USABILITY OF CERAMIC STRUCTURES FOR POSITIONING OF OPTICAL MICRO ELEMENTS

Transcription

1 USABILITY OF CERAMIC STRUCTURES FOR POSITIONING OF OPTICAL MICRO ELEMENTS Holger Neubert, phone:

2 Fraunhofer Institute for Ceramic Technologies and Systems IKTS Regular staff ~ 600 Operating budget 54 million euro Dresden branch Industrial revenues 16,3 million euro Certification DIN EN ISO 9001, 14001, Hermsdorf branch Institute director Prof. Dr. Alexander Michaelis Dresden-Klotzsche branch

3 Fraunhofer Institute for Ceramic Technologies and Systems IKTS Structural ceramics Functional ceramics Materials Sintering and Characterization Energy Systems, Bioand Medical Engineering Processes and Components Environmental and Process Engineering Smart Microsystems

4 Smart Materials and Systems Materials Component Technologies System Integration Applications Material Synthesis Ferroelectric, piezoelectric, dielectric ceramics Antiferroelectric materials Pb free piezoelectrics Electrocaloric materials Ceramic targets for PVD, PLD Powder Powder pressing Paste Screen printing Thick film Slurry Tape casting Soft-Mold technology Fiber spinning Composite Fiber composites Dice and Fill Actuators Adaptive mirrors Micro-positioning stages Sensors/Harvesters Load cells Piezo generators US Transducers NDT/medicine Particle manipulation Condition Monitoring US inspection Acoustic emission Guided waves techniques Wind turbines, Offshore foundations Aircraft structures, Pipelines, tanks, containers

5 Components Powder Binder solution Granules Paste Slurry Powder pressing Screen printing Slip casting/tape casting Fiber spinning Bulk ceramic Thick film µ-structure, tape/multilayer Fiber/composite

6 Integrated Piezoceramic Components Screen printing technology Cost-effective manufacturing Wafer-level fabrication Microsystems integration High precision, fine structures Strong interface reliability Blade Thick film paste Frame Screen Substrate

7 Integrated Piezoceramic Components PZT Thick film properties Thickness µm Structure dimension 100 µm Homogeneous and dense microstructure Typical properties on Al 2 O 3 33T / 0 = 1900 d 33 = 210 pc/n R iso = Ωm Substrates Alumina, Zirconia LTCC, HTCC Silicon Steel grades Applications Sensors Actuators Ultrasound transducers Force Sensor Pressure Sensor Positioning Stage Deformable Mirror 2D US-Transducer Array Single Element US-Transducer

8 Actuators for Adaptive Mirrors LTCC material: DP 951 Membrane thickness: 220 µm Membrane Diameter: 34.7 mm Frame thickness: 660 µm PZT Film thickness: 100 µm Cu thickness: 150 µm Au Electrodes PZT Thick Film LTCC Substrate Cu Metallization Rear side: PZT thick film on LTCC Front side: electroplated Cu

9 Actuators for Adaptive Mirrors Experimental Results: All electrodes, E = 0.75 kv/mm 2kV/mm: l = 45 µm Resonance frequency: f = 1.45 khz Shaping of wave fronts in wide range proved Middle electrode, E = 0.75 kv/mm One electrode in 2nd raw, E = 0.75 kv/mm C Reinlein et al., J. Micro/Nanolith. MEMS MOEMS 12(1) , 2013

10 Micro-Positioning Stages for Optical Applications Classical plenoptic camera Micro-lens array set into focal plane of main lens Captures 4D light field information of a scene Allows for depth maps / 3D-images / post exposure of focal plane Innovative Plenoptic camera Micro-lens array set out of focal plane of main lens Micro-lens array actuated Continuous adaption to object distance Capture of several images taken at different positions of the micro-lens array Improved spatial resolution object main lens microlens array lens array micro- intermediate image image image plane plane plane

11 Micro-Positioning Stages for Optical Applications Two bending modes by different electrode design d 31 : through-thickness excitation / in-plane contraction d 33 : in-plane excitation / in-plane elongation 100 µm µm t = 15 µm + Top electrode E-Field PZT thick film Bottom electrode - Substrate t = 15 µm electrode distance electrode width 100 µm µm + - E-Field PZT thick film Substrate D Ernst et al., Advances in Applied Ceramics, 114 (2015)

12 Micro-Positioning Stages for Optical Applications Two bending modes by different electrode design d 31 : through-thickness excitation / in-plane contraction d 33 : in-plane excitation / in-plane elongation Both ends remain in parallel when excitated substrate PZT thick film and electrode structure Electrode structures d 31 actuator d 33 -mode d 31 -mode Electrode structures d 33 actuator D Ernst et al., Advances in Applied Ceramics, 114 (2015)

13 Micro-Positioning Stages for Optical Applications Experimental setup Al2O3 substrate: t = 270 µm PZT thick film: t = 115 µm SMD for voltage division and monitoring Experimental results Planar and tilt free lift Stroke 130 E = 1.66 kv/mm Micro-lens array Monitoring Voltage division

14 Micro-Positioning Stages for Optical Applications Test Setup for integration into plenoptic camera Low profile actuator t < 500 µm High overall strokes x ~ 100 µm object main lens intermediate image plane microlens array image plane Step-wise actuation: x = 20 µm, t Rise = 20 ms, t Dwell = 200 ms Standard 16 mm C- mount lens Micro-positioning stage with micro-lens array Commercial CMOS Sensor

15 Summary A system of piecoelectric, contact and dielectric thick film materials is available for screen printing PZT thick film actuators have been printed on LTCC and alumina substrates Suitability was demonstrated for two optical applications: Adaptive mirrors Micro-lens array in a plenoptic camera Piezoelectric actuators can succesfully be applied in optical systems Financial support by the German Research Foundation within the Priority Program SPP1337 Active Micro-Optics

16 Thank you for your attention! Dr. Holger Neubert Fraunhofer Institute for Ceramic Technologies and Systems Winterbergstraße 28, Dresden, Germany