Abstract: A laser processing device includes a height measurement unit configured to measure a vertical direction position of an irradiation point of a processing laser beam on an upper surface of a substrate; and a controller configured to control a vertical direction position of a light condensing unit based on the vertical direction position of the irradiation point while moving the irradiation point along multiple dividing target lines. The height measurement unit includes a coaxial laser displacement meter and a separate-axis laser displacement meter. The controller controls the vertical direction position of the light condensing unit by using only one of the coaxial or the separate-axis laser displacement meter for each of the multiple dividing target lines while the substrate is processed and performs a switchover of a laser displacement meter for controlling the vertical direction position of the light condensing unit between the coaxial and the separate-axis laser displacement meters.

Abstract: A bellows shaped spinal implant, comprising an upper plate, a lower plate and a bellows shaped shell extending between and joining the upper and lower plates. The bellows shaped shell is formed of titanium or an alloy comprising titanium and includes a wall extending therearound that defines a hollow interior. The wall has a thickness in the range of 0.5 mm to 1.0 mm to provide for radiographic imaging through the wall. The wall is angled or curved inwardly or outwardly between the upper and lower plates to provide stiffness mimicking the stiffness properties of a similarly sized polyetheretherketone (PEEK) implant. The upper and lower plates each comprise porous contact regions including a three-dimensional gyroid lattice structure defined by a plurality of struts and pores in communication with the hollow interior. The outer surfaces of at least a portion of the struts may comprise a laser ablated textured surface.

Abstract: A laser is used to controllably generate and propagate cleaves to produce a cleaved surface along the {111} crystallographic plane in diamonds.

Abstract: A contamination prevention irradiation device includes a generation unit and a mirror unit. The generation unit generates a laser beam. The mirror unit has a mirror surface for reflecting a laser beam. The laser beam reflected on the mirror surface is applied to a specimen disposed inside an objective lens. The laser beam is composed of a pulse train. Once a laser beam is applied to the specimen before observation of the specimen, deposition of contaminants on the specimen can be prevented for a predetermined subsequent period.

Abstract: Disclosed is a wireless communication terminal for performing communication wirelessly. The wireless communication terminal includes: a first wireless transceiver, which transmits/receives a signal through a first waveform; a second wireless receiver, which receives a signal through a second waveform different from the first waveform; and a processor.

Abstract: A method of processing a wafer having a plurality of intersecting streets on a face side thereof with protrusions on the streets includes a holding step of holding a protective sheet of a wafer unit on a holding table, an upper surface heightwise position detecting step of detecting a heightwise position of an upper surface of a reverse side of the wafer along the streets, and a laser beam applying step of applying a laser beam having a wavelength transmittable through the wafer to the wafer from the reverse side thereof along the streets while positioning a focused point of the laser beam within the wafer on the basis of the heightwise position, to thereby form modified layers in the wafer along the streets.

Abstract: An apparatus for manufacturing a display device includes: a stage unit; and a suction unit located above the stage unit, wherein the suction unit includes: a main body including an outer box with top and bottom openings and an inner cup disposed in the outer box; a first air blower disposed above the main body and including a first main pipe extending in a first direction and a second air blower including a second main pipe extending in a second direction intersecting the first direction; a lower plate coupled to a lower end of the outer box and including a through hole; and a suction inlet defined by an inner end of the lower plate defining the through hole and a lower end of the inner cup, wherein the suction inlet is opened downward.

Abstract: A system may include an emitting device and a controller. The emitting device may be adapted to emit a first laser beam and a second laser beam. The controller may include one or more processors and may be operably coupled to the emitting device to control emission of the first and second laser beams. The controller may be adapted to remove a portion of a workpiece to form an exposed surface of the workpiece with the first laser beam using the emitting device and to remove a portion of the exposed surface with the second laser beam using the emitting device.

Abstract: A diamond smoothing method of irradiating a laser light onto a raised and recessed surface of a diamond, so as to smooth the raised and recessed surface, by ablation that is caused to occur in the diamond by irradiation of the laser light onto the raised and recessed surface. The method includes: a threshold-energy-density detecting step of irradiating the laser light onto the raised and recessed surface, and changing an irradiation energy density of the laser light, so as to detect a threshold energy density as a lower threshold value of the irradiation energy density that causes the ablation to occur; and a smoothing processing step of executing a smoothing processing by irradiating the laser light onto the raised and recessed surface with a smoothing irradiation energy density that is set to be within a range from 1 to 15 times as large as the threshold energy density.

