Piezo-Actuated Adaptive Prisms for Optical Scanning

Piezo-actuated adaptive prisms for continuously adjustable bi-axial scanning

“…We have developed two optimized versions of a piezo-actuated adaptive fluid prism with an aperture of 8 mm using a suitable choice of the actuation concept, an improved design of the fluid chamber, and an FEM-based optimization of the details of the design. For the prism that was optimized for large tilt angles, we found maximum surface tilt angles of ± 12.3 • (± 6.1 • scan angle) with 75% response times of less than 2.5 ms compared to our previously published design with approximately ±2.6 • tilt angle and response times of 59 ms [21] or an electrowetting prism in the literature with scanning angles of ±6.4 • (discrete steps in the second dimension) and response times in the range of 400 ms [19]. Modern galvanometer scanner can achieve response times in the range of approximately 0.5 ms for a scanning range of 4 • [10], which was approximately the same angular range as measured in our step response measurement, i.e.…”

“…To define the bi-axial tilt angle of the top glass, we used three active beams. In figure 4, we show our initial mechanical design of [21] with the most important geometric dimensions in a full device overview (left) and a cross-section through the prism (right). Furthermore, we marked critical structures that restrict the deflection angle of the prism (circles).…”

“…In [21], we demonstrated a first prototype of a piezoactuated fluidic prism with two glass-fluid interfaces and the ability for bi-axial scanning. With an aperture of 8 mm it offers scan angles of approximately ±1.3 • and a response time of 59 ms [21], which is faster than the mentioned electrowetting prisms.…”

“…In [21], we demonstrated a first prototype of a piezoactuated fluidic prism with two glass-fluid interfaces and the ability for bi-axial scanning. With an aperture of 8 mm it offers scan angles of approximately ±1.3 • and a response time of 59 ms [21], which is faster than the mentioned electrowetting prisms. Furthermore, the stiff glass provides a good optical surface with potentially small wavefront errors and it also allows for a quite flexible choice of the optical fluid to introduce phase shifts by changing the optical path in the fluid.…”

Micro Fresnel mirror array with individual mirror control

“…Typically, only negative mirror angles are required for the application, which reduces the deflection range of the mirrors in the symmetric case by 50%. To overcome this problem, a pre-deflection can be defined by depolarizing the upper piezo sheet before gluing and finally re-polarizing the piezo material by applying an electric field higher than the coercive field strength of the material [19,20]. This creates a remanent strain in the piezo bimorphs which induces a pre-deflection of the mirrors in the negative direction.…”