A method for linearization of a laser interferometer down to the picometre level with a capacitive sensor

Seppä, Jeremias; Korpelainen, Virpi; Merimaa, Mikko; Picotto, Gian Bartolo; Lassila, Antti

doi:10.1088/0957-0233/22/9/094027

Cited by 16 publications

(15 citation statements)

References 20 publications

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“…In order to convert the capacitance into the displacement, we calibrate our capacitive sensor with a SIOS SP-DIS differential plane-mirror interferometer [18]. During the calibration, the moving plate is moved away from the static plate by the displacement stage for a distance of about 2.8 mm.…”

Section: B Calibration and Sensitivitymentioning

confidence: 99%

A Capacitive Sensor for the Measurement of Departure From the Vertical Movement

Zeng

Liu

et al. 2016

IEEE Trans. Instrum. Meas.

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A capacitive sensor is proposed to measure the departure from the vertical movement. It has a special structure consisting of a long silica filament static plate and a cylindrical-surface moving plate. Now it is adopted to measure the horizontal displacement of the movable coil moving along the vertical direction in a joule balance. For the consideration of avoiding the error caused by the transfer process of direction reference, the sensor is designed to have a direct vertical direction reference. The measurement errors caused by the imperfection of the capacitive sensor plates are discussed. In addition, the characteristics of the sensor, such as sensitivity, resolution, and short-time stability, have been analyzed through experiments. The experimental results show that the resolution of the sensor is better than 0.05 µm, and the short-time stability is about 0.1 µm peak to peak, which is better than that of the alcohol mirror. The combined uncertainty of the capacitive sensor obtained through analysis and experiments is 1.68 µm.Index Terms-Capacitive sensor, direct vertical direction reference, joule balance, measurement of departure from the vertical movement.

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Section: B Calibration and Sensitivitymentioning

confidence: 99%

A Capacitive Sensor for the Measurement of Departure From the Vertical Movement

Zeng

Liu

et al. 2016

IEEE Trans. Instrum. Meas.

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“…3) [6]. In this instrument light from a 633 nm HeNe heterodyne laser head (Zygo ZMI7702) is split into two measurement beams using a nonpolarizing beamsplitter.…”

Section: Traceability Into Ts By Sdhlimentioning

confidence: 99%

Sub-kHz traceable characterization of stroboscopic scanning white light interferometer

Heikkinen

Kassamakov

Paulin

et al. 2014

Optical Micro- And Nanometrology V

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Scanning white light interferometry (SWLI) is an established methodology for non-destructive testing of MEMS/NEMS. In contrast to monochromatic interference microcopy SWLI can unambiguously resolve surfaces featuring tall vertical steps. Oscillating samples can be imaged using a stroboscopic SWLI (SSWLI) equipped with a pulsed light source.To measure static samples the lateral and vertical scales of the SSWLI can be calibrated using transfer standards with calibrated dimensions such as line scales, 2D gratings, gauge blocks, and step height standards. However, traceable dynamic characterization of SSWLI requires a transfer standard (TS) providing repeatable traceable periodic movement.A TS based on a piezo-scanned flexure guided stage with capacitive feedback was designed and manufactured. The trajectories of the stage motion for different amplitude and frequency settings were characterized to have ~2 nm standard uncertainty. Characterization was made using a symmetric differential heterodyne laser interferometer (SDHLI). The TS was first used to characterize quasidynamic measurements across the vertical range of the SSWLI, 100 µm. Dynamic measurement properties of the SSWLI were then characterized using a sinusoidal vertical trajectory with 2 µm nominal amplitude and 50 Hz frequency. The motion amplitude of the TS, 2038 nm, measured with the SSWLI was 6 nm smaller than the amplitude measured with SDHLI. The repeatability of SSWLI expressed as experimental standard deviation of the mean was 8.8 nm. The maximum deviation in instantaneous displacement and oscillation velocity were 49 nm and 27 µm/s, respectively.A traceable method to characterize the capacity of the SSWLI to perform dynamic measurements at sub-kHz frequencies was demonstrated.

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“…A symmetric differential heterodyne laser interferometer (SDHLI) system 16 was used to calibrate the TS in a vertical setup, see Fig. 2.…”

Section: Laser Interferometer Measurementmentioning

confidence: 99%

“…The periodic nonlinear error (λ∕2 period) of the interferometer was suppressed to subnanometer range with an error separation technique. 16 SDHLI measures differentially the change in optical path length of the measurement and reference arms. The SDHLI measurement beam illuminated to within 1 mm, the same spot on the mirror near the edge that was used in the (S) SWLI measurements to reduce the Abbe error.…”

Section: Laser Interferometer Measurementmentioning

confidence: 99%

Quasidynamic calibration of stroboscopic scanning white light interferometer with a transfer standard

et al. 2013

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Abstract. A stroboscopic scanning white light interferometer (SSWLI) can characterize both static features and motion in micro(nano)electromechanical system devices. SSWLI measurement results should be linked to the meter definition to be comparable and unambiguous. This traceability is achieved by careful error characterization and calibration of the interferometer. The main challenge in vertical scale calibration is to have a reference device with reproducible out-of-plane movement. A piezo-scanned flexure guided stage with capacitive sensor feedback was attached to a mirror and an Invar steel holder with a reference plane-forming a transfer standard that was calibrated by laser interferometry with 2.3 nm uncertainty. The moving mirror vertical position was then measured with the SSWLI, relative to the reference plane, between successive mirror position steppings. A lightemitting diode pulsed at 100 Hz with 0.5% duty cycle synchronized to the CCD camera and a halogen light source were used. Inside the scanned 14 μm range, the measured SSWLI scale amplification coefficient error was 0.12% with 4.5 nm repeatability of the steps. For SWLI measurements using a halogen lamp, the corresponding results were 0.05% and 6.7 nm. The presented methodology should permit accurate traceable calibration of the vertical scale of any SWLI.

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A method for linearization of a laser interferometer down to the picometre level with a capacitive sensor

Cited by 16 publications

References 20 publications

A Capacitive Sensor for the Measurement of Departure From the Vertical Movement

A Capacitive Sensor for the Measurement of Departure From the Vertical Movement

Sub-kHz traceable characterization of stroboscopic scanning white light interferometer

Quasidynamic calibration of stroboscopic scanning white light interferometer with a transfer standard

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