175 results about "Multiple pass" patented technology

A multiple pass self-cinching suture construct includes a strand of suture material. A fixed loop is formed at one end, and an adjustable loop is formed at the opposite end. A self-cinching section is disposed between the fixed loop and the adjustable loop. The self-cinching section includes a first pass of a tag end axially through the interior of the self-cinching section to form the fixed loop. The opposite tag end passes axially through the interior of two co-axial suture segments inside the self-cinching section, forming an adjustable loop. As the adjustable loop tag end is pulled, tension is applied and the self-cinching section constricts to maintain tension. In some embodiments, the self-cinching section includes at least four segments of the strand of suture material co-axially aligned along the self-cinching section.

Systems and techniques for establishing tool location in a well and conveyance line characteristics of a conveyance line accommodating the tool. The systems and techniques are directed at a closed loop manner of acquiring well location information. Thus, multiple pass detections of a well feature may be utilized to map, update and / or provide well location information in addition to conveyance line characteristic information in real-time. This may occur in absence of prior stored well mapping information or with supplemental information thereof.

The invention discloses a pipeline all-position multi-layer multi-channel TIG welding bead morphology measuring device and method, and relates to the technical field of intelligent welding. A molten pool image collecting module is used for collecting morphology information of a molten pool, and the light emitting end of a laser transmitter is used for facing a welding bead; the active and passive vision module is used for collecting an image of light emitted by the laser emitter projected on a weld pool groove and identifying a weld bead corner opening position and a weld bead width, and the active and passive vision module and the weld pool image collecting module are both electrically connected with the control module; the control module can fuse image features collected by the active and passive vision module and the molten pool image collection module, the axes of the molten pool image collection module, the welding module and the active and passive vision module are located in the same plane, and the molten pool image collection module and the active and passive vision module are located on the two sides of the welding module respectively. According to the method, manual participation in the welding process can be reduced, the welding automation degree is improved, and meanwhile, the welding bead morphology measurement accuracy is improved.

The invention provides a medical TA4G pure titanium wire bar and a preparation method thereof. According to the preparation method of the medical TA4G pure titanium wire bar, firstly, alloy raw materials are subjected to vacuum consumable smelting, a first alloy ingot is obtained, and then cogging forging is conducted; carrying out multidirectional forging and water quenching treatment on the blank; then the blank is subjected to precise radial forging; and finally, after multi-pass small-deformation hot rolling is conducted on the blank, cold rolling is conducted, annealing is conducted after cold rolling, and the medical TA4G pure titanium wire bar is obtained. According to the method, the oxygen content is limited, and the medical low-oxygen high-performance TA4G pure titanium wire bar is finally obtained through the processes of repeated vacuum consumable smelting, cogging forging, multidirectional forging water quenching treatment, multi-pass small-deformation hot rolling, cold rolling and annealing. The invention also provides the medical TA4G pure titanium wire bar prepared by the method provided by the invention.

The present invention belongs to the technical field of aluminum alloy materials, and specifically discloses a method for preparing cast-rolled 8021 alloy aluminum foil. The method comprises the following steps: producing an 8021 alloy billet with a thickness of 6-8 mm by casting and rolling; directly homogenizing annealing the billet without cooling; rolling the billet through a cold rolling production process; and then rolling the billet through multiple passes such as trimming, secondary annealing, and foil rolling to obtain the finished product thickness. Compared with the traditional direct-chill ingot hot rolling process, the method omits multiple steps such as hot-rolled plate ingot casting, ingot sawing and milling, uniform annealing, and hot roughing mill opening and rolling with a large processing capacity, thereby saving energy and reducing carbon dioxide emissions. The finished product has performance equivalent to or even better than that of a hot-rolled product, thus meeting customer needs.

The invention discloses a method for testing the filtering performance of a filter element under a simulated vibration working condition, which is characterized in that vibration parameters and filtering performance testing are combined for the first time through a test system by integrating a created vibration environment, so that the test environment is more vivid to an actual use scene, and the vibration effect of the filtering performance is synchronously and simultaneously detected; the device and the method help engineering technicians to improve the anti-vibration design of the filter element and master the filtering and purifying capacity of the filter element in actual use, provide reproducible verification support and a reliable scientific tool for actually evaluating the filtering performance and manufacturing quality of the filter element, and play a guiding role in promoting updating and upgrading of test standards in the filter industry.

