power setting and to choose a filter material which suppresses certain intensities with respect to other intensities. A device, controlled by the analyzer, automatically moves the filter assembly to the chosen filter material and then the analyzer increases the power setting to analyze certain non-suppressed intensities.

Abstract: A method and an arrangement for an intelligent adaptive x-ray imaging system, in which the exposure conditions of the object to x-rays is dynamically controlled and optimized in real-time in order to provide the optimum diagnostic information. The arrangement splits the imaging beam into two separate fan beams that scan over the object in a single pass, where the first beam (scout) collects information from the object, that is analyzed to control the intensity or spectral quality or spatial distribution of the second beam (I-ImaS). The CMOS image sensors deployed in the arrangement are able to process detected information either on-chip or within a field programmable gate array, so as to compute a measure related to the diagnostic value of the information.

Abstract: A digital radiography system, having: a pixilated optical detector; and a mask positioned adjacent to the pixilated optical detector, the mask comprising a repeating pattern of first and second portions configured to pass different wavelengths of electromagnetic radiation therethrough such that a polychromic X-ray image can be taken using only a single X-ray exposure with a single imaging detector.

Abstract: An information processing apparatus includes a circuit unit, a front cover to support the circuit unit, a rear cover combined with the front cover with the circuit unit disposed therebetween, a skirt having a skirt body protruding from a surface of one of the front cover and the rear cover in a combining direction and an engaging slit formed on a surface of the skirt body in a horizontal direction of the combining direction, and an engaging protrusion having a protrusion protruding from a surface of the other one of the front cover and the rear cover to engage the engaging slit and a slant slanting to the surface of the other one of the front and rear covers from the protrusion.

Abstract: Devices and methods for implementing selective, or asymmetric, attenuation of an x-ray beam. In one example, a filter is provided that is substantially in the form of a wedge where some portions of the filter are thicker, and thus provide greater attenuation, than other, thinner portions of the filter. The filter is situated between the target surface of the anode and the x-ray subject so that x-rays generated by the target pass through the filter before reaching the x-ray subject. Specifically, the filter is oriented so that the thicker portion of the filter receives the higher intensity portion of the x-ray beam, while the thinner portion of the filter receives the relatively lower intensity portion of the x-ray beam. Thus, the gain profile of the x-ray beam is flattened so that the intensity, or flux, of the x-ray beam is relatively uniform throughout a substantial portion of the beam profile.

Abstract: An optic device, system and method for making are described. The optic device includes a first solid phase layer having a first index of refraction with a first photon transmission property and a second solid phase layer having a second index of refraction with a second photon transmission property. The first and second layers are conformal to each other. The optic device may be fabricated by vapor depositing a first layer and then vapor depositing a second layer thereupon. The first layer may be deposited onto a blank or substrate. The blank or substrate may be rotated during deposition. Further, a computer-controlled shutter may be used to alter the deposition rate of material along an axis of the optic device. Alternatively, the optic device may be moved at varying speeds through a vapor stream to alter the deposition rate of material.

Abstract: An X-ray flux irradiation intensity distribution which is nonuniform due to a heel effect can be made uniform, and a subject can be prevented from being unnecessarily exposed. In addition, image quality of image data obtained with an X-ray CT scanner can be made uniform and improved in a body axis direction. A heel effect compensation filter is configured to have a thickness distribution that uniforms an X-ray intensity angular distribution that is nonuniform in the body axis direction of a subject in an X-ray flux irradiated space. The space is formed by an X-ray flux diverging from an anode in a body width direction of the subject and diverging in a shape of an approximate sector in the body axis direction due to the heel effect, when the X-ray flux generated on the anode by irradiating a thermoelectron beam flux from a cathode to the anode is irradiated on the subject. The thickness distribution can be obtained using a predetermined formula.

Abstract: Numerous embodiments of a debris mitigation device are disclosed. One embodiment of the claimed subject matter may comprise a debris mitigation device for use in photolithography processes. In one embodiment, the debris mitigation device comprises a foil trap device. The foil trap device, in this embodiment, comprises a plurality of electrically conductive elements and one or more mounting devices, where the plurality of electrically conductive elements are coupled to the one or more mounting devices in such as way as to provide a space between one or more adjacent elements. In this embodiment, the elements are foil elements, and adjacent foil elements carry alternating potentials.

Abstract: An X-ray diagnosis apparatus is configured to control at least one of the X-ray diaphragm which restricts the irradiation range of the X-ray and the compensation filter which attenuates the amount of the X-ray based on at least one of the rotation position or the position parallel to the body axis of the X-ray source.

