3.9 KiB
+++ title = "Interferometers" author = ["Thomas Dehaeze"] draft = false +++
- Tags
- [Position Sensors]({{< relref "position_sensors" >}})
Manufacturers
| Manufacturers | Links | Country |
|---|---|---|
| Attocube | link | Germany |
| Zygo | link | USA |
| Smaract | link | Germany |
| Qutools | link | Germany |
| Renishaw | link | UK |
| Sios | link | Germany |
| Keysight | link | USA |
| Optics11 | link | Netherlands |
Environmental Units
| Temperature (\(\pm\ ^oC\)) | Pressure (\(\pm\ hPa\)) | Humidity \(\pm\% RH\) | Wavelength Accuracy (\(\pm\ \text{ppm}\)) | |
|---|---|---|---|---|
| Attocube | 0.1 | 1 | 2 | 0.5 |
| Renishaw | 0.2 | 1 | 6 | 1 |
| Picoscale | 0.2 | 2 | 2 | 1 |
Interferometer Precision
{{< figure src="/ox-hugo/position_sensor_interferometer_precision.png" caption="Figure 1: Expected precision of interferometer as a function of measured distance" >}}
Sources of uncertainty
Sources of error in laser interferometry are well described in (Ducourtieux 2018).
It includes:
- Laser Source Stability
- Variation of refractive index of air, which is dependent of:
- Temperature: \(K_T \approx 1 ppmK^{-1}\)
- Pressure: \(K_P \approx 0.27 ppm hPa^{-1}\)
- Humidity: \(K_{HR} \approx 0.01 ppm % RH^{-1}\)
- These errors can partially be compensated using an environmental unit.
- Air turbulence (Figure 2)
- Non linearity
{{< figure src="/ox-hugo/interferometers_air_turbulence.png" caption="Figure 2: Effect of air turbulences on measurement stability" >}}
Bibliography
Ducourtieux, Sebastien. 2018. “Toward High Precision Position Control Using Laser Interferometry: Main Sources of Error.” https://doi.org/10.13140/rg.2.2.21044.35205.
Jang, Yoon-Soo, and Seung-Woo Kim. 2017. “Compensation of the Refractive Index of Air in Laser Interferometer for Distance Measurement: A Review.” International Journal of Precision Engineering and Manufacturing 18 (12):1881–90. https://doi.org/10.1007/s12541-017-0217-y.