73 lines
3.9 KiB
Markdown
73 lines
3.9 KiB
Markdown
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title = "Interferometers"
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author = ["Thomas Dehaeze"]
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draft = false
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Tags
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: [Position Sensors]({{< relref "position_sensors" >}})
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## Manufacturers {#manufacturers}
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| Manufacturers | Links | Country |
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|---------------|----------------------------------------------------------------------------------------------------------|-------------|
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| Attocube | [link](http://www.attocube.com/) | Germany |
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| Zygo | [link](https://www.zygo.com/?/met/markets/stageposition/zmi/) | USA |
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| Smaract | [link](https://www.smaract.com/interferometry) | Germany |
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| Qutools | [link](https://www.qutools.com/qudis/) | Germany |
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| Renishaw | [link](https://www.renishaw.com/en/fibre-optic-laser-encoder-products--6594) | UK |
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| Sios | [link](https://sios-de.com/products/length-measurement/laser-interferometer/) | Germany |
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| Keysight | [link](https://www.keysight.com/en/pc-1000000393%3Aepsg%3Apgr/laser-heads?nid=-536900395.0&cc=FR&lc=fre) | USA |
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| Optics11 | [link](https://optics11.com/) | Netherlands |
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## Environmental Units {#environmental-units}
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<div class="table-caption">
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<span class="table-number">Table 1</span>:
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Characteristics of Environmental Units
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</div>
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| | Temperature (\\(\pm\ ^oC\\)) | Pressure (\\(\pm\ hPa\\)) | Humidity \\(\pm\\% RH\\) | Wavelength Accuracy (\\(\pm\ \text{ppm}\\)) |
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|-----------|------------------------------|---------------------------|--------------------------|---------------------------------------------|
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| Attocube | 0.1 | 1 | 2 | 0.5 |
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| Renishaw | 0.2 | 1 | 6 | 1 |
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| Picoscale | 0.2 | 2 | 2 | 1 |
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## Interferometer Precision {#interferometer-precision}
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([Jang and Kim 2017](#org95c0093))
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<a id="org69d5980"></a>
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{{< figure src="/ox-hugo/position_sensor_interferometer_precision.png" caption="Figure 1: Expected precision of interferometer as a function of measured distance" >}}
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## Sources of uncertainty {#sources-of-uncertainty}
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Sources of error in laser interferometry are well described in ([Ducourtieux 2018](#orgd56bef1)).
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It includes:
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- Laser Source Stability
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- Variation of refractive index of air, which is dependent of:
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- Temperature: \\(K\_T \approx 1 ppmK^{-1}\\)
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- Pressure: \\(K\_P \approx 0.27 ppm hPa^{-1}\\)
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- Humidity: \\(K\_{HR} \approx 0.01 ppm \% RH^{-1}\\)
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- These errors can partially be compensated using an environmental unit.
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- Air turbulence (Figure [2](#org0f5db6f))
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- Non linearity
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<a id="org0f5db6f"></a>
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{{< figure src="/ox-hugo/interferometers_air_turbulence.png" caption="Figure 2: Effect of air turbulences on measurement stability" >}}
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## Bibliography {#bibliography}
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<a id="orgd56bef1"></a>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>.
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<a id="org95c0093"></a>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>.
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