Entrance Diameter Research Articles

Ultrasonic vibration-assisted grinding of quartz glass micro-hole

Quartz glass is extensively utilized in the aviation and biomedical fields. However, achieving high-quality ultrafine micro-holes on quartz glass is difficult because edge chipping and internal surface defects are prone to occur during processing. Therefore, the ultrasonic vibration-assisted grinding (UVAG) was proposed to realize efficient and low-damage precision machining of quartz glass micro-holes. First, the brittle-to-plastic transition depth and theoretical motion trajectory of a single grit of quartz glass in UVAG were analyzed. Subsequently, comparative experiments were conducted between UVAG and conventional grinding (CG) to machine quartz glass micro-holes. Finally, the influences of different parameters on grinding force, edge chipping, entrance and exit diameters, and internal surface quality were investigated. The experiments demonstrated that the grinding force, edge chipping at the entrance and exit, and internal surface roughness can be effectively reduced by UVAG compared to CG. After UVAG, the axial grinding force, size of the edge chips at the entrance and exit, and internal surface roughness decreased by 40.97 %, 36.28 %, 42.09 %, and 12.59 %, respectively. After optimizing the process parameters of UVAG, the size of edge chipping at the entrance and exit were 6.5 μm and 7 μm, respectively, and the internal surface roughness reached 0.146 μm. In this case, the diameter of the micro-hole was 112 μm, and had a depth-to-diameter ratio greater than 10.

Investigation on effect of cryogenic cooling on the hole-making of CFRP with conventional PCD tool and textured PCD tool

Carbon fiber reinforced polymer (CFRP) has obtained the widespread use in significant basic parts owing to its excellent properties. Different methods including the conventional PCD tool using dry machining (CPD), the conventional PCD tool with CO2 cryogenic cooling (CPC), and the textured PCD tool with CO2 cryogenic cooling (TPC), were introduced to investigated their effects on the holes-making performance. Results demonstrated that the obtained average entrance diameter and relative error of different spindle speeds using the CPC were about 4001 to 4005.4 μm and 0.025% to 0.65%, respectively. Dimensional accuracy and surface edge quality of entrance hole can be better improved by the CPC method. It was found that the cryogenic cooling method showed the remarkable effect in improving the anti-adhesion of tools than compared to the dry machining. Additionally, results indicated that the cryogenic cooling resulted in the significant fiber fractures and many pits inside the hole wall and the CPD method can help to improve the inner hole wall quality.

Reducing nest box entrance diameter impacts mammal occupancy

Tree hollows are an important resource for cavity‐nesting birdlife. When large, old trees are removed from a landscape, nest boxes are often installed as part of restoration efforts to replace lost natural cavities. If nest boxes are to be successful conservation tools, non‐target species, particularly competitive and predatory species, need to be prevented from entering nest boxes. Several different modifications to nest boxes aimed at excluding non‐target species have been trialed in previous studies. We tested the effectiveness of reducing the entrance diameter of nest boxes to exclude non‐target species in Southeast Queensland, Australia. We used restrictor plates to reduce the entrance diameter of nest boxes from 90 to 60 and 50 mm and compared the wildlife occupancy of nest boxes with these three entrance diameters. We found that Common brushtail possums, a predator of cavity‐nesting birds and eggs, were significantly less likely to occupy nest boxes with reduced entrance diameters and were excluded from nest boxes with a 50‐mm entrance diameter. Squirrel gliders occupied nest boxes with all three entrance diameters. Introduced species, namely the Common myna and the European honeybee, also occupied nest boxes with restrictor plates. Installation of nest boxes with reduced entrance diameters is a simple and effective strategy to exclude brushtail possums from nest boxes. However, a reduced entrance diameter cannot exclude other non‐target species, and we suggest that other exclusion strategies should be used in conjunction with reduced entrance diameters to increase the occupation of nest boxes by native birds.