Provided is a downhole tool, a well system, and a method for forming a well system. The downhole tool, in at least one aspect, includes a two part drilling and running tool, the two part drilling and running tool including a conveyance, a smaller assembly coupled to an end of the conveyance, and a larger bit assembly slidably coupled to the conveyance, the smaller assembly and larger bit assembly configured to slidingly engage one another downhole to form a combined bit assembly. The downhole tool, in accordance with this aspect, further includes a whipstock assembly coupled to the two part drilling and running tool using a coupling mechanism, and a hydraulically actuated anchoring assembly coupled to a downhole end of the whipstock assembly.

The invention relates to the technical field of steel pipe machining, in particular to an electric detonation lining composite steel pipe cold drawing device which comprises a rail box and an equidistant adjusting mechanism and further comprises four moving trolleys movably installed at the top of the rail box, three cold drawing dies are fixedly installed at the tops of the three moving trolleys correspondingly, and the inner hole diameters of the three cold drawing dies are sequentially decreased. And a clamp is fixedly mounted at the top of the other moving trolley. According to the method, the electric detonation lining composite steel pipe is subjected to multi-pass small-deformation drawing through the three cold drawing dies with sequentially reduced hole diameters, so that the electric detonation lining composite steel pipe is formed step by step, the single-time deformation can be effectively reduced, it is ensured that the electric detonation lining composite steel pipe is evenly stressed in the cold drawing process, lining stripping and damage are avoided, and the service life of the electric detonation lining composite steel pipe is prolonged. And the distance between the three cold drawing dies is adjusted according to the cold drawing requirement of the electric knock lining composite steel pipe, so that uniform distribution of drawing force is ensured, and lining stripping caused by local stress concentration is avoided.

Methods and systems for performing multiple pass optical measurements of semiconductor structures are presented herein. A measurement beam is incident on the surface of a semiconductor wafer more than once. In some embodiments, the measurement beam is incident multiple times at the same measurement site on the semiconductor wafer in an optical path between the illumination source and the detector. In some other embodiments, the measurement beam is incident at different measurement sites on the semiconductor wafer in an optical path between the illumination source and the detector. In these embodiments, an instance of the same nominal structure under measurement is fabricated at each different measurement site. In a further aspect, an optical modulation element is disposed in the measurement path. In another further aspect, multiple pass measurements using different combinations of optical modulation targets are combined in a multi-target measurement to further enhance measurement sensitivity and break correlations.

The invention relates to the technical field of drawing equipment, in particular to multi-pass wire drawing equipment. The multi-pass wire drawing equipment comprises a drawing cone pulley mechanism and a heating furnace, the drawing cone pulley mechanism comprises a cone pulley group, and a wire drawing die frame and a first guide wheel group which are sequentially arranged on one side of the cone pulley group; the cone pulley group comprises N cone pulleys which are arranged in parallel; the wire-drawing die frame comprises M wire-drawing dies; the wire is guided by the first guide wheel group, penetrates through the die orifice of the wire-drawing die, is wound on the cone pulley and is rewound on the first guide wheel group, and multi-pass drawing is performed by repeating the steps; wherein the total drawing pass is M, M is larger than or equal to 2, N is larger than or equal to 2 and smaller than or equal to M. Each cone pulley at least carries out one-pass wire drawing. The drawing cone pulley mechanism solves the problem that due to the fact that the number of drawing passes is increased, the sliding coefficient difference between the first pass and the last pass is too large, and wires are broken, and the drawing efficiency of a single machine is remarkably improved.

The invention discloses a high-surface-quality invar alloy cold-rolled steel strip and a manufacturing method thereof.The manufacturing method comprises the working procedures of acid pickling, cold rolling and pre-pressing, coping, cold rolling and rolling, cleaning, annealing, leveling, shearing and packaging, the surface of an invar alloy hot-rolled steel coil is subjected to acid pickling through a mixed acid solution, cold rolling and pre-pressing are conducted through three-pass cold rolling and rolling, and the surface quality of the invar alloy hot-rolled steel coil is improved. At least three pairs of grinding heads are adopted for grinding, the grinding frequency is not less than 3 times, multi-pass cold rolling is carried out after grinding, the number n of rolling passes meets the condition that n is larger than or equal to 0.5 * m + 1, m is the thickness of the ground cold-rolled steel strip, and the unit is mm. According to the method, the technical problems that the surface quality of the invar alloy cold-rolled strip is difficult to control, the requirement is high and the like can be effectively solved, invar alloy products with high surface quality and high plate shape requirement are prepared, and the high-surface-quality use requirement of a user is met.

