Y.D. Gokdel

Design and fabrication of two-axis micromachined steel scanners

This paper presents the fabrication and the test results of two-axis micromachined micro-mirror steel scanners developed for display and imaging applications. The novel fabrication method uses the conventional lithography and electrochemical metal etching techniques. A single photomask is used to define the whole structure, resulting in a simple and inexpensive fabrication process. Two different devices are designed, fabricated and characterized to test the proposed methods. Both of them employ the magnetostatic actuation to generate excitation force/torque. First device (Type-A) is a gimballed cantilever one, and it is capable of an optical scanning angle of 11.7° and 23.2° in slow- and fast-scan directions, consuming a power of 42 mW and 30.6 mW, respectively. This structure has a quality factor of 287 in the slow-scan direction and a quality factor of 195 in the fast-scan one. The second device (Type-B) is a gimballed torsional one, and it has an optical scanning angle of 76° and 5.9° in slow- and fast-scan directions, consuming 37 mW and 39 mW, respectively. This structure has a quality factor of 132 in the slow-scan and 530 in the fast-scan directions, respectively. The maximum total optical scanning angles obtained for the slow- and fast-scan axes are 105° (gimballed torsional device, Type-B) and 42° (gimballed cantilever device, Type-A).

A 3D Polymer Based Printed Two-Dimensional Laser Scanner

A two-dimensional (2D) polymer based scanning mirror with magnetic actuation is developed for imaging applications. Proposed device consists of a circular suspension holding a rectangular mirror and can generate a 2D scan pattern. Three dimensional (3D) printing technology which is used for implementation of the device, offers added flexibility in controlling the cross-sectional profile as well as the stress distribution compared to the traditional planar process technologies. The mirror device is developed to meet a portable, miniaturized confocal microscope application in mind, delivering 4.5 and 4.8 degrees of optical scan angles at 111 and 267 Hz, respectively. As a result of this mechanical performance, the resulting microscope incorporating the mirror is estimated to accomplish a field of view (FOV) of 350 µm × 350 µm.

LED integrated miniaturized polymer MEMS display

This study presents the process development and first experimental results of LED integrated polymer microelectromechanical systems (MEMS) for two-dimensional displays. Proposed integrated system is very cheap due to the fabrication simplicity and the choice of polymer material as the structural layer, and it is a strong candidate to show similar performance when compared with the existing flat panel displays. A process technology that enables the integration of the LED dies and the PCB-based MEMS structure is presented. The very first version of the MEMS structure is actuated by consuming 11.5 mW and resulting displacement is measured to be 9 mm. Along with the LED die size of 250 mum times 250 mum, 36 pixels of resolution can be achieved.

Toward fully three-dimensional-printed miniaturized confocal imager

Abstract. We present a disposable miniaturized confocal imager, consisting mostly of three-dimensional (3-D)-printed components. A 3-D printed laser scanner with 10×10  mm2 frame size is employed for Lissajous scan, with 180 and 315 Hz frequencies in orthogonal directions corresponding to ±8  deg and ±4  deg optical scan angles, respectively. The actuation is done electromagnetically via a magnet attached to the scanner and an external coil. A miniaturized lens with 6-mm clear aperture and 10-mm focal length is 3-D printed and postprocessed to obtain desired (≤λ/5 surface roughness) performance. All components are press-fitted into a 3-D-printed housing having 17 mm width, which is comparable to many of the MEMS-based scanning imagers. Finally, line-scan from a resolution target and two-dimensional scanning in the sample location were demonstrated with the integrated device.

