Do you have any questions for SIOS customer service? Below is a collection of frequently asked questions and the appropriate answers. If you cannot find what you are looking for here, please use our support form.
He-Ne-lasers are the traditional laser sources for precision interferometry. In interferometry the laser wavelength is the measurement reference. The wavelength of a SIOS He-Ne laser is traceable to an international standard and is calibrated against a Iodine stabilized He-Ne laser. This certified traceablity to a national calibration standard is essential in the application of laser interferomety for use as a calibration tool.
Furthermore, the SIOS He-Ne lasers have good wavelength stability with nearly no aging effects. At the moment, in the visible light range, similar traceablity and aging stability cannot be reached with laser diodes.
Regarding the international laser saferty standard DIN EN 60825-1, the SIOS interferometer is classified in the laser safety class 2M. The automatic reflex of the eye to close with exposure to bright light sources provides sufficient protection in this classification so special safety glasses are not normaly required.
An exception is the laser-interferometric gauging probe of LM-series with laser safety class 1, because the laser radiation does not penetrate to the outside here.
The stand-alone lasers SL02/SL03/SL04 (available without the interferometer and only as a laser light source) have slightly higher optical power and belong to the laser safety class 3R. A direct view with the eye into the laser beam may be dangerous, so special laser protection glasses for 632nm are required; other precautions may also be required (mechanical interlocks).
For more information contact your national standard agency.
The light from the He-Ne-laser is fed to the sensor head via a special optical fiber. This has the following main advantages:
The sensor head can be constructed from aluminum (standard), stainless steel and invar. For normal calibration applications aluminum is preferred because long term stability (> hours) doesn’t play a key role in most applications. Aluminum is also lightweight, making the sensor easier to mount.
For measurements where long term stability is very important or for integration of the sensor head into machine assemblies, the thermal expansion coefficient of the sensor material should match the base material to avoid stresses due to different mechanical expansion. Sensor heads constructed in stainless steel match steel and granite assemblies. Sensor heads made of invar match best to Zerodur, ceramics and quartz assemblies. For more details please contact SIOS.
The following interfaces are available:
The USB interface is available in nearly all devices as a standard. The other interfaces may be ordered as optional components.
We offer the following standard software for our interferometers or vibrometers:
Some tasks require the creation of application specific software. We have a huge library of typical solutions and extensive experiences in measurement applications. So we are able to offer customer specific software at competitive rates. Please contact SIOS for more details.
Yes. You can access the USB- and RS232-interfaces. We offer a comprehensive software support:
The interferometer controller has trigger inputs for triggering the measurement of single values and to trigger the start of a measurement. It enables the synchronization with other measurement equipment with a common TTL type pulse. The trigger has low latency to external events like activations of index switches and incremental encoder pulses.
Optional: A trigger generator card is available which can produce a software controlled common trigger pulse for synchronize different measurement devices.
Calibrations of SIOS interferometers at the German national institute PTB have shown mean systematic deviations in the range around 0.12 ppm which is equivalent to 120nm/m.
The measurement accuracy of a laser interferometer in air is mainly influenced by the determination of the air refraction along the laser beam. To determine the air refraction environmental parameters like temperature, air pressure and humidity are measured with high precision.
In practice the limiting factor is the assembly in which the interferometer is integrated into, because it must guarantee a sufficient stability (thermally and vibrationally) and allow representative measurements of the environmental parameters to be measured. Please ask us for more support.
Independently from the measurement accuracy, the measurement resolution of the signal processing is around 5 pm. This resolution is particulary visible in ultra stable assemblies (especially, for example, in vacuum) and with vibrometry.
Yes. Traceable measurements are essential for calibration applications and our interferometers are developed with the prerequisite to facilitate traceable measurements.
For the calibration of our laser interferometers the responsibility of national standards institutes and a list of related offers can be found on the website of the BIPM. In Germany the PTB in Braunschweig makes these calibrations for SIOS.
As an alternative to a calibration of the whole interferometer at a national institute, SIOS can provide separate test reports or DAKKS calibrations for laser frequency and environmental sensors (temperature, air pressure, humidity).
SIOS has extensive experiences with measurements in vacuum. Implementing a sensor head in vacuum, requires special materials for sensor head, cables, connectors and vacuum feed throughs. Vacuum compatible systems are available on request. Please specify your application and the specification of the vacuum in mbar.
Maintenance activities are to be carried out after a maintenance period by trained specialists from SIOS. We recommend a maintenance interval of one year depending on the application. For regular maintenance, we recommend taking out a maintenance contract.
Need help as soon as possible? Please use our contact form for support requests.
You are welcome to send us your support requests directly to
Please do not forget to send your data, such as name, address, serial number of the system or a photo. You don't need a RMA number to send your device to us, as soon as we receive the system, the RMA number will be assigned automatically and communicated to you. After a thorough examination of the product, you will immediately receive a non-binding repair offer.