The invention belongs to the technical field of titanium welding wire preparation, and discloses a preparation method of a low-cost low-hydrogen titanium welding wire. The method comprises the following steps: preparing a titanium alloy wire rod; under the room temperature condition, multi-pass continuous cold drawing operation is conducted on the titanium alloy wire rod, a plurality of drawing dies are detachably installed on the same continuous drawing machine or a plurality of continuous drawing machines connected in series, so that a wire material continuously passes through the multiple drawing dies at a time to complete multi-pass deformation, and the wire rod is subjected to continuous cold drawing. The pass deformation of the multi-pass continuous cold drawing is designed to be a starting stage, a middle stage and a final stage, and the single-pass deformation of the starting stage and the single-pass deformation of the final stage are smaller than the single-pass deformation of the middle stage; in the middle stage process or after the middle stage process, on-line annealing treatment is carried out on the wire, and on-line annealing is carried out under argon protection; and the wire material subjected to online annealing treatment is subjected to polishing and lower breaking or close arrangement treatment, and a titanium alloy welding wire finished product is obtained. The titanium welding wire prepared through the method is low in hydrogen content, high in preparation efficiency and low in cost.

The invention discloses a method for preparing an ultra-fine grain Ti-6Al-4V titanium alloy. The method comprises the following steps: pretreating a coarse-grain Ti-6Al-4V titanium alloy plate, processing the coarse-grain Ti-6Al-4V titanium alloy plate into square blocks with a specific proportion, and carrying out surface smoothing treatment; and then, forging deformation is implemented through multidirectional isothermal closed die forging, and the forging direction, the pressure and the deformation pass are controlled, so that the mixed crystal Ti-6Al-4V titanium alloy with the ultra-fine grain structure is prepared. After forging, the surface of a sample is cleaned, rolling preparation is conducted at the proper rolling temperature, and the thickness of the sample is reduced through rolling of multiple passes. The maximum grain size is smaller than 5 micrometers, the average grain size is smaller than 1 micrometer, and the proportion of grains within 1 micrometer reaches 75% or above. According to the method, the uniformity of a material structure is effectively improved, meanwhile, the service life of a mold is prolonged, the process efficiency and surface quality control are optimized, the mechanical property of the material is remarkably improved, and a new technical approach is provided for preparation of the titanium alloy material.

This application discloses a method and related equipment for online planning of welding gun posture for multi-layer and multi-pass external welding of pipelines. This method belongs to the technical field of intelligent welding and includes obtaining a laser line image and welding gun posture data of the pipeline welding groove; extracting characteristic pixel points from the laser line image; converting it into a three-dimensional point cloud by detecting a mathematical model and fitting it to obtain a three-dimensional welding groove diagram; using the three-dimensional welding groove diagram and welding gun posture data to calculate the welding groove size parameters, welding gun posture parameters, and the posture parameters of the workpiece to be welded, thereby determining the welding gun posture planning value; performing the current pass of filling welding along the welding groove according to the welding gun posture planning value, while simultaneously detecting and correcting the real-time welding gun posture value in real time; replanning the welding gun posture parameters during the return process; and after completing multiple passes of filling welding, controlling the welding gun to perform a cover weld on the welding groove to complete the pipeline external welding. It can be seen that this method can achieve better welding results.

The invention belongs to the technical field of friction stir additive manufacturing, and particularly relates to a method for eliminating a longitudinal gap between layers of a friction stir additive manufacturing component, which comprises the following steps of: assembling a stirring head on a main shaft of a friction stir additive machine, and starting a main machine, a wire feeder, a constant-pressure control system and a constant-temperature water cooling system of the friction stir additive machine; the stirring head is moved to the material adding starting point of the base plate, multi-pass deposition is conducted in sequence according to a set path, and a first layer of added materials is formed; the stirring head is lifted and moved to the material adding starting point of the second layer, material adding of the n layers is completed according to the set path, the deposition pass center line of the n layer deviates by a set distance relative to the deposition pass center line of the (n-1) layer, and a stirring needle of the stirring head can be inserted into the material of the (n-1) layer; by the adoption of the method, interlayer longitudinal gaps of the multi-channel and multi-layer additive component can be thoroughly eliminated, the Z-direction mechanical property is improved, a weak connection interface is avoided, the compactness of the component is improved, the production cost is low, and the efficiency is high.