Abstract: A puncture forming method is a method of forming punctures in a sample by irradiating a surface of the sample with a light beam. The puncture forming method includes: forming a first puncture by irradiating a first position on the surface of the sample with a first pulse of the light beam; and after the forming of the first puncture, forming a second puncture which at least partially overlaps the first puncture by irradiating, with a second pulse of the light beam, a second position on the surface of the sample positioned away from the first position in a first direction. The second puncture has a tip which is positioned inside the sample and which is bent in a direction opposite to the first direction.

Abstract: In one embodiment, systems and methods include using an automated laser system to remove a portion of a coating for nutplate installation. An automated laser system comprises a laser scanner and a laser head, wherein the laser head is coupled to the laser scanner. The laser head comprises a containment unit and a vacuum connector wherein the vacuum connector is disposed on a first side of the containment unit. The laser head further comprises a camera system, a light source, a first actuator, and a second actuator all disposed on a top surface of the containment unit. The laser head further comprises an end piece, wherein the second actuator is configured to displace the end piece.

Abstract: In a method of manufacturing a photo mask, a resist layer is formed over a mask blank, which includes a mask substrate, a phase shift layer disposed on the mask substrate and a light blocking layer disposed on the phase shift layer. A resist pattern is formed by using a lithographic operation. The light blocking layer is patterned by using the resist pattern as an etching mask. The phase shift layer is patterned by using the patterned light blocking layer as an etching mask. A border region of the mask substrate is covered with an etching hard cover, while a pattern region of the mask substrate is opened. The patterned light blocking layer in the pattern region is patterned through the opening of the etching hard cover. A photo-etching operation is performed on the pattern region to remove residues of the light blocking layer.

Abstract: A method for processing a raster image file includes: receiving a raster image file comprising image data for a plurality of pixels, analyzing the image data of the raster image file, determining control data, and optionally at least one new raster image file, based on the analyzed image data, said control data being data for controlling settings of an imaging device so as to change the physical properties of generated imaged features corresponding with one or more of the plurality of pixels, and outputting the raster image file and/or the new raster image file, with the control data to an imaging device for imaging a relief precursor.

Abstract: Disclosed is a laser processing device including a laser light source configured to output laser light, a converging unit configured to converge the laser light toward a first surface to form a converging point, a camera configured to image reflected light of the laser light from the first surface, a spatial light modulator for modulating the laser light according to a modulation pattern, and a controller configured to execute acquisition processing of applying the laser light to the first surface by controlling the laser light source and imaging the reflected light by controlling the camera to acquire a reflectance of the first surface for the first wavelength.

Abstract: A manufacturing method of an electronic device is provided. First, a mother panel including a first flexible mother board, a second flexible mother board and at least one sealing material is provided, and the sealing material is disposed between the first flexible mother board and the second flexible mother board. Then, a separating process including a laser-cutting process is performed to cut the first flexible mother board into a first flexible substrate and to cut the second flexible mother board into a second flexible substrate. The first flexible substrate includes a first laser-cutting buffer region and a first edge. The second flexible substrate includes a second laser-cutting buffer region and a second edge. The sealing material is away from the first edge by the first laser-cutting buffer region and away from the second edge by the second laser-cutting buffer region.

Abstract: A gemstone includes: a table; a culet extending in parallel to the table and having an area at least 10% of a size of an area of the table; and a treatment covering at least the culet that reflects diffused light through the gemstone.

Abstract: Embodiments of the present application provide a method for preparing a sample for wafer level failure analysis. The method includes that: a plurality of splitting points are formed on a surface of a selected region of a to-be-analyzed sample along a preset direction, the plurality of splitting points being arranged in a straight line; and the to-be-analyzed sample is split by taking the straight line where the plurality of splitting points are located as a splitting line, to expose a cross section of a side surface of the to-be-analyzed sample and form the sample for the wafer level failure analysis.