A Cutting Force and Hole Geometry Study for Precision Deep-Hole Microdrilling of Magnesium.

Size effects, high thrust forces, limited heat dissipation, and tool deterioration are just some of the challenges that deep microdrilling poses, underscoring the importance of effective process control to ensure quality. In this paper, an investigation performed on a microdrilling process on pure magnesium using a 0.138 mm diameter microdrill to achieve an aspect ratio equal to 36 is proposed. The effect of the variation of the cutting parameters feed per tooth fz and cutting speed vc was studied on thrust force, supporting hole quality evaluation in terms of burr height, entrance, and inner diameters. The results showed that fz significantly influences the hole quality. In fact, as fz increases, the burr height decreases and the inner diameter approaches the nominal diameter. However, optimizing the hole geometry with high feed per tooth values increases the thrust forces, compromising tool life. In fact, a significant dependence of the thrust force on both cutting parameters was found. In this scenario, increasing vc can mitigate the high thrust forces by inducing material softening. The study results improve precision manufacturing by refining parameters, ensuring the quality and reliability of magnesium-based microcomponents.

Spray mist-assisted drilling of through silicon vias (TSV) using nanosecond laser: Influence of CNT nanofluid

Through Silicon Vias (TSV) are crucial in semiconductor technology for vertically connecting multiple stacks in 3D packaging. High aspect ratio, smooth and slightly tapered TSVs enhance layout efficiency and void-free filling. Being contact-less and dry-etching process, laser machining is a promising technique to fabricate TSVs. A percussion laser drilling approach was used to fabricate TSVs on a 500 μm thick silicon wafer with a 1064 nm ns laser. Four environments such as air, compressed air jet, water mist, carbon nanotube (CNT) fluid mist were employed to assess laser machining effects on TSV performance in terms of entrance and exit diameters, recast layer, side wall damage, and taper angle. Optimized process parameters (laser pulse energy and pulse number) were derived from an ANN prediction model. Laser drilling under CNT mist produced relatively circular (entrance diameter), straight, and clean TSVs. Reduced debris redeposition was observed under air jet, water mist, and CNT mist compared to air. Minimal sidewall damage occurred under water mist and CNT mist as compared to those machined in air and air jet. CNT mist yielded TSVs with less recast layer (∼7 μm), taper angle (∼1.05 deg.), and heat affected zone (HAZ) thickness (∼50 μm). Enhanced machining quality may be attributed to increased thermal conductivity of CNT nanofluid and pressurized mist flow rate, improving cooling and debris removal. Furthermore, a detailed investigation of TSV using SEM was performed and the findings were compared to those of other research groups.

Mechanisms and characterization of a novel hybrid laser-enhanced particle laden electrochemical fabrication process for high quality micro-dimples on germanium wafers

The first-generation semiconductor materials represented by silicon (Si) and germanium (Ge) still hold a dominant position in many fields, including micro-electromechanical systems (MEMS) and integrated circuits (ICs). The processing of these materials continues to attract significant research attention for improvements in quality and efficiency. This study proposes a novel hybrid laser-enhanced particle-laden electrochemical machining (LEPL-ECM) process, whereby pulsed laser irradiation is utilized to selectively and locally enhance the electrical conductivity of Ge at specific locations. A neutral electrolyte jet, containing abrasive diamond particles, is applied to the location on the wafer surface opposite the laser irradiation, facilitating a localized and enhanced electrochemical dissolution. The effect of micro-particle erosion effectively removes the generated oxides and potential passivation layers, ensuring continuous and efficient electrochemical reactions. Consequently, high-quality micro-dimples with an entrance diameter of about 380–800 μm, a depth of around 138–300 μm, and a quasi-mirror surface with the roughness (Sa) of as low as 59.8 nm can be achieved within 90 s. Furthermore, the effects of the applied voltage, laser power and processing time on the resulting dimple characteristics and surface quality are discussed, along with a detailed morphology characterization. Dense micro-pits, radial streamlined micro-grooves and a special transitional region have been observed on dimple center, sidewall and near the edge, respectively, and the formation mechanism have been analyzed. Finally, a simulation of the electrolyte jet induced fluid pressure and velocity as well as the particle trajectory and distributions within and surrounding the dimple structure was conducted, which reveals that the synergistic mechanism associated with the hybrid material removal process involves both electrochemical corrosion and abrasive erosion.

