This paper reports on the thermo-mechanical modeling and characterization of a screen printed deformable mirror. The
unimorph mirror offers a ceramic LTCC substrate with screen printed PZT layers on its rear surface and a machined
copper layer on its front surface. We present the thermo-mechanical model of the deformable mirror based on Ansys
multiphysics. The developed mirror design is practically characterized. The homogeneous loading of the optimized
design results in a membrane deformation with a rate of -0.2 μm/K, while a laser loading causes a change with a rate of
1.3 μm/W. The proposed mirror design is also suitable to pre-compensate laser generated mirror deformations by
homogeneous thermal loading (heating). We experimentally show that a 35 K pre-heating of the mirror assembly could
compensate an absorbed laser power of 1.25 W.
The miniaturization of actuators results in two major consequences: First, the reduction in efficiency depending on the
physical principle. Second, the increasing requirements in positioning accuracy during the assembly and fabrication
process in combination with low cost production.
Electrostatic polymeric actuators providing out-of-plane motion which can be completely fabricated in parallel
fabrication steps and hence be produced on wafer level are compliant to these tolerance and cost constraints.
The electrostatic actuation principle is a surface effect and therefore independent of the volume. In addition, the
efficiency of electrostatic actuation increases with a decreasing gap size between the electrodes. The simple morphology
of such actuators can be easily produced by UV-replication of polymeric materials. In consequence, the electrostatic
actuation principle is predestined for the combination with low cost wafer level fabrication.
This paper reports on the first results of successfully fabricated electrostatic actuators produced on wafer level. Instead of
using a standard silicon substrate our approach is based on the lithographic structuring of the non-conducting material
ORMOCER®. In comparison ORMOCER® has a significantly lower elastic modulus (about 1 GPa). Therefore, only a
fraction of actuation voltage is necessary for a similar deflection. The material is structured using photolithography and
the electrodes are realized with coatings of thin metal layers. Experimental results show a deflection up to 49,1 μm at
500 V for an 75 μm thick cantilever beam fixed at both ends. Good agreement between measurements and simulations is
achieved, proving the applicability of the software and the assumed material parameters.
This paper reports on new results of the development of a unimorph laser beam shaping mirror based on Low
Temperature Cofired Ceramics (LTCC). The deformable mirror is actuated by a side screen printed piezoceramic thick
film based on lead zirconate titanate (PZT). The reflective surface is electroplated copper that is diamond machined to
flatten the surface. We introduce the solder jet bumbing fixation technology to mount the deformable mirror into a
metallic mounting. This assembling technology introduces very little energy input and thus also very little deformation
into the mirror. The material of the mounting is CE7 that is especially thermal adapted to the deformable mirror. We will
present results on deflection and resonance frequency for two different mirror designs.
This paper reports on a novel construction of a deformable mirror for laser beam shaping. The deformable mirror is
actuated by screen-printed thick film piezoceramic unimorphs based on lead zirconate titanate (PZT). Different actuator
layouts are realized and will be presented. We use Low Temperature Cofired Ceramics (LTCC) as a substrate material
with a metallization as reflective surface. LTCC offers easy integration of holding structures. The reflective mirror
surface is electroplated copper. After deposition, the copper layer is diamond machined to achieve excellent optical
surface quality <10 nm (rms). We build deformable mirrors with 1, 13 and 19 actuators and a total stroke of more than
20 μm and characterize them with a wave front sensor.
A PZT thick-film is printed on an Al2O3-Substrate, generating a cantilever monomorph. A task of positioning with two
degrees of freedom is successfully fulfilled. It is realized by two parallel arranged cantilevers that are mechanically
combined with a bar with solid hinges. The solid hinges allow flexibility for different amounts of bending of the two
cantilevers, while the bar permits a stiff support for a lens. As the bar underlies very small torsion there is no stress
induced change in the index of refraction of the lens. Different combinations of hinges are simulated and practically
tested. In the presented work, a lens is successfully positioned in front of a laser diode. The loss of the coupling
efficiency due to the shrinking of the adhesive joint can be scaled down. The paper presents the theoretical work
including the report on analytic and FEM simulation of both deflection and stress. The practical validation is also
presented. A simple sensor system is used to find an optimized position of the lens in front of the diode. This position is
automatically held over a long period of time. With the fabrication of the actuator using thick-film printing and laser
cutting a low cost device is built.
The generation of high energy femtosecond pulses in Optical Parametric Amplifier (OPA) pumped by fiber laser at a repetition rate of 1MHz is reported. Highly nonlinear fibers are used to create an intrinsically synchronized signal for the parametric amplifier. Seeding the OPA by a supercontinuum generated in a photonic crystal fiber, large tunability extending from 700 nm to 1500 nm of femtosecond pulses is demonstrated, with pulse energies as high as 1.2 μJ. Generating the seed using only SPM in a standard fiber, broadband amplification over more than 85 nm and subsequent compression down to 46 fs in a prism sequence are achieved. Pulse peak powers pulses above 10 MW together with 0.5 W of average power is achieved. This system appears to be very interesting due to scalability of pulse energy and average power of both involved concepts: fiber laser and parametric amplifier.