Research on long-range grating interferometry with nanometer resolution

Chu, Xingchun; Lu, Hongbo; Zhao, Shanghong

doi:10.1088/0957-0233/19/1/017001

Cited by 26 publications

(10 citation statements)

References 13 publications

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“…A measurement with a grating uses Moiré fringes formed by superimposing periodic grid lines between a scale grating and index grating. Because its measurement datum is based on the period of the grating scale [8], a grating with smaller pitch provides higher measurement accuracy. Nowadays, many researchers have proposed many lithography methods to reduce the grating period, such as multiple nanoimprint lithography [9], pressed self-perfection by liquefaction [10], and negative electron-beam lithography [11].…”

Section: Introductionmentioning

confidence: 99%

A High Precision Time Grating Displacement Sensor Based on Temporal and Spatial Modulation of Light-Field

Zhu

et al. 2020

Sensors

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A new displacement sensor with light-field modulation, named as time grating, was proposed in this study. The purpose of this study was to reduce the reliance on high-precision measurements on high-precision manufacturing. The proposed sensor uses a light source to produce an alternative light-field simultaneously for four groups of sinusoidal light transmission surfaces. Using the four orthogonally alternative light-fields as the carrier to synthesize a traveling wave signal which makes the object movement in the spatial proportion to the signal phase shift in the time, the moving displacement of the object can be measured by counting time pulses. The influence of the light-field distribution on sensor measurement error was analyzed in detail. Aimed to reduce these influences, an optimization method that used continuous cosinusoidal light transmission surfaces with spatially symmetrical distribution was proposed, and the effectiveness of this method was verified with simulations and experiments. Experimental results demonstrated that the measurement accuracy reached 0.64 µm, within the range of 500 mm, with 0.6 mm pitch. Therefore, the light-field time grating can achieve high precision measurement with a low cost and submillimeter period sensing unit.

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Section: Introductionmentioning

confidence: 99%

A High Precision Time Grating Displacement Sensor Based on Temporal and Spatial Modulation of Light-Field

Zhu

et al. 2020

Sensors

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“…The encoder can be either incremental or absolute. With the prominent advantages of especially high accuracy, stability to environmental factors, a long measurement range and so on, it has been applied in high-technology manufacturing, such as in ultra-precision machine assembly, semiconductor manufacturing, and nano-scale sensing [1][2][3]. Since noncontact incremental linear encoders following interpolation can provide resolutions as fine as several picometers with the lowest measurement hysteresis, they are the optimal choice for high-accuracy position measurement [4].…”

Section: Introductionmentioning

confidence: 99%

Calibration of non-contact incremental linear encoders using a macro–micro dual-drive high-precision comparator

et al. 2015

Meas. Sci. Technol.

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The accuracy of a linear encoder is determined by encoder-specific errors, which consist of both long-range and cyclic errors. Generally, it is difficult to measure the two errors of a non-contact incremental linear encoder with a large measuring range and small signal period in one measurement because of the contradiction between long travel range and high resolution. To resolve this issue, a prototype high-precision interferometric comparator with a macro–micro dual-drive system is presented. The measurement and motion resolution of the comparator are 1 nm and 3 nm, respectively. A measuring range of 320 mm is realized and the theoretical maximum range of the comparator is 2 m. The comparator mainly includes a high-accuracy aerostatic linear-motion stage, a constant displacement ratio piezoelectric-driven stage, two laser interferometers, a 6-DOF grating pair position adjustment devices and a PC-based data processor. The measurable linear movement is afforded, respectively, by the long-stroke stage and the piezoelectric-driven stage for the long-range error and cyclic error measurement. The movement can be measured by the encoder and then be calibrated by the corresponding laser interferometer. In the experiment, the accuracy of a non-contact incremental linear encoder with a 20 μm-long signal period and 320 mm measuring range proposed by our team was calibrated after proper mounting. The long-range error is measured to be 3.123 μm, and the cyclic error is within ±0.159 μm, which matches well with the theoretical estimation given by ±0.145 μm. The measurement uncertainties are estimated and the results confirm the effectiveness and feasibility of the proposed scheme and instruments.

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“…Precise displacement measurement is of prime importance in the precision engineering and nanotechnology fields such as the semiconductor industry, MEMS manufacturing techniques, nano-lithography and nano-sensing techniques [1][2][3][4][5]. Optical encoders and laser interferometers are popular displacement measuring sensors today.…”

Section: Introductionmentioning

confidence: 99%

Design of a precise and robust linearized converter for optical encoders using a ratiometric technique

Fan

et al. 2014

Meas. Sci. Technol.

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A linearization method with improved robustness for determining the displacement from sine and cosine signals generated by optical encoders is presented. The proposed scheme is based on a ratiometric technique and a dedicated compensation method. The scheme converts the sinusoidal signals into a nearly perfectly linear output signal, from which the displacement is determined precisely using a simple linear equation. Under the condition of ideal input signals, the theoretical analysis shows that the converter enables a determination of the displacement with a non-linearity error below 0.0029 µm for a linear optical encoder with a period of 20 µm. The performance of the converter with non-ideal input signals is also evaluated by establishing the relationship between the positioning errors and the parameter deviations of the input signals. Due to the robustness of the converter against the signal amplitude imbalance, a signal processing circuit is developed to convert the signal phase-shift error into the signal amplitude imbalance error. A displacement measurement experiment was carried out by applying the converter to a linear optical encoder with a period of 20 µm. A positioning accuracy of 0.2 µm over a travel length of 80 mm was achieved under laboratory conditions. The feasibility of the proposed converter has been confirmed from the experimental results.

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Research on long