Bionomical observations of Small Carpenter Bee, Ceratina smaragdula Fibricius (Hymenoptera: Apidae)

The small carpenter bee, Ceratina smaragdula Fibricius is a non-Apis pollinator of many economically important crops. The nesting biology, nesting preferences, architects, foraging, hibernation, and mating behaviour of this solitary bee were examined in this study. Fifteen nests of C. smaragdula were collected and examined for the targeted attributes. C. smaragdula highly preferred (>80%) the area of field sides in Ravenna grass (Saccharum ravennae) for making their nests, at a preferred height of 82.74 cm from the soil surface. The nesting of C. smaragdula along roadsides and houses was 30-60% and <30%, respectively. C. smaragdula hibernated during early October to February, broke hibernation in the first week of March and initiated mating immediately. The main reproductive period was from March to August and the first generation emerged from late April to early May. The peak insect population was recorded from June to August. The mean nest length, nest diameter, and nest entrance diameter were 11.15 cm, 0.79 cm and 0.53 mm, respectively. This bee preferred a single gallery, having 3-5 cells per gallery. The gallery contents are eggs, larvae, pupae and adults. The generation development period was from 4-5 weeks and 3-4 generations per year were existed. C. smaragdula started foraging early in the morning (7.27 am) and ceased in the afternoon at (4.51 pm). The average time of foraging per flower was 21.67 seconds, and the bees returned to the nest after 7.48 min of their first forage. These findings could be helpful in designing artificial nesting required for the preservation of C. smaragdula.

Comparison of drilling of Inconel 625 by AWJM and WEDM

PurposeThis study aims to comparatively analyze the cut parts obtained as a result of cutting the Ni-based Inconel 625 alloy, which is widely used in the aerospace industry, with the wire electro-discharge machining (WEDM) and abrasive water jet machining (AWJM) methods in terms of macro- and microanalyses.Design/methodology/approachIn this study, calipers, Mitutoyo SJ-210, Nikon SMZ 745 T, scanning electron microscope and energy dispersive X-ray were used to determine kerf, surface roughness and macro- and microanalyses.FindingsConsidering the applications in the turbine industry, it has been determined that the WEDM method is suitable to meet the standards for the machinability of Inconel 625 alloy. In contrast, the AWJM method does not meet the standards. Namely, while the kerf angle was formed because the hole entrance diameters of the holes obtained with AWJM were larger than the hole exit diameters, the equalization of the hole entry and exit dimensions, thanks to the perpendicularity and tension sensitivity of the wire electrode used in the holes drilled with WEDM ensured that the kerf angle was not formed.Originality/valueIt is known that the surface roughness of the parts used in the turbine industry is accepted at Ra = 0.8 µm. In this study, the average roughness value obtained from the successful drilling of Inconel 625 alloy with the WEDM method was 0.799 µm, and the kerf angle was obtained as zero. In the cuts made with the AWJM method, thermal effects such as debris, microcracks and melted materials were not observed; an average surface roughness of 2.293 µm and a kerf of 0.976° were obtained.

