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PicoScan Vibrometer

The PICOSCAN Vibrometer addresses the need for R&D and QC instrumentation that keeps pace with the ever increasing complexity of micromechanical systems. SmarAct’s vibrometer is developed for megapixel imaging of vibrational modes of microscopic structures. This is achieved by raster-scanning a tightly focussed laser beam of a Michelson interferometer over the sample to measure the vibrations for each pixel of the microscopic image. The PICOSCAN Vibrometer is equipped with a piezo-based sample shaker and a digital lock-in amplifier to measure amplitude and phase of the vibrations from which bending modes of up to 2.5 MHz can be reconstructed.

Unique features

  • The interferometer laser beam is used simultaneously to record a confocal reflection image of the sample, which is intrinsically aligned with vibration measurements. Thus an additional microscope imaging system is not required.
  • Even though the controller and UHV-compatible scanner are kept very compact, it provides structure scans with a size of 20 mm.

System components

  • PICOSCAN Vibrometer: contains an interferometer, function generator and lock-in amplifer (33 cm x 28 cm x 7.5 cm)
  • PICOSCAN Motion Controller: performs the closed loop operation of the XYZ positioners and contains a power amplifer for the shaker stage (33 cm x 28 cm x 7.5 cm)
  • XYZ scanner (10 cm x 5.5 cm x 7.5 cm) to raster-scan the focussing laser head over the sample
  • Granite plate (20 cm x 15 cm x 4 cm) with 2.5 cm diameter post for mounting the scanner
  • Shaker stage with holder

 

Vibration measurement
Working principle: Michelson interferometer, single mode fibre coupled
Measurements laser: 1550 nm DFB laser diode, stabilized (NIST traceable), Power output < 1 mW (Laser class 1)
Laser spot diameter at focus: 7 µm
Resolution: sub-pm for single point measurements, 0.1 nm in imaging mode
Imaging mode: Amplitude and phase images can be analyzed with the included software or exported
Single point mode: FFT spectrum from 1 Hz - 2.5 MHz with max. 2.5 million points
Digital lock-in amplifier
Frequency range: 500 Hz - 2.5 MHz
Reference signal: Available through standard shaker stage and as output signal to drive custom actuators
Time constant: Adjustable from 1 µs to 0.5 ms
Dynamic reserve: >100 dB
Optical microscope
Working principle: Confocal laser scanning using the interferometer's measurement laser
Focus adjustment: Manual or automatic with closed loop piezo drive
Lateral resolution: 5 µm
Min. pixel size: 1 µm
Max. image size: 20 x 20 mm
Max. number of pixels: 1000 x 1000
Scanning motion system
Working principle: 3 axes linear piezo drive, closed loop
Resolution: 1 nm
Repeatability: 30 nm
Max. travel: 20 mm (others on request)
Dimensions
Controller: 2 units of each 33.0 x 27.0 x 7.0 cm (W x L x H)
Scanner mount: Granite stone 15.0 x 20.0 x 4.0 cm (W x L x H) with stainless steel post 2.5 x 15.0 cm (d x H)
Scanning stage: 5.5 x 11.0 x 7.5 cm (W x L x H)
Shaker stage: Stainless steel 8.0 x 1.5 cm (d x H)

Application Notes

We have created several application notes in which various measurements are described in more detail:
Application Notes overview

Reconstruction examples

Bending modes of a loud speaker at different frequencies:

 

PicoScan Vibrometer

 

PicoScan Vibrometer

 

PicoScan Vibrometer