Abstract: A bellows shaped spinal implant, comprising an upper plate, a lower plate and a bellows shaped shell extending between and joining the upper and lower plates. The bellows shaped shell is formed of titanium or an alloy comprising titanium and includes a wall extending therearound that defines a hollow interior. The wall has a thickness in the range of 0.5 mm to 1.0 mm to provide for radiographic imaging through the wall. The wall is angled or curved inwardly or outwardly between the upper and lower plates to provide stiffness mimicking the stiffness properties of a similarly sized polyetheretherketone (PEEK) implant. The upper and lower plates each comprise porous contact regions including a three-dimensional gyroid lattice structure defined by a plurality of struts and pores in communication with the hollow interior. The outer surfaces of at least a portion of the struts may comprise a laser ablated textured surface.

Abstract: A method for conditioning a welded vehicle body assembly is provided. The method includes welding the vehicle body member to at least one additional vehicle body member together to form the welded vehicle body assembly, the welded vehicle body assembly includes a weld area; and laser annealing a weld heat affected zone adjacent to the weld area to soften material in the weld heat affected zone.

Abstract: Panel level packaging (PLP) with high positional accuracy of dies. The PLP bonds dies accurately to die bonding regions of an alignment panel. High accuracy is achieved by providing die bonding regions with local alignment marks. Accurate die bonding on the alignment carrier results in a reconstructed wafer with accurate positioning of dies. The dies of the reconstructed wafer can be scanned by a die location check (DLC) scan based on sub-blocks of dies, enabling high DLC throughput. The DLC scan generates a DLC file with coordinate points of sub-blocks of the reconstructed wafer. Also, a laser direct imaging (LDI) file can be generated using sub-block circuit files aligned to the DLC file. The use of sub-block circuit files facilitates high throughput in generating the LDI file with high accuracy due to the reconstructed wafer being formed using the alignment carrier with local alignment marks.

Abstract: A method for producing microcracks in an interior of a composite structure includes: providing or producing the composite structure which has a solid body and at least one metallic coating and/or electrical components situated or provided on one side of the solid body, the solid body containing or being made of silicon carbide (SiC); and producing modifications in the interior of the solid body. Laser radiation is introduced into a flat surface of the solid body to cause multiphoton excitation which brings about plasma generation. The modifications are effected by the plasma in the form of a material transformation which generates compressive stresses in the solid body, thereby developing subcritical cracks in a surrounding area of a particular modification. The laser radiation is introduced into the solid body in pulses having an intensity which reaches a maximum within 10 ns after a start of a particular pulse.

Abstract: A laser engraving machine with a three-point suspension system and an inverted X-Y axis support system wherein the X-axis beam is to and mounted below the Y-axis beams and the Y-axis beams are mounted inwardly of the outer ends of the X-axis beam and are structurally integrated with the machine housing. In addition, a counterweight in the form of a second, independently activatable laser is added to the drive belt to reduce or eliminate vibration during rapid reciprocal movement of the tool during an engraving process.

Abstract: In a method for severing a solid body, a defined contour is stored in a control unit configured to detect contour breaches and to avoid contour breaches. A high-energy beam is moved along a contour on a surface of the solid body, with the surface of the solid body facing the high-energy beam, to produce with the high-energy beam a cutting gap. The contour on the surface is compared with the defined contour stored in the control unit, and avoidance of the contour breach is automatically deactivated when the contour on the surface of the solid body matches the defined contour and a contour breach is detected. Otherwise, the contour is omitted. Advantageously, the high-energy beam travels along the contour with an averaged line movement.

Abstract: A system and method for performing laser marking may include identifying an event performed by a laser marking system. A laser marking unit may be driven to mark the feature on the part. The part may be illuminated with a visible illumination signal to indicate an occurrence of the event in response to identifying the event.

Abstract: In one embodiment, a system including a tangible token comprising a single integrated transparent gemstone produced by fusing together a first transparent gemstone and a second transparent gemstone, a first internal side of the first transparent gemstone is etched with information pertaining to a blockchain, and the information comprises at least a private key, a public key, and an address, the first internal side of the first transparent gemstone is aligned with a second internal side of the second transparent gemstone, and the aligning encapsulates the information within a perimeter of the second internal side such that the information does not extend beyond the perimeter. The system includes a computing device that executes instructions to: read the information, validate, via a network and the address, the public key and private key are associated with the blockchain, and present an indication of whether or not the information is validated.