The invention belongs to the technical field of rolling, and discloses a Ni / Al nano multilayer film electroplasticity and current-assisted ply rolling forming method. The Ni / Al multilayer film is an energetic material and is used as a brazing heat source and a welding flux. According to the method, millimeter-level Ni foil and Al foil serve as raw materials, the thickness ratio of all layers is determined according to the maximum self-propagating heat release amount, a six-roller precision rolling mill is used for conducting multi-pass electroplastic ply rolling under pulse current, the pass deformation is 60%, and electric pulse annealing is conducted after rolling (the temperature is lower than a reaction critical value), and the Ni / Al nanometer multilayer brazing thin film with the total thickness being 50 micrometers and composed of thousands of layers of nanometer thin films is prepared. The method overcomes the problems of low production efficiency, high cost, narrow application range and the like in the prior art, and compared with a magnetron sputtering method, the method is low in manufacturing cost, short in period, large in area and good in mechanical property; compared with an accumulative ply rolling technology, interface recombination is excellent, nickel layer breakage is light, and heat release is high; and the material is low in deformation resistance and good in plasticity, multi-layer film ply rolling forming property integrated forming is achieved, and industrial application is facilitated.

The present invention aims to disclose a processing process for ultra-thin calendered plain foil for electronic circuits, comprising the following steps: rolling a copper strip with a thickness of 0.15 mm to 0.2 mm through multiple passes to a first plain foil with a thickness of 6 μm to 20 μm; cleaning the first plain foil through two passes of a hydrocarbon degreasing agent solution; drying the cleaned first plain foil; and rolling the dried first plain foil through a wrinkle removal roller, wherein a first diagonal roller surface and a second diagonal roller surface are symmetrically arranged at both ends of the wrinkle removal roller, and the first plain foil is hood annealed to obtain a second plain foil. The beneficial effect is that the first plain foil is rolled after passing through the wrinkle removal roller, wherein the first diagonal roller surface and the second diagonal roller surface are symmetrically arranged at both ends of the wrinkle removal roller, and the middle part of the wrinkle removal roller is a smooth roller, and the wrinkled plain foil is flattened by the surface diagonal grooves of the first diagonal roller surface and the second diagonal roller surface, flattening is achieved while ensuring that most of the width of the ultra-thin calendered plain foil passes through the smooth roller, and the ultra-thin calendered plain foil is rolled up while eliminating wrinkles.

The invention relates to a weldless carriage bottom plate production process based on extrusion welding, and belongs to the technical field of extrusion welding, an aluminum alloy coiled material is firstly subjected to multi-pass rolling forming, wrinkling and cracking caused by one-time large deformation are avoided, a precision foundation is laid for follow-up triangular groove forming, then extrusion is conducted through a roller with a triangular cavity, and the weldless carriage bottom plate is obtained. Compared with a rectangular groove, the weldless compartment bottom plate solves the problems that lateral pressure resistance is weak and stress is easy to concentrate when a forklift forks, the pressure resistance is enhanced, a transition angle is formed in the third-pass sharp-corner finish roll extrusion forming process, the sharp-corner cracking risk is eliminated, and the service life of the compartment bottom plate is prolonged. The forking deformation resistance of the forklift is further improved; the top of the triangular groove is welded through laser welding, the problems that traditional welding has many defects and is low in strength are solved, defects such as air holes in a welding seam are reduced or closed through rolling operation after laser welding, residual stress is released, and the compactness of the welding seam is improved.

A method for controlling the structure uniformity of a large-size ultralow-expansion alloy bar comprises the following steps that (1) an ultralow-expansion alloy electroslag ingot with the diameter larger than that of the bar is heated to 1100-1130 DEG C, and heat preservation is conducted for 3-4 hours; (2) the heated electroslag ingot is subjected to multi-pass drawing-out and anvil forging rounding, and a cogging bar with the diameter being phi 330-phi 370 mm is obtained; (3) the surface of the cogging rod is subjected to sanding treatment, and then the cogging rod is fully coated with heat preservation paint; (4) the treated cogging rod is heated to 1050-1100 DEG C, and heat preservation is conducted for 2-3 hours; the upsetting ratio and the drawing-out ratio of the first time are controlled to be 1.3-1.6, the upsetting ratio of the second time is controlled to be 1.3-1.6, the drawing-out ratio is larger than 2.4, then rounding is conducted, a finished bar is obtained through water cooling, and (6) the radial thickness of the finished bar is removed by 10-20 mm through turning, and the finished large-specification ultralow-expansion alloy bar with the diameter being 230-250 mm is obtained.