Abstract: The invention is directed to an x-ray flux management device that adaptively attenuates an x-ray beam to limit the incident flux reaching a subject and radiographic detectors in potentially high-flux areas while not affecting the incident flux and detector measurements in low-flux regions. While the invention is particularly well-suited for CT, the invention is also applicable with other x-ray imaging systems. In addition to reducing the required detector system dynamic range, the present invention provides an added advantage of reducing radiation dose.

Abstract: The object of the invention is to provide a transmission filter for EUV radiation which has a sufficiently narrow transmission window to characterize EUV radiation in a narrowly defined spectral region. This object is met by providing a transmission layer system having at least one uranium-containing layer.

Abstract: A narrow band x-ray filter can include: a substrate; and a sheaf of one or more reflection units stacked upon each other on the substrate. Each reflection unit can include: a first set of at least two discrete spacers on a respective underlying structures, a reflector disposed on the first set of spacers so as to form a void between the respective underlying structure and the reflector; and a first set of at least two discrete shims disposed on the first set of at least two spacers, each shim being at least substantially the same thickness as the reflector. A first device to produce a narrow band x-ray beam may include such a filter or an x-ray telescope. A second device to make an x-ray image of a subject may include the first device.

Abstract: An x-ray reflector may include: a substrate; a first layer formed on the substrate, the first layer including a relatively higher-Z material, where Z represents the atomic number; and a second layer formed on the first layer, the second layer including a relatively lower-Z material; at least one of the first layer and the second layer exhibiting a taper in an axial direction extending between a first end of the substrate and a second end of the substrate.

Abstract: A bowtie filter is constructed to have a fluidic envelope filled with attenuating fluid and a displacement insert that can present various x-ray attenuation profiles during a scan. The insert is designed to displace the attenuating fluid to achieve a denied attenuating or filtering profile. The insert can be rotated, twisted, moved, and otherwise contorted within the fluidic envelope as needed during the course of a scan. As the angle, position and shape of the zombie is changed, the x-ray profile of the filter changes. The insert may have a default shape when at rest, but can have its shape changed when external forces are placed thereon. As x-ray filtering needs change during the course of the scan, the insert can be compressed, stretched, and/or contorted to achieve additional filtering profiles.

Abstract: A radiation therapy system is provided having a radiation source for providing radiation for treating a patient, including treating skin cancer, wherein the radiation source features a filtering device that changes its filtering characteristic for filtering the radiation for treating the patient in response to a control signal. The filtering device includes two filters and a radiation blocker circumferentially arranged on a cylindrical member. The filtering characteristic is changed by rotating the filtering device in response to the control signal. The filtering device includes a driving unit for rotating the filtering device in response to the control signal in order to change its filtering characteristic, such as a motor with a gearing arrangement for coupling to a corresponding gearing arrangement on the filtering device. In this embodiment, the means for providing the radiation, i.e. the x-ray tube, is arranged inside the filtering device.

Abstract: Filters for EUV lithography, methods of manufacture thereof, and methods of filtering in an EUV lithography system are disclosed. The filter comprises a nanotube material layer sandwiched by two thin material layers that are highly transmissive and provide structural support for the nanotube material layer. The filter is supported on at least one side by a patterned structural support. The filter mitigates debris, provides spectral purity filtering, or both.

Abstract: The object of the invention is to provide a transmission filter for EUV radiation which has a sufficiently narrow transmission window to characterize EUV radiation in a narrowly defined spectral region. This object is met by providing a transmission layer system having at least one uranium-containing layer.

Abstract: A fastening device for a diaphragm for x-ray radiation has a base plate provided with an opening for the passage of x-ray radiation, the base plate being able to accommodate load forces, and at least one covering device which can be arranged for enclosure of a space on the base plate. A diaphragm can be housed in the space. A computer tomography apparatus embodies such a fastening device for a diaphragm.

Abstract: An DPP EUV source is disclosed which may comprise a debris mitigation apparatus employing a metal halogen gas producing a metal halide from debris exiting the plasma. The EUV source may have a debris shield that may comprise a plurality of curvilinear shield members having inner and outer surfaces connected by light passages aligned to a focal point, which shield members may be alternated with open spaces between them and may have surfaces that form a circle in one axis of rotation and an ellipse in another. The electrodes may be supplied with a discharge pulse shaped to produce a modest current during the axial run out phase of the discharge and a peak occurring during the radial compression phase of the discharge. The light source may comprise a turbomolecular pump having an inlet connected to the generation chamber and operable to preferentially pump more of the source gas than the buffer gas from the chamber.