Conical Scan Piezo
Since the bandwidth of the mechanical construction of SPM´s is currently our bottle-neck for fast scanning, LPM works continuously on the development and improvement of new scanner concepts. This includes the design of the mechanical loop between the tip and the sample, as well as piezo scan elements and geometries, e.g. tubes, plates, shear elements and stacks.
One of LPM's developments is a conical piezo element. The advantage of this shape compared to a regular tube scanner is a combination of higher mechanical stiffness and a a high resonace frequence. This makes the systems less sensitive to external vibrations and improves the maximum scan speed, with an almost uncompromised scan range.
LPM is capable of delivering custom-shaped conical piezos of all dimensions. Variation of the cone-angle will affect both the scan-range and the resonance frequency. Using a finite element calculation that includes also piezo electric effects, we can calculate the expected scan range as well as the mechanical resonance frequencies.
For a conical shaped piezo, whose dimensions are comparable with those of a standard tube piezo, the scan range is still ~800 nm in the lateral (X,Y) direction and ~400 nm, in the vertical (Z) direction for scan voltages of ± 200 V. Figure 1 shows the resonance frequency curve, in which the lowest resonance frequency is given by bending modes around 45 kHz
The table below shows the properties of our standard piezo material. We also offer the possibility to fabricate conical piezos out of other piezo materials, supplied by the customer.
As an electrode layer we can apply an UHV-compatible, conductive coating which can be segmented according to user demands. The electrodes can be segmented in the standard four- quadrant configu-ration as well as in a three-electrode segmentation. The segmented piezos are fully UHV-compatible.
- d31 @ 293 K = -1.73 Å / V
- d33 @ 293 K = 3.80 Å / V
- d31 @ 4.2 K = -0.31 Å / V
- d33 @ 4.3 K = 0.69 Å / V
- Dielectric constant Kt3 = 1725
- AC depoling field = 7 kV / cm RMS
- Young's modulus = 6.3 x 1010 N / m2
- Thermal conductivity = 1.5 W / m °C
- Density = 7.5 g/cm3
- Mechanical Q-factor = 100
- Poisson's ratio = 0.31