Abstract: A workpiece-separating device includes: a holding member that detachably holds a workpiece of a laminated body in which the workpiece that includes a circuit board and a supporting body through which laser beams pass are laminated with each other via a separating layer that peelably alters due to at least absorption of the laser beams; a light irradiation part that irradiates the laser beams toward the separating layer through the supporting body of the laminated body held by the holding member; a driving part that relatively moves a light irradiation position of irradiation from the light irradiation part with respect to the supporting body and the separating layer of the laminated body held by the holding member in at least a direction crossing a light irradiation direction of irradiation from the light irradiation part; and a controlling part that operates and controls the light irradiation part and the driving part.

Abstract: The invention relates to a processing centre (1) or cutting materials, consisting of a cutting machine (2a) and an adjusting device (5), wherein the adjusting device (5) has a positioning device (8), an illumination device (9, 9a) and an image sensor (11), wherein the positioning device (8) holds a tool unit (10) to be illuminated by the illumination device (9, 9a) in front of the image sensor (11) in such a way that the image sensor (11) is partially shaded by the tool unit (10), wherein the image sensor (11) has a greater maximum extension in at least one spatial coordinates direction than the tool unit (10) in the same spatial coordinates direction, and wherein the outline contour of the tool unit (10) is determined using the value for the extension of the shaded region.

Abstract: Systems and methods for machining openings of a component are provided. In one exemplary aspect, a laser system includes features for machining an opening into a component, such as a cooling hole for a CMC component of a gas turbine engine. The component can be oriented in a first position and lasered while oriented in the first position to form a portion of the opening. The component is then oriented to a second position and lasered while oriented in the second position to form another portion of the opening. The component is alternated between the first and second positions until the predetermined geometry of the opening is formed. The component is oriented in the first and second positions such that the laser beam can machine the component without clipping areas that are not desired to be machined.

Abstract: A laser processing device and a laser processing method are provided. The laser processing device includes: at least two lasers each configured to generate a laser beam; focusing members corresponding to the at least two lasers respectively and configured to adjust focus positions of at least two laser beams generated by the at least two lasers; and a beam combination member configured to receive the at least two laser beams whose focus positions have been adjusted, and output the at least two laser beams coaxially.

Abstract: A workpiece processing method includes holding a workpiece unit on a holding table and forming a division start point. The workpiece unit has a workpiece having a front side and a back side, and an additional member formed on the back side of the workpiece. The additional member is different in material from the workpiece. The workpiece unit is held on the holding table with the additional member opposed to the holding table. The division start point is formed by applying a laser beam to the front side of the workpiece with the focal point of the laser beam set inside the workpiece. The laser beam forms a modified layer inside the workpiece and simultaneously forming a division start point inside the additional member due to the leakage of the laser beam from the focal point toward the back side of the workpiece.

Abstract: One example of the disclosure provides a method of fabricating a chamber component with a coating comprising a yttrium containing material with desired film properties. In one example, the method of fabricating a coating material includes providing a base structure comprising an aluminum containing material. The method further includes forming a coating layer that includes a yttrium containing material on the base structure. The method also includes thermal treating the coating layer to form a treated coating layer.

Abstract: Example post-print processing of three dimensional (3D) printed objects are disclosed. An example system includes an energy source to apply energy to a selected portion of an outer surface of a 3D printed object. The energy provided by the energy source is to cause a polymer of the selected portion to melt and reflow. The selected portion and a non-selected portion of the outer surface to form a pattern on the outer surface of the 3D printed object. A controller to direct the energy of the energy source to the selected portion of the outer surface.

Abstract: The method and apparatus comprise the following features: —forming coil members (21) by bending an electric conductor (20) externally coated with an outer insulation (20?); wherein the bending is made at predetermined lengths from a reference position (16?), and wherein each one of the coil members (21), when formed, comprises at least one head portion (21?) and leg portions (21?) extending from said at least one head portion (21?); —feeding the electric conductor (20) to accomplish the bending; —cutting the electric conductor (20) to detach a formed coil member (21) from said electric conductor (20); —inserting the leg portions (21?) of the coil members (21) into slots of the stator, so that parts of said leg portions (21?) extend from one end of the stator and the head portions (21?) extend from an opposite end of the stator; —arranging at least one laser beam (13?a, 13?b) to remove the insulation (20?) from predetermined areas (20a, 20b) of the electric conductor (20); —radiating the surface of the electri

Abstract: Disclosed is a method for manufacturing stress-relief-annealing-resistant, low-iron-loss grain-oriented silicon steel, the method comprising: carrying out, by means of a pulse laser, scanning grooving on a single surface or two surfaces of a silicon steel sheet after cold rolling, or after decarburizing annealing, or after high temperature annealing or after hot stretching, temper rolling and annealing, and forming several grooves parallel with each other in a rolling direction of the silicon steel sheet, wherein a single pulse time width of the pulse laser is 100 ns or less, and a single pulse peak energy density is 0.

