2D Scanning Mirror Research Articles

A position sensing method for 2D scanning mirrors

This paper presents a cost-effective position sensing method for 2D scanning mirrors. The method uses only one 1D PSD (position sensitive detector) located at the backside of the 2D scanning mirror plate to retrieve the 2D rotation angle about the two axes separately in real time. Any 2D scanning mirror with resonant vibration about one axis and quasi-static vibration such as sinusoidal, saw tooth, triangular oscillation about the other axis can use this method. The two vibration axes are orthogonal to each other to form the scanning patterns, which are most desired in scanning 3D LiDAR systems. 3D scanning LiDAR is the targeted application for this research. The method uses timing measurement to measure the resonant vibration angle and Lagrange interpolation polynomial approximation to retrieve the quasi-static vibration angle. A prototype has been built to measure the 2D rotation angle of a 2D micromirror. The measured angle using the proposed method was verified using a 2D PSD. The largest errors for the vertical/horizontal angles were 9.6% and 5.36% respectively. The position sensing mechanism is also integrated to a scanning 2D micromirror based LiDAR system to demonstrate it as real time capability.

An infrared scanning and tracking system for detecting mid-wave infrared spectral characteristics of moving targets.

This paper presents the design and fabrication of an infrared scanning and tracking system for detecting mid-wave infrared (MWIR) spectral characteristics of moving targets. The infrared spectra and infrared image are integrated in this system, which is mainly composed of a two-dimensional (2D) scanning mirror, dual-band infrared lens, long-wave infrared imaging unit, MWIR spectrum-measuring unit, and processing-controlling unit. After describing the design specifications of this system, this paper analyzes the detection method and then describes how the tracking was realized by controlling the 2D scanning mirror. Experiments were carried out to verify its feasibility.

Pro/E-based design of infrared window of image-spectrum integrated instrument

In the paper, we proposed a Pro/Engineering-based (Pro/E-based) geometric design method of transmission window of infrared scanning system. Firstly, we established the 3-dimensional (3D) system model. Secondly, we assembled the 2-dimensional (2D) scanning mirror in the system according to its nine positions. Thirdly, according to optical path reversibility, we modeled two cylinders to respectively simulate the emitted and rejected rays. And the rejected cylinder intersects the shell to form a curve to indicate the scope of the incident ray. The geometrical parameters of the window can be determined by the smallest bounding curve of all nine intersecting positions. The successful development of the image-spectrum integrated instrument prototype verified its feasibility and correctness.

Controlling Software Design of 2D Scanning Mirror in Infrared Detecting and Tracking System

Firstly, this paper introduced infrared detecting and tracking system (IR D&T System) and several commonly used scanning solutions in IR D&T System briefly. Secondly, it analyzed how 2D scanning mirror works and PID (Proportion, Integration and Differentiation) algorithm. Thirdly, it introduced commands format and controlling method of the 2D scanning mirror used in image-spectrum integrated instrument developed by our group. And then it designed controlling software of the 2D scanning mirror using its secondary development package (SDK) and VC++. The software communicates with 2D scanning mirror through serial port. The MSCOMM serial communication control is used in communication software design. The controlling software is integrated to software of image-spectrum integrated instrument successfully and experiment results verified the correctness of controlling algorithm and engineering usability of the software.

A remote scanning Raman spectrometer for in situ measurements of works of art

In conservation science, one of the main concerns is to extract information from an artistic surface without damaging it. Raman spectroscopy has emerged in recent years as a reliable tool for the non-destructive analysis of a wide range of inorganic and organic materials in works of art and archaeological objects. Nevertheless, the technique is still mainly limited to the analysis of micro-samples taken from artistic surfaces. The development of an instrument able to perform non-contact analysis of an area of a few square centimeters aims to further increase the employment of this technique. This paper describes the development of a prototype Raman scanning spectrometer based on a diode laser, a 2D scanning mirror stage and a custom optical system, which can map a surface of 6 cm in diameter at a working distance of 20 cm. The device exhibits collecting optics with a depth of field close to 6 cm, which makes the Raman system suitable for the analysis of non-flat surfaces and three-dimensional objects. In addition, the overall dimensions and weight of the instrument have been limited in order to make the device transportable and, in principle, usable for in situ measurements. Details on the design of the device, with particular emphasis on the collecting optical system, and on results of the characterization tests carried out to assess its performances are reported. Finally, an example of an application involving the identification of pigments from a model painting is presented.

Novel piezoelectric actuation mechanism for a gimbal-less mirror in 2D raster scanning applications

In this paper, we present the design, fabrication and measurement results of a 2D scanning mirror actuated by 1 × 10 piezoelectric Pb(Zr,Ti)O3 (PZT) cantilever actuators integrated on a thin silicon beam. A combination of bulk silicon micromachining based on a silicon-on-insulator (SOI) substrate and thin-film surface micromachining on a 5 µm thick Si device layer is used to fabricate the device. Multi-layers of Pt/Ti/PZT/Pt/Ti are deposited as electrode materials. A large silicon mirror plate (5 mm × 5 mm) and a 1 × 10 PZT cantilever array arranged in parallel are formed after the backside release process. The ten PZT cantilever actuators are electrically isolated from one another. The device can operate in three modes: bending, torsional and mixed (or combinational) modes. In bending mode, the first resonant frequency was measured to be 30 Hz and an optical deflection angle of ±8° was obtained when all ten cantilevers were actuated at 9 Vpp. In torsional mode, the resonant frequency was measured to be 89 Hz and an optical deflection angle of ±4.6° was obtained by applying a gradually declining ac voltage started at 8 Vpp to two sets of actuators, where each set comprises five cantilever actuators of the said 1 × 10 array, i.e. 1–5 and 6–10. A 2D raster scanning pattern was achieved in the mixed mode when the bending mode was carried out by cantilever actuators of 4–7 and the torsional modes were exercised by two different sets of cantilever actuators, i.e. 1–3 and 8–10, under opposite biasing direction. This mixed mode operation mechanism demonstrates the first 2D raster scanning mirror-driven beam actuators.

Characterization of piezoelectric PZT beam actuators for driving 2D scanning micromirrors

A silicon micromirror driven by piezoelectric Pb(Zr,Ti)O 3 beam actuators has been demonstrated for two-dimensional (2D) scanning mirror applications. Two devices of similar design with different dimensions have been fabricated. The Si mirror is micromachined from the device layer of an SOI wafer, while the piezoelectric beam actuator contains multilayers of Pt/Ti/PZT/Pt/Ti/SiO 2/Si which is deposited and released from a SOI wafer. A 1 × 10 PZT arrayed actuator are separately arranged in parallel on a Si beam released from the SOI substrate after the micromachining process. The 10 PZT actuators are electrically connected in series. For the large micromirror device with mirror size of 5 mm × 5 mm, the first resonant frequency for bending mode was measured at 34 Hz, while the second mode, i.e., a twist mode or torsional mode, is measured at a resonant frequency of 198 Hz. For the small micromirror device with mirror size of 3 mm × 3 mm, the bending and torsional modes were observed at 122 Hz and 2.46 kHz respectively. 2D raster scanning patterns were illustrated for both micromirrors. dc superimposed bias effect was also investigated for both mirror sizes. With increased dc bias, larger deflection angles were obtained.