Portable wedge prism scanner for laser surface cleaning of corroded 304L stainless steel.

A compact wedge prism scanner for laser surface cleaning is proposed, wherein the concept of system was studied based on geometric analysis. The final equations for the design express the transposition of the laser beam focal point and scanning radius. The results were verified through comparisons to both Zemax simulation and experiments. There was satisfactory agreement between the equations and Zemax simulation, but slight disagreement with the experiments. Additionally, two main factors of wedge prism scanner in commercial laser removal applications (circumferential overlap and spot overlap) was also discussed and the completely corrosion removal experiment indicated the potential use of our scanner.

Non-back-reflecting polygon scanner with applications in surface cleaning.

Polygon mirror scanners are attracting considerable interest owing to their rapid speed and large scanning area. Here, we focused on the back-reflection effect of the polygon scanner. A new polygon scanner system was designed based on a geometric analysis. The final equations for the design express the position of the laser beam source having the largest scanning length without the reflected beam traveling back to the fiber. The proposed system performed a raster scan on an area. Additionally, a paint stripping experiment was conducted to demonstrate the potential use of our scanner in commercial laser cleaning applications.

Fabrication of a Hydrophilic Line on a Hydrophobic Surface by Laser Ablation Processing.

A hydrophilic line on a hydrophobic surface was fabricated by using plasma etching and laser ablation processing in this paper. We fabricated the nanospikes on a polyimide surface by using the plasma etching processing. CHF3 plasma treatment for hydrophobic coating was conducted on these nanospikes. We fabricated the microgrooves on the hydrophobic nanospikes surface using laser ablation processing. The microgroove had hydrophilic characteristics. In order to measure the hydrophilic characteristics of the microgroove, a solution that was dispersed with silver nanoparticles was used. The hydrophilic line on the hydrophobic surface was dipped in the silver nanoparticle solution. The silver nanoparticles were attached on the hydrophilic microgroove and not on the hydrophobic surface. We concluded that the laser heat affected zone should be reduced for reducing the hydrophilic line width. This hydrophilic pattern on the hydrophobic surface can be used for cell growth, protein manipulation, the spotting of biomolecules, micro-fluidics and water collection. This functional surface can especially be used for an electric flexible circuit, which is newly proposed in this paper.

High-speed, high-precision focal length measurement using double-hole mask and advanced image sensor software.

A cutting-edge precision technique for computation of focal length of a positive lens with double-hole mask is described. The technique is simple and versatile due to incorporation of the updated functions of image sensor device that supports reading the distance between beam spots instantaneously while the position of the specimen is being changed, as well as the reduction in several challenging measurement steps. Furthermore, this technique does not require prior knowledge of distances in the optical setup. High accuracy in focal-length measurement is obtained by precise beam spot distance analysis using image sensor integrated software. The acquired data exhibit considerably high precision and reproducibility.

Serial number coding and decoding by laser interference direct patterning on the original product surface for anti-counterfeiting.

Here, we investigate a method to distinguish the counterfeits by patterning multiple reflective type grating directly on the surface of the original product and analyze the serial number from its rotation angles of diffracted fringes. The micro-sized gratings were fabricated on the surface of the material at high speeds by illuminating the interference fringe generated by passing a high-energy pulse laser through the Fresnel biprism. In addition, analysis of the grating's diffraction fringes was performed using a continuous wave laser.

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

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.

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

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.

Design and Performance of a Focus-Detection System for Use in Laser Micromachining.

We describe a new approach for locating the focal position in laser micromachining. This approach is based on a feedback system that uses a charge-coupled device (CCD) camera, a beam splitter, and a mirror to focus a laser beam on the surface of a work piece. We tested the proposed method for locating the focal position by using Zemax simulations, as well as physically carrying out drilling processes. Compared with conventional methods, this approach is advantageous because: the implementation is simple, the specimen can easily be positioned at the focal position, and the dynamically adjustable scan amplitude and the CCD camera can be used to monitor the laser beam's profile. The proposed technique will be particularly useful for locating the focal position on any surface in laser micromachining.

Fabrication of microgrooves on a curved surface by the confocal measurement system using pulse laser and continuous laser.

In order to fabricate microgrooves on a curved surface, the curved surface was measured with a confocal system and then it was used for laser microprocessing. This paper proposes a new method of using a pulse laser for the confocal system to measure the curved surface. It also compares the conventional way of using a continuous laser and a new way of using the pulse laser with the confocal system. Using the data measured with the pulse laser for fabrication, microgrooves were fabricated on a curved surface. The width of the fabricated microgroove was 10 µm and the depth was 27 µm. The microgroove fabricated on a curved surface as a part of this study can be used in injection molding to manufacture a micropatterned plastic surface at a low cost. This plastic surface can be applied for a superhydrophobic surface, a self-cleaning surface, or a biochip.