Non-invasive (georadar) investigation of groundhog (Marmota monax) burrows, Pennsylvania, USA

Zoogenic impact plays a critical role in stream processes, especially bank stability and resulting channel dynamics. This study focuses on bioturbation by groundhogs (Marmota monax) along the riparian zone of Mill Creek (Bucks County, Pennsylvania, USA). Several complexes comprising at least 32 active burrows (average diameter: 25.9 cm) were geolocated, with morphometric measurements obtained at selected sites. Two networks were imaged using high-frequency 800 MHz ground-penetrating radar (GPR) and included: 1) a grid of parallel 3-m-long transects on the south bank, and 2) an 11-m-long profile on the north bank. Post-processed electromagnetic signal traces (A-scans) comprising 2D radargrams (B-scans) revealed voids as reverse-polarity anomalies (hollow inclined shafts and tunnels), allowing for a general assessment of burrow depth and orientation. At the southern cutbank site, a large burrow had an entrance diameter of 0.3 m and a westerly dip. A sloping tunnel section was detected at ~0.5 m depth, based on the geometry of point-source (transverse) hyperbolic diffractions corresponding to the roof and a floor ‘pull-up’. The second locality traversed three open burrow entrances adjacent to large tree roots. This survey along a tributary channel shows multiple hyperbolics below adjacent openings, with the latter showing the characteristic signal ‘breakout’. GPR data show hyperbolic signatures ~0.3–0.4 m below the ground surface. Along this transect, burrowing activity appears to increase with proximity to the northern bank of Mill Creek. An example of a depth slice (bedding-plane view) from a nearby riverbank demonstrates the potential for 3D visualization (C-scans) of burrow networks using a grid of closely spaced GPR profiles. Groundhog burrows constrain maximum long-term level of the groundwater table and serve as important zoogeomorphic structures in diverse ecotones, including developed landscapes. Abundant evidence of bank slumping, incision, and treefall suggests that burrowing activity likely weakens root systems and enhances groundwater flow, thereby initiating or accelerating geomorphic cascades leading to slope failure.

Effects of water temperature on femtosecond laser layered-ring trepanning in superalloy with water-based assistance

The effects of the water temperature on the hole quality in water-assisted femtosecond laser layered-ring trepanning on superalloys were studied. The effects of the laser pulse repetition rate on the hole entrance/exit diameters, taper angle, and hole sidewall morphology and roughness at different water temperatures were compared and analyzed. The results show that at a water temperature of 70 ℃, the diameter of the hole entrance decreased, while that of the hole exit increased, compared with those at 20 ℃. Both the hole entrance and exit diameters decreased at 2 ℃. The hole taper angle was the largest when the water temperature was 20 ℃, followed by 2 ℃, and was the smallest at 70 ℃. When the laser pulse repetition rate was 300 kHz, the hole taper angle at 70 ℃ decreased by 43.6 % compared with that at 20 ℃. As the water temperature increased, the roughness of each part of the hole sidewall decreased. When the pulse repetition rate was 200 kHz, the quality of the hole sidewall improved under water-based assistance conditions, while the hole quality improved at a water temperature of 70 ℃, compared with drilling in air. As the water temperature increased, the water was more likely to evaporate, resulting in an increase in the amount of bubbles. As more bubbles moved upward, the water flow increased. The debris and materials generated by laser drilling were more effectively removed, thereby improving the drilling efficiency. The use of a higher water temperature was beneficial to obtain holes with smaller taper angles and a higher sidewall quality. The experimental results provide a reference for optimizing water-assisted femtosecond laser drilling. This methodology can be applied to the aerospace and semiconductor industries.

Experimental Investigation of the Machining Characteristics in Graphite-Powder-Mixed Electrochemical Discharge Machining of Microholes in Glass.

