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Differential Laser Interferometer

SP 5000 DI

Highly stable differential laser interferometer with two parallel measuring beams

differential length or angle measurement of highest accuracy

minimization of environmental influences through differential measurement

thermally long-term stable sensor, temperature sensitivity < 20 nm/K

various optical reflectors can be used, e.g. spherical, plane mirror reflector

large tilt invariance of the measuring reflector

sensor head design in stainless steel as standard

beam distance: 21 mm

extensive trigger options

open interfaces for OEM software under Windows and Linux

Our ultra-stable differential laser interferometer SP 5000 DI is characterized by a unique thermal stability and is therefore preferred for long-term measurements in research and development, e.g. for the analysis of material properties.
In contrast to the standard interferometer, in the differential version the reference beam is led out of the sensor head and runs parallel to the measuring beam. This concept allows the sensor to be placed at a greater distance from the actual measurement location without significantly affecting the resolution or stability of the measurement. The length resolution of this interferometer is in the sub-nanometer range and, due to the differential principle, can be achieved at comparable measurement or beam lengths even under normal laboratory conditions.
The measurement range for the length measurement can be several meters if tilt invariant reflectors are used for the measurements. The interferometric measuring system has a modular design and can thus be adapted to the respective measuring task.
Adjustment is simple and, in particular, can be realized with long-term stability. The extension to an interferometric multi-axis system based on the SP 5000 DI interferometer allows simultaneous multi-coordinate measurements.

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Technical data

2 m
with plan-mirror
5 m
with reflector

0.1 µm/m

5 pm

±1.5 arcmin
with plane-mirror
with reflector

0.001 arcsec

Areas of application

The differential laser interferometer is available as an OEM version for installation as an encoder in machine axes. For measurements in vacuum, the SP 5000 DI is available as a vacuum-optimized version.

The standard beam distance is 21 mm. We offer other beam distances on request.

Read application example

Ideal for

long-term measurements


science / research

OEM applications

highest stability requirements

Measuring principle of the differential interferometer


Ball reflector Ø15 mm

aluminum case

with integrated magnets and screw-on

item number A033351

Ball reflector unit

beam distance 21 mm

item number A038783

Environmental Correction

sensor box SB-22

temperature transducer TT-01 for air or material temperature sensor

air humidity sensor

You would like to know
whether the differential interferometer – SP 5000 DI is the right solution for your measurement tasks?

Our SIOS experts will be happy to visit you on site. Together we can find a quick solution for your application and carry out the first test measurements in your environment.

Contact now

Related software


Software for data acquisition and visualization

Universal software for all SIOS interferometers

Basic functions for data acquisition

Synchronization settings


Software for vibration measurement

FFT analysis

Data filtering

Spectra averaging

Script control

Your contact

Falko Seyfferth

Application Engineer

+49 (0) 3677 64 47-49

Are you interested in the SP 5000 DI?

We will be happy to make you a suitable offer.

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