Abstract: A wire guide and a laser wire-processing device that includes a wire guide are provided. The laser wire-processing device includes a housing and an aperture in a side of the housing, wherein the aperture defines a longitudinal axis that is substantially perpendicular to the aperture. The laser wire-processing device also includes a backstop arranged in the housing and aligned with the longitudinal axis, the backstop defining a wire-contact surface in a facing relationship with the aperture. The laser wire-processing device also includes a wire guide arranged in the housing to manipulate a wire inserted through the aperture into a desired position relative to the longitudinal axis between the aperture and the backstop. The laser wire-processing device also includes a laser operable to direct a laser beam toward an insulation layer of the wire. The wire guide could be a tube arranged in the device or a backstop guide.

Abstract: A method of manufacturing a three-dimensional article includes: (1) Loading a metal platen into a build chamber, the metal platen defines an upper surface; (2) Performing concurrent processes including operating a movement mechanism to vertically translate the platen, operating a laser system to impinge a radiation beam upon the upper surface of the platen, and receiving a signal from an acoustic sensor that is positioned within the build chamber; (3) Analyzing the signal including determining a height of optimal laser convergence for the platen; and (4) Based upon the analysis, adjusting the laser convergence height to a build plane height.

Abstract: The invention relates to a method and a device for separating the excess glass (32) in the production of hollow glass products (12), wherein the method comprises: centring a hollow glass product (12) in a receiving device (10), which is designed to hold the hollow glass (12) and to rotate about a rotational axis in such a way that a separation line (24) along which the excess glass (32) is to be separated from the hollow glass product (12) to be produced is centred in relation to the rotational axis; processing the hollow glass product (12) in a plurality of positions along the separation line (24) by means of a laser beam in order to generate local filaments with a weakened glass structure during a rotation of the hollow glass product (12) about the rotational axis; and introducing energy along the separation line (24) in order to separate the excess glass (32) along the weakened glass structure.

Abstract: A method for encoding a plate-like workpiece comprising: defining an encoding area; applying a magnetic layer to the surface of the workpiece; fusing parts of the magnetic layer to the surface of the workpiece by acting on the workpiece with radiation within the encoding area; cooling the workpiece; removing the non-fused parts of the magnetic layer. The method permits the workpieces to be trackable in a simple manner, irrespective of surface treatments that may possibly be carried out or are to be carried out later.

Abstract: A laser machining apparatus includes: a laser beam emission device; a guide beam emission device; a scanner; a processor; and a memory. The memory stores a set of computer-readable instructions therein. The set of computer-readable instructions, when executed by the processor, causes the laser machining apparatus to perform: acquiring workpiece contour information specifying a contour of the workpiece; extracting a plurality of feature points from the workpiece contour information, each of the plurality of feature points being on the contour of the workpiece; generating a guide pattern indicating a setup position of the workpiece according to the plurality of feature points; and drawing the guide pattern with the guide beam by controlling the guide beam emission device and the scanner.

Abstract: Systems for processing a material by submerging the material in a fluid and directing laser pulses at the fluid and the material for processing the material. An embodiment removes the surface of concrete, brick, or rock or minerals in a relatively gentle, energy-efficient, and controlled manner that also confines the material that is removed.

Abstract: The invention discloses a laser engraving machine, comprising a casing, a processing platform, a laser engraving head, a laser emitter, and a red light projector, the platform is disposed in the casing, and has a lateral moving trajectory and a longitudinal moving trajectory; the longitudinal trajectory is disposed on one side of the platform, the lateral trajectory is spanned thereon; one end of the lateral trajectory is connected with the longitudinal trajectory, the other is engaged with the platform side; the head is disposed on the lateral trajectory and can move along it. The invention has reasonable structure and convenient use. By adding a working panel, the device can process hard and soft material products, meeting more requirements; by changing the external fan to the built-in fan and smoke exhaust chamber, the installation is simple, the exhaust effect is better, while the proportion of damage during transportation is reduced.