An ohmic heater for the heating of a conductive fluid is comprised of a number of selectable electrodes, arrayed in such a way as to form a single pass-through from inlet to outlet. A series of flow conduits are provided to direct the flow across the faces of adjacent electrodes. The flow conduits are further configured such that the flow path makes multiple passes across the same adjacent set of electrode faces.

A multi-pass free forging punching method for deep blind holes in an engine cylinder block includes the following steps: jaw pressing, chamfering, pre-drawing, upsetting, wide anvil strong pressure drawing, rolling and drawing blanking, upsetting, step forming, pre-punching the blind hole in the first pass with a variable diameter punch, mechanically expanding the blind hole in the second pass, rolling forging and drawing, deep-drawing the blind hole in the third pass with a long punch, rolling forging and drawing, flattening the end face, and finishing the finished product. The blind hole forming process is controlled in multiple passes and stages, with the use of a variable diameter punch for pre-punching and mechanically expanding the blind hole, and a long punch for deep-drawing the blind hole. Furthermore, the forming effect is ensured by combining rolling forging and drawing and end face flattening processes. The multi-pass blind hole forming process can achieve staged shape control in each process, facilitate precise parameter control, suppress inner wall shrinkage, overcome the large inner wall shrinkage phenomenon of traditional punching methods, ensure fiber streamline integrity and dimensional reliability, and avoid the bottom folding phenomenon that is easily generated during traditional blind hole drawing. This method improves forging efficiency and provides more stable quality.

The present application relates to inkjet printing technology field, provide a jack shift inkjet printing method, inkjet vehicle includes multiple groups of nozzles, realize different color ink drawing, each group of nozzles includes multiple in Y direction on the arrangement, same color nozzle, nozzle is arranged into multiple rows in X direction, A nozzle and B nozzle are any two rows, the distance of A nozzle and B nozzle in Y direction is L, each nozzle includes multiple orifices, the distance of orifice in Y is delta, with a position on the printing platform as initial position, to solve the problem of improving graphic printing resolution in the premise of guaranteeing production efficiency and controlling printer cost in multiple PASS inkjet printing, the influence of color difference brought by different nozzles in printing process is reduced, the resolution of printing effect is improved by multiple coverage inkjet, the cost of using multiple groups of nozzles is reduced, the number of multiple PASS printing is reduced, and printing efficiency is effectively improved.

This disclosure provides a process for preparing fine-grained nickel-titanium shape memory alloy rods for medical use, comprising: forging a heated nickel-titanium alloy ingot through multiple passes, performing multiple high-temperature continuous rolling passes, and then performing thermomechanical treatment to obtain fine-grained nickel-titanium shape memory alloy rods. This invention, through a combination of specific multi-pass forging and strictly temperature-controlled high-temperature continuous rolling, utilizes a robust dynamic recrystallization mechanism to fundamentally refine and homogenize the austenitic matrix grains, and completely breaks down the continuous brittle Ti2Ni phase distributed along the grain boundaries into a randomly dispersed distribution, thereby obtaining fine-grained nickel-titanium alloy rods with high purity and excellent microstructure. This solves the practical problems caused by the coarse grains and brittle phase segregation of the original cast nickel-titanium alloy, such as easy intergranular fracture, difficult processing and forming, low yield, and poor fatigue life in medical applications.

The present application relates to a kind of metal matrix composite prepared by friction stir processing method, including the mixing of metal matrix composite reinforcement and substrate powder, according to the size of stir pin and shaft shoulder in the stir head of friction stir equipment, using milling cutter to open the groove on pure metal mold, the width is greater than the diameter of stir pin, the depth is greater than the length of stir pin;Reinforcement and substrate powder mixture is added to the groove and is maximized compaction, in the processing area of special friction stir welding machine, the center of stir pin of stir head is aligned with the center of groove, is prepared under the processing scheme of multiple passes variable stir head speed, obtains metal matrix composite at the groove of composite plate processing area, the obtained metal matrix composite reinforcement is uniformly distributed, and the mechanical and friction and wear performance is excellent.The present application can automatically prepare a variety of different kinds of metal matrix composite, without determining specific process parameters for different kinds of metal and reinforcement test, and is widely applicable.