The effect of graphite powder on the machining characteristics in graphite-powder-mixed electrochemical discharge machining of microholes was still not clear. How the discharge mechanism changed with the addition of graphite powder into the electrolyte, which further led to changes in the morphology of the machined holes, remained to be revealed. In this study, a series of microhole machining experiments were conducted in glass. Comparisons of the discharge energy, microhole entrance diameter, hole taper, and tool electrode morphology after machining were made when machining in the electrolytes with and without graphite powder. Experimental results revealed that there were a lot of small pulse currents distributed on the current waveform when machining with the graphite-powder-mixed electrolyte. The average discharge energy of the small pulse current was 2.8 times as much as that of the general electrochemical discharge. After introducing graphite powder into the electrolyte, the entrance diameter of the hole became larger when the hole depth was deeper than 200 μm. The HAZ width increased with increasing hole depth at the voltage of 37-41 V, while it decreased at the voltage of 43 V. A reduction in hole taper angle with a range of 0.5° to 2.3° was achieved. In addition, after machining in electrolytes with and without graphite powder, the tool electrode surfaces showed different morphologies due to different discharges.

Comparative Study of Percussion Drilling in Glasses with a Femtosecond Laser in Single Pulse, MHz-Burst, and GHz-Burst Regimes and Optimization of the Hole Aspect Ratio.

In this contribution, we present a comparative study on top-down drilling in sodalime glass, with a femtosecond laser operating in single-pulse, MHz-burst and GHz-burst modes, respectively. We investigate the hole depth, drilling rate, and hole morphology for these three regimes while keeping the same experimental conditions. We demonstrate that, for both burst regimes, the burst length has to be adapted for optimizing the hole depth. In the GHz-burst regime, the lower the ablation rate the longer the holes. The three drilling regimes lead to different hole morphologies, where the GHz-burst mode results in the best hole quality featuring glossy inner walls and an almost cylindrical morphology. Furthermore, we obtain crack-free holes, the deepest measuring 3.7 mm in length and 25 µm in entrance diameter corresponding to an aspect ratio of 150, which is the highest aspect ratio reported thus far with femtosecond GHz-burst drilling to the best of our knowledge.

The effect of three-layer liner on the jet formation and penetration capability of shaped charge jet

In order to solve the problem of insufficient penetration ability of common liner, a new three-layer liner was proposed. AUTODYN software was used to simulate the efflux forming process of three-layer liner. The influence of four different impact impedance liner materials and different thickness ratio of three-layer liner on efflux performance was studied. In order to study the penetration ability of shaped charge to semi-infinite target plate, the penetration calculation of the target plate was carried out by taking several standoff under different thickness ratios. The optimal thickness ratio of three-layer liner was determined by studying the penetration depth and opening size of the target plate. The results show: By comparing the matching of liner materials with different impact impedances, the head velocity, effective length, total energy, total kinetic energy and effective jet mass of the jet formed when the three-layer liner material is AL 2024, copper and nickel from the outside to the inside are the best. In the analysis of the matching of the thickness ratio of the three-layer liner, the key to the jet forming is the thickness ratio of the outer liner. Within a certain range, the greater the proportion of the thickness of the outer liner, the better the jet forming; when the material of the three-layer liner is AL 2024-copper-nickel from outside to inside, the thickness ratio of the liner is 4/1/1 from outside to inside, and the jet forming is the best. The maximum penetration depth of the shaped charge with a thickness ratio of 1/1/4 from the outside to the inside of the three-layer liner is 395.5 mm, which is 52.3% higher than that of the shaped charge with a double-layer liner. Compared with the shaped charge with single-layer liner, the penetration depth is increased by 62.6%. When the thickness ratio of the three-layer liner is 1/1/4 from the outside to the inside, the maximum entrance diameter of the target plate is 14.3 mm, which is the same as that of the shaped charge with the double-layer liner. Compared with the shaped charge with single-layer liner, the entrance diameter is in-creased by 14.4%.

