Realization of autofocusing system for laser direct writing on non-planar surfaces

Luo, Jianbo; Liang, Yiyong; Yang, Guoguang

doi:10.1063/1.4709407

Cited by 9 publications

(5 citation statements)

References 11 publications

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“…In particular, for the 3D processing of components and parts, an optimal process control of the working distance is fundamental 16 , 17 . Besides the direct approach of splitting the laser beam and measuring the partial beam with a sensor 18 , 19 , optical detectors can also monitor the process from a lateral position. The low light generation in micro laser machining with pulsed lasers and the positioning of the photodetector, at small working distance complicates this approach 8 .…”

Section: Introductionmentioning

confidence: 99%

Detection and analysis of photo-acoustic emission in Direct Laser Interference Patterning

Steege

Alamri

Lasagni

et al. 2021

Sci Rep

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Functional laser texturing by means of Direct Laser Interference Patterning is one of the most efficient approaches to fabricate well-defined micro textures which mimic natural surfaces, such as the lotus effect for self-cleaning properties or shark skin for reduced friction. While numerous technical and theoretical improvements have been demonstrated, strategies for process monitoring are yet to be implemented in DLIP, for instance aiming to treat complex and non-plane surfaces. Over the last 35 years, it has been shown that the sound pressure generated by a laser beam hitting a surface and producing ablation can be detected and analysed using simple and commercially available transducers and microphones. This work describes the detection and analysis of photo-acoustic signals acquired from airborne acoustic emission during DLIP as a direct result of the laser–material interaction. The study includes the characterization of the acoustic emission during the fabrication of line-like micro textures with different spatial periods and depths, the interpretation the spectral signatures deriving from single spot and interference ablation, as well as a detailed investigation of the vertical extent of the interference effect based on the ablated area and its variation with the interference period. The results show the possibility to develop an autofocusing system using only the signals from the acoustic emission for 3D processing, as well as the possibility to predict deviations in the DLIP processing parameters.

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Section: Introductionmentioning

confidence: 99%

Detection and analysis of photo-acoustic emission in Direct Laser Interference Patterning

Steege

Alamri

Lasagni

et al. 2021

Sci Rep

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“…More importantly, some other studies have already improved the optical setup to explore the focus on a non-planar sample based on diffractive beam samplers [ 12 , 13 ] or the macro/micro dual-drive principle [ 14 ]. Furthermore, many auto-focusing devices have been developed for laser direct writing [ 14 , 15 , 16 ]; laser ablation [ 17 ]; automatic microscopy and measurement [ 18 ]; laser material processing [ 19 ]; two-photon photo-polymerization (TPP)-based micro-fabrication [ 20 ]; and several other applications [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ] in Shack-Hartmann wave-front sensor fabrication [ 21 ], parallel data processing [ 22 ], photonic force microscopy [ 23 ], controllable mirror-lens retrofocus objective [ 24 ], tunable lens focal offset measurement [ 25 ], laser micromachining [ 26 ], remote sensing [ 27 ], automated optical inspection [ 28 ], auto-focusing infinity corrected microscopes [ 29 ], and direct imaging technology [ 30 ] with detailed theoretical models. However, these focus detection systems are complicated, expensive, and inadequate for the mass production of 3D patterns [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ].…”

Section: Introductionmentioning

confidence: 99%

In-Situ Real-Time Focus Detection during Laser Processing Using Double-Hole Masks and Advanced Image Sensor Software

Cao

Hoang

Ahn

et al. 2017

Sensors

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In modern high-intensity ultrafast laser processing, detecting the focal position of the working laser beam, at which the intensity is the highest and the beam diameter is the lowest, and immediately locating the target sample at that point are challenging tasks. A system that allows in-situ real-time focus determination and fabrication using a high-power laser has been in high demand among both engineers and scientists. Conventional techniques require the complicated mathematical theory of wave optics, employing interference as well as diffraction phenomena to detect the focal position; however, these methods are ineffective and expensive for industrial application. Moreover, these techniques could not perform detection and fabrication simultaneously. In this paper, we propose an optical design capable of detecting the focal point and fabricating complex patterns on a planar sample surface simultaneously. In-situ real-time focus detection is performed using a bandpass filter, which only allows for the detection of laser transmission. The technique enables rapid, non-destructive, and precise detection of the focal point. Furthermore, it is sufficiently simple for application in both science and industry for mass production, and it is expected to contribute to the next generation of laser equipment, which can be used to fabricate micro-patterns with high complexity.

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“…Profile measurement is determined by the quality of the focus condition [ 2 ]. A precision focus inspection system would also improve the reproducibility of current fabrication methods, such as direct laser patterning on non-planar surfaces [ 3 ], two-photon nanopatterning [ 4 ], and laser microgrooving using CCD cameras [ 5 ], and some other practical applications such as space cameras [ 6 ], remote sensing using time delay and integration CCD cameras [ 7 ], photonic force microscopy [ 8 ], optical scanning holography [ 9 ], and digital fundus photography [ 10 ]. In addition, several researchers are focused on the development of focus inspection techniques with various underlying principles and instruments such as diffractive patterns [ 11 ], a liquid-filled diaphragm lens [ 12 ], and the Moire principle [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

High-Speed Focus Inspection System Using a Position-Sensitive Detector

Cao

Hoang

Ahn

et al. 2017

Sensors

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Precise and rapid focus detection is an essential operation in several manufacturing processes employing high-intensity lasers. However, the detection resolution of existing methods is notably low. This paper proposes a technique that provides a rapid-response, high-precision, and high-resolution focus inspection system on the basis of geometrical optics and advanced optical instruments. An ultrafast interface position detector and a single-slit mask are used in the system to precisely signal the focus position with high resolution. The reflected images on the image sensor are of a high quality, and this quality is maintained persistently when the target surface is shifted along the optical axis. The proposed system developed for focus inspection is simple and inexpensive, and is appropriate for practical use in the industrial production of sophisticated structures such as microcircuits and microchips.

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Realization of autofocusing system for laser direct writing on non-planar surfaces

Cited by 9 publications

References 11 publications

Detection and analysis of photo-acoustic emission in Direct Laser Interference Patterning

Detection and analysis of photo-acoustic emission in Direct Laser Interference Patterning

In-Situ Real-Time Focus Detection during Laser Processing Using Double-Hole Masks and Advanced Image Sensor Software

High-Speed Focus Inspection System Using a Position-Sensitive Detector

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