The application relates to the technical field of heat sealing equipment, and discloses an inflating product processing heat sealing machine, which comprises a supporting table and a sliding frame, the supporting table is provided with a lifting table, the bottom of the lifting table is provided with an upper die, the sliding frame is slidably connected with a moving table, the moving table is connected with a lower die through an adjusting table, the adjusting table can adjust the angle and position of the moving table, a camera is arranged above the lower die, and the camera is connected with a visual positioning system. The inflating product processing heat sealing machine can roll and press the cloth through the extruding piece before heat sealing, can flatten the cloth, can reduce the probability of wrinkles near the weld, can discharge the air between the cloth layers, can avoid air gaps, can improve the heat sealing quality, can make the produced inflating product have good air tightness, and can stop at a predetermined position when rolling and pressing the cloth, can verify the positioning accuracy through physics and vision multiple times, and can improve the positioning reliability.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may perform a crest factor reduction on a radio frequency (RF) waveform in multiple passes, wherein the multiple passes each include: a clipping operation to reduce a peak-to-average power ratio (PAPR) associated with the RF waveform according to a threshold; and a filtering operation to remove at least a portion of out-of-band emission from the clipped RF waveform. The UE may transmit the RF waveform over a wireless channel, wherein the RF waveform transmitted over the wireless channel satisfies a spectral mask. Numerous other aspects are described.

The invention discloses a manufacturing method of an automobile high-strength steel part shaped like a Chinese character'ri 'based on laser rolling forming. The manufacturing method comprises the following steps that preparation work is completed; bending and forming the plate by using a robot; for the horizontally-arranged plate, the second end is sequentially bent vertically upwards, horizontally inwards and vertically downwards, so that the second end makes contact with the upper surface of the non-bent plate, and a closed rectangular pipe is formed; the first end is vertically and upwards bent and horizontally and inwards bent in sequence to form a C-shaped pipe, the first end makes contact with the outer surface of the bent position of the closed rectangular pipe, and closing is formed; laser filling wire fusion welding is carried out on the two connectors, and a closed pipe shaped like a Chinese character'ri 'is formed; and carrying out aerial fog shaping, cooling and straightening after welding. According to the manufacturing method, high-precision and low-resilience manufacturing of bumpers made of high-strength steel, ultrahigh-strength steel and light-weight materials can be achieved, the precision, strength and light-weight level of products can be improved, and meanwhile the industrial common problems that in a traditional technology, the number of passes is large, resilience is large, and energy consumption is high are solved.

The embodiment of the present application provides a hot rolling method for an aluminum alloy strip, comprising: a hot rolling step: rolling a strip billet in multiple passes in sequence through multiple racks, and the final hot rolling temperature is 360°C to 400°C; a cooling step: cooling the aluminum alloy strip after hot rolling through a cooling device to reduce the temperature of the aluminum alloy strip to no more than 320°C; a coiling step: coiling the aluminum alloy strip after the cooling step. In the embodiment of the present application, the aluminum alloy strip after hot rolling is cooled by a cooling device to reduce its temperature to a temperature not exceeding 320°C to avoid subsequent interlayer adhesion, black wire and black spot problems, so that the final hot rolling temperature can be controlled at 360°C to 400°C during the hot rolling process, thereby increasing the recrystallization temperature of the grains and making the grain distribution of the aluminum alloy more uniform, which is beneficial to increasing the proportion of cubic texture of the aluminum alloy and improving the deep drawing property of the material.

An optical parametric multi-pass apparatus for generating laser radiation through optical parametric amplification or generation converts pump radiation into signal and idler radiation. It includes a multi-pass device with multiple mirror elements arranged to provide several beam paths from an input section to an output section of the device. The input section receives pump radiation, and the output section delivers signal radiation as the generated laser output. At least one optically nonlinear crystal is positioned within the device to enable the parametric process using the pump radiation. The mirror configuration ensures multiple passes of the beam paths through the crystal. The device is further designed to filter along the beam paths so that idler radiation is suppressed after at least one pass. A corresponding laser apparatus and method for generating laser radiation are also described.

Methods and systems for measuring physical properties of a specimen by iterative solution of an optimization function including both current and prior measurement information are described herein. In one aspect, a Maximum A Posteriori (MAP) estimation approach is employed to integrate prior measurement information with current measurement information in the optimization function. In some examples, prior measurement information associated with the measurement of a semiconductor structure is available from a number of exogenous sources. In a further aspect, prior measurement information includes current measurements of a semiconductor structure under measurement as part of a multiple pass measurement. Prior statistics are determined based on an initial set of values of parameters of interest. The prior statistics are included in a subsequent MAP analysis of the same measurement data set employed in a first measurement pass. In another aspect, prior statistics are tracked to determine their impact on current measurements.