Dual-path micro-holes process for 0Cr17Ni7Al stainless steel thin plate with picosecond laser

Ultrafast laser is widely used in drilling micro-hole because of its excellent processing quality. However, when machining micro-holes with an aperture of fewer than 100 μm, the ultrafast laser drilling shows some drawbacks, such as poor roundness and taper of holes. This paper proposed a dual-path laser scanning strategy to solve the above-mentioned issues. A micro-hole with a diameter of about 90 μm was successfully fabricated on a stainless steel sheet with a thickness of 80 μm. In the dual-path laser scanning strategy, concentric circles were scanned layer-by-layer on the stainless steel sheet, quickly forming a through-hole. Then, a helical scanning path was conducted to reduce the taper of the hole. The effects of different laser ablation paths and angles of incidence (AOI) on micro-holes roundness, taper, and sidewall quality were illustrated. The experimental results showed that, through decreasing the AOI of the helical scanning path from 0° to −4°, the taper could be reduced to 2°, but the entrance diameter also increased. Furthermore, the radial ablation compensation was utilized to successfully reduce the hole-reaming phenomenon. The entrance and exit roundness error of the hole was between 0.2– 1.6 μm, and the taper could be reduced to 0.9°. In summary, the dual-path laser scanning strategy is an efficient and high-quality drilling method, providing a new laser drilling method for processing micro-holes in thin plates.

Transmission Efficiency Limit for Nonlocal Metalenses

AbstractThe rapidly advancing capabilities in nanophotonic design are enabling complex functionalities limited mainly by physical bounds. The efficiency of transmission is a major consideration, but its ultimate limit remains unknown for most systems. This study introduces a matrix formalism that puts a fundamental bound on the channel‐averaged transmission efficiency of any passive multi‐channel optical system based only on energy conservation and the desired functionality, independent of the interior structure and material composition. Applying this formalism to diffraction‐limited nonlocal metalenses with a wide field of view shows that the transmission efficiency must decrease with the numerical aperture for the commonly adopted designs with equal entrance and output aperture diameters. It also shows that reducing the size of the entrance aperture can raise the efficiency bound. This study reveals a fundamental limit on the transmission efficiency as well as provides guidance for the design of high‐efficiency multi‐channel optical systems.

Machinability of extruded and multi-directionally hot forged eco-friendly brass alloys

ABSTRACT Brass alloys assign a considerable portion of the industrial components’ material due to their outstanding characteristics. These materials are manufactured using hot forging or extrusion techniques, according to the application for different purposes. In this work, the metallographic and mechanical characteristics of three environmentally friendly brass alloys – CuZn40Pb2 (CW617N), CuZn38As (CW511L) and CuZn21Si3P (CW724R) – extruded and multi-directionally hot forged have been examined. By focusing on the flat bottom drilling operation, the effects of the process and type of alloying have been investigated. The examination has been accomplished on experimental data about tensile strength, impact fracture energy, cutting forces, entrance and exit burr diameters, as well as hole quality. The findings demonstrate that the most crucial criteria impacting the machining outcomes are the presence of limited Pb element and material microstructural phases, their content and mechanical characteristics, as well as the type manufacturing process.

Electrochemical discharge machining of a high-precision micro-holes array in a glass wafer using a damping and confinement technique

Due to the unstable gas film, it is still a big challenge to achieve high repeatability and quality in electrochemical discharge machining (ECDM) of micro-hole arrays in glass. Based on our previous research on ECDM in micro channels, the present work uses a non-Newtonian fluid electrolyte (non-NTF electrolyte) in ECDM to further achieve a high uniform precision and quality micro-holes array in glass through the damping and confinement effect. The results revealed that an average entrance diameter of 343.8 ± 3.47 μm (mean ± standard deviation) and average heat-affected zone (HAZ) width of 18.01 ± 1.52 μm were successfully fabricated in a 300-μm-thick glass wafer. As compared to the conventional KOH electrolyte, the entrance overcut and the HAZ width of micro-holes were reduced by 43.84 %, and 64.81 %, respectively, while the repeatability improved by 67.92 %. The non-NTF electrolyte concentration and the tool rotation speed were also found to play a significant role in the damping and confinement effect, significantly affecting the geometrical properties of the micro-holes. Furthermore, the micro-holes array was filled with copper to form through glass vias (TGVs), and a standard deviation of the Kelvin resistance of TGVs was only 5.35 mΩ, further demonstrating an excellent repeatability and localization of ECDM micro-holes using a non-NTF electrolyte. The results illustrate that employing a non-NTF electrolyte is a simple way to increase the stability of the gas film and to improve the repeatability and localization of ECDM micro-holes.

