In this work, we evaluate the measurement noise of a commercial point autofocus surface topography measuring instrument. This metrological characteristic was determined using a calibrated optical flat following methodologies described in good practice guidelines and draft ISO specification standards, using the averaging and subtraction methods. The static noise of the instrument was investigated by examining the repeatability of the vertical Z-axis. The autofocus sensor repeatability was assessed by measuring its vertical positioning deviation, whilst focused on an optical flat, but without scanning laterally. During the investigation, the instrument proved to be sensitive to environmental temperature disturbance, which introduced a significant distortion in the measured topography and resulted in relatively high measurement noise. The spatial frequency of the distortion in the topography was found to be consistent with the frequency of temperature fluctuation in the measurement chamber. Similarly, static noise and autofocus sensor repeatability were affected by temperature fluctuation. However, after applying the built-in drift correction routine in the instrument software during measurement, the effect of temperature fluctuation was significantly reduced from a measurement noise of 20 nm to 2 nm, with a sampling frequency of 30.6 Hz. In this paper, we specify measurement noise along with the corresponding measurement bandwidth.
Measurement noise evaluation, noise bandwidth specification and temperature effects in 3D point autofocusing microscopy / Maculotti, Giacomo; Feng, Xiaobing; Galetto, Maurizio; Leach, Richard. - ELETTRONICO. - (2018), pp. 155-156. (Intervento presentato al convegno 18th international conference of the european society for precision engineering and nanotechnology tenutosi a Venezia (ITA) nel 4-8 June 2018).
Measurement noise evaluation, noise bandwidth specification and temperature effects in 3D point autofocusing microscopy
Giacomo Maculotti;Maurizio Galetto;
2018
Abstract
In this work, we evaluate the measurement noise of a commercial point autofocus surface topography measuring instrument. This metrological characteristic was determined using a calibrated optical flat following methodologies described in good practice guidelines and draft ISO specification standards, using the averaging and subtraction methods. The static noise of the instrument was investigated by examining the repeatability of the vertical Z-axis. The autofocus sensor repeatability was assessed by measuring its vertical positioning deviation, whilst focused on an optical flat, but without scanning laterally. During the investigation, the instrument proved to be sensitive to environmental temperature disturbance, which introduced a significant distortion in the measured topography and resulted in relatively high measurement noise. The spatial frequency of the distortion in the topography was found to be consistent with the frequency of temperature fluctuation in the measurement chamber. Similarly, static noise and autofocus sensor repeatability were affected by temperature fluctuation. However, after applying the built-in drift correction routine in the instrument software during measurement, the effect of temperature fluctuation was significantly reduced from a measurement noise of 20 nm to 2 nm, with a sampling frequency of 30.6 Hz. In this paper, we specify measurement noise along with the corresponding measurement bandwidth.File | Dimensione | Formato | |
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https://hdl.handle.net/11583/2712331
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