Abstract: Systems and methods here may be used for a setup of fluorescence image capturing of a gemstone, such as a diamond placed on a flat stage. Some examples utilize a setup that both sends light and captures the image from the table side of the gemstone by passing ultraviolet (UV) light between 10 nm and 400 nm to the gemstone and capturing the excited fluorescence image for analysis through a dichroic beam splitter. In some examples, the cutoff is 300 nm. The dichroic beam splitter arrangement allows for the camera to focus on the same interface of the stage and gemstone over and over for ease of use and without moving, changing, or adjusting the equipment for different samples.

Abstract: A laser device according to one embodiment of the present disclosure includes a light source and a reflection-type polarizer. The light source causes laser light to oscillate. The reflection-type polarizer is disposed on an optical path of the laser light and has a transmission axis coinciding with a polarization direction of the laser light.

Abstract: According to a method for manufacturing a hologram pattern of the present invention, the hologram pattern is applied to a metal plating layer (not a metal specimen). Accordingly, materials which can be plated are widely applicable. The hologram pattern, which becomes appeared in various colors depending on light and user's vision, can be formed with a simple process.

Abstract: A method and a device for processing a unidirectional flow surface, the method includes: generating a grayscale map having gradually changed grayscale values; generating a holographic phase map having a bionic light spot with gradually changed energies based on the grayscale map; loading the holographic phase map onto a spatial beam shaper; and focusing a laser beam on a surface of an object to be processed after the laser beam passes through the spatial beam shaper, to process structural units having unidirectional flow characteristics on the surface of the object to be processed.

Abstract: Laser finishing of apparel products allows an operating model that reduces finishing cost, lowers carrying costs, increases productivity, shortens time to market, be more reactive to trends, reduce product constraints, reduces lost sales and dilution, and more. Improved aspects include design, development, planning, merchandising, selling, making, and delivering. The model uses fabric templates, each of which can be used to produce a multitude of laser finishes. Operational efficiency is improved.

Abstract: According to the present disclosure, methods and systems for producing a microscale optical code on a precious object and reading the microscale optical code are disclosed. The method comprises the steps of providing an object, providing at least one marking unit, inscribing an array of micro-indents or micro-holes on the at least one surface of the object using at least one marking unit and generating a two-dimensional data matrix with the array of micro-indents or micro-holes. The two-dimensional data matrix has a plurality of rows and columns. The method further comprises generating a microscale optical code comprising the two-dimensional data matrix and additional four corners. The two-dimensional data matrix represents a binary code matrix of number 1 and 0 in the plurality of rows and columns with each micro-indent or micro-hole forming the binary number 1 and spot with no indent or hole forming binary number 0.

Abstract: A display device including: a display panel; a polarization film disposed on the display panel; and a reflective layer disposed on the polarization film, wherein the reflective layer is disposed between a first hole and a first groove, wherein the first hole passes through the display panel and the polarization film, and the first groove is provided in the display panel around the first hole.

Abstract: A method for manufacturing a decorated-part comprises a first and second base coat-layer-forming process, a surface coat-layer-forming process and a laser-decorating process. In the first base coat-layer-forming process, the first base coat-layer colored in a highly light color at a lightness-level of 70 or more is formed on the surface of the resin base-material 12. In the second base coat-layer-forming process, the second base coat-layer 21C colored in a chromatic color is formed on the first base coat-layer. In the surface coat-layer-forming process, the surface coat-layer colored in a less-bright color at a lightness-level of 20 or less is formed on the second base coat-layer 21C. In the laser-decorating process, the first laser-processed groove penetrating the surface coat-layer and exposing partially the second base coat-layer is made by irradiating the infrared laser onto such surface coat-layer, thus providing a fine decoration onto the surface of said decorated-part.

Abstract: A photoacoustic device for detecting gas includes a photoacoustic cavity having a side wall extending between a first end and a second end and having an outer surface; a light source suitable for emitting a modulated light radiation, and coupled to the first end; a microphone coupled to the side wall, the photoacoustic cavity being made of a material transparent to the light radiation of the light source; a mirror being arranged on at least one portion of the outer surface of the side wall; and the side wall having a thickness chosen as a function of the depth of penetration ? of a thermal wave coming from the mirror into the transparent material.