Hole diameter variation compensation by integrating computation geometry for helical milling of stacked aerostructure

The stack-ups of composite and metal are used in aircraft manufacturing to produce modern high-performance aircraft, which makes fastener-hole-making more difficult. Helical milling is an advanced machining process to improve the quality of hole-making. This paper seeks to control the hole diameter error and guarantee fastener-hole fitting performance. The setup of automated helical milling for assembling composite/metal aerostructures is first presented. Meanwhile, the helical milling procedure in aircraft wing manufacturing is discussed. Based on the designed helical milling end-effector, a length-gauge-based feedback control mechanism of the orbital eccentricity is designed to reduce the diameter error of an intended fastener hole. For accurate measurement, a least-squares method is used to find the calibration parameters of the length gauge. Then the mathematical model of hole diameter variation extraction based on B-spline curve construction is given for further variation compensation. After that, the feedback control system of the radial feed mechanism is established. Besides, the modeling and compensation system of the hole diameter variation is developed and used. In helical milling of CFRP/Ti stacks in an aircraft assembly, fastener holes tend to achieve the target diameter of 7.9400 mm without extending the range of hole entrance and exit diameters.

A Deep-Hole Microdrilling Study of Pure Magnesium for Biomedical Applications.

The mechanisms of deep-hole microdrilling of pure Mg material were experimentally studied in order to find a suitable setup for a novel intraocular drug delivery device prototyping. Microdrilling tests were performed with 0.20 mm and 0.35 mm microdrills, using a full factorial design in which cutting speed vc and feed fz were varied over two levels. In a preliminary phase, the chip shape was evaluated for low feeds per tooth down to 1 μm, to verify that the chosen parameters were appropriate for machining. Subsequently, microdrilling experiments were carried out, in which diameter, burr height and surface roughness of the drilled holes were examined. The results showed that the burr height is not uniform along the circumference of the holes. In particular, the maximum burr height increases with higher cutting speed, due to the thermal effect that plasticizes Mg. Hole entrance diameters are larger than the nominal tool diameters due to tool runout, and their values are higher for high vc and fz. In addition, the roughness of the inner surface of the holes increases as fz increases.

Design of a single glass tube optical lens for soft X-ray laser decoherence

Laser has the advantages of high brightness, good monochromaticity, high coherence and good directionality, however, in some cases such as laser imaging and laser processing where only its high brightness or high monochromaticity is desired, the interference effect caused by high coherence can affect and limit its effective applications. In this work, a new single glass tube decoherence lens (SGTDL) is designed for soft X-ray laser decoherence through the simulation calculations. The simulation results show that an SGTDL with an entrance diameter of 5 mm, exit diameter of 0.6 mm and a length of 15 cm can effectively reduce the coherence of the X-ray laser with a wavelength of 10 nm and a beam waist radius of 1.25 mm. At the same time, the exit beam with a divergence range of 30–50 mrad is obtained at the SGTDL’s exit, and the transmission efficiency and gain in power density of the SGTDL are 78% and 52.74, respectively. For a laser beam with a wavelength of up to 1 nm, this model of SGTDL can maintain the transmission efficiency of the beam at more than 30%. This work also discusses the influence of the X-ray laser energy and the SGTDL’s length on the transmission performances of the SGTDL. The results show that the SGTDL designed according to the total reflection principle can meet the application requirements for laser decoherence in a range from the extreme ultraviolet to X-ray wavelength, and has a wide application prospect in X-ray laser imaging, laser processing, etc.