Towards 3D printed confocal endoscopy

A low-cost confocal endoscope was developed consisting of a 3D printed laser scanner, a lens, and a housing. The developed tool, mainly made out of low cost polymer offers a disposable use. The scanner unit is overall 10x10mm and electromagnetically actuated in 2-dimensions using a magnet that is attached to the 3D printed scanner and an external miniaturized coil. Using 3D printer’s fabrication advantages the first two vibration modes of the scanner were tailored as out-of-plane displacement and torsion. The scanner employs lissajous scan, with 190 Hz and 340 Hz scan frequencies in the orthogonal directions and we were able to achieve ± 5° scan angles, respectively, with ~ 100 mA drive current. The lens which has 6-mm diameter and 10-mm focal length is 3D printed with Veroclear material and then polished in order to reach optical quality surface. Profilometer (Dektak) measurements indicate only x2 increase in rms roughness, with respect to a commercial glass lens having identical size and focal length.

Reliability of 3D-printed dynamic scanners

3D-printed dynamic structures have arisen as a lower cost and easier to fabricate alternative to miniaturized sensor and actuator technologies. Here, we investigate the reliability of a selected 3D-printed laser scanner, which was initially designed for miniaturized confocal imaging, having 1 x 1 cm2 footprint. The scan-line, 1st resonant frequency and quality factor of 3 devices were monitored for 100,000,000 (hundred million) cycles, and an average deviation of <6% was observed for all three parameters under investigation, for the devices under test. We conclude that 3D printed dynamic structures are promising candidates for a variety of applications, including optomedical imaging applications that demand disposable and low-cost scanning technologies.

System integration for real-time laser scanning confocal microscope

In this work, a laser scanning confocal microscopy system governed by a software controlled DAQ Card is presented. The presented system can be utilized for scanning a target and displaying the resulting image through a designed graphical user interface (GUI). The system performs two main operations: (1) generation of the actuation signal and (2) image acquisition. The architecture of the proposed system and successful operation of the system is demonstrated by constructing images from USAF51 negative resolution test target. In the experiments, the proposed system is operated at the slow scan frequency (fslow) of 1 Hz and the fast scan frequency (ffast) of 100 Hz with a sampling frequency (fs) of 20 kHz. The experimental results show that 1 μm lateral resolution is achieved in the proposed system.

Implementation of high-performance LSM using wavelet transformation analysis

Laser scanning microscopy (LSM), especially the laser scanning electron microscopy (LSCM) has become a technique which has been frequently used to acquire images of living cells with high resolution and contrast ratio in biomedical researchs including clinical biology. LSCM stands out as one of the most powerful microscopy techniques compared to conventional microscopy methods due to its capability of acquiring slices in the 3rd dimension by solely imaging the cell layers that lies only on focal plane. This study aims to increase the resolution of images by reducing the SNR of data which is obtained from resolution target by established confocal microscopy setup and subsequently using wavelet transform analysis.

RoboSantral: An autonomous mobile guide robot

RoboSantral, An autonomous mobile robot which has been designed and realized in order to guide the visitors through a university campus, is presented in this paper. This robot accompanies guests through the campus and gives presentations on predefined locations. Location data is obtained from GPS sensors. Targets such as faculty buildings, museums etc... are recognized by the image processing of pre-defined tags. As microprocessor and microcontroller, Raspberry Pi and Arduino are used respectively.

An electronic control and image acquisition system for laser scanning microscopy

This paper presents an electronic system that controls the entire operation of a laser scanning microscopy system through a DAQ card. Proposed system does not only create the required electro-coil driving signal peculiar to magnetically actuated micro-scanner that enables the raster-scanning movement, but also is responsible from the image acquisition part by both serially gathering the laser intensity data and using it to construct a meaningful microscopy image. Micro-scanner which is fabricated using Ni as the structural material is utilized in the system. The micro-scanners slow and fast scan frequencies are measured to be 250 Hz and 1560 Hz, respectively. Model of the DAQ card used in the system is NI-6356 which has maximum 5 mA current and 10 V voltage outputs. A power amplifier circuit with LM 386 is designed and added to the system for increasing field-of-view of the micro-scanner. The operation of the proposed system is demonstrated by acquiring data and constructing images from the USAF resolution target.