Key Features

For high precision contactless measurement of displacements, SmarAct provides the PICOSCALE interferometer that offers the following key features:

  • 3 parallel laser interferometers for 3D measurements in one instrument
  • Measurement bandwidth up to 2.5 MHz (10 MHz sample rate) with a resolution down to 1 pm1
  • Measurements possible on most materials (plastic, glass, metal and even water)
  • Wide range of sensor heads available for different applications and environments (including vacuum and cryogenics)
  • Extendable to a complete laboratory measurement and control instrument with optional modules
  • Proven performance with 100s of satisfied customers


1 When analysing periodic displacements in the frequency domain

Working Principle

All PICOSCALE products are based on a Michelson interferometer, a precise method to measure displacements and vibrations. The Michelson interferometer consists of a wavelength-stabilized laser, a beam splitter, a target and a reference mirror. At the beam splitter, the light from the laser is divided into two arms. One arm is directed to the target surface while the other is directed to the reference mirror. After the light of both arms is reflected by the target surface and reference mirror, respectively, it travels back to the beam splitter. Here, both arms recombine and interference takes place. The interference signal contains information on the displacement of the target surface with respect to the reference mirror.

Schematic setup of a sensor head



PICOSCALE Interferometer
Resolution [pm] 1
Repeatability [nm] 1

Accuracy [nm]

Accuracy (length proportional)



RMS Noise [pm] 70*
Amplitude Spectral Density [pm] 1 @ 1000 Hz
Long Term Stability [nm} 1*
Maximum Target Velocity [m/s] 2
Target Reflectivity 4% - 100%
Maximum Working Distance [mm] 1000
Absolute Position Estimation 1% of working distance

*Working distance 20 mm, ambient conditions, measurement bandwidth 1.2 kHz



Advantages of Michelson Interferometers

Michelson Interferometers have several advantages in terms of displacements sensing accuracy and flexibility.

Learn more in this article: Advantages of Michelson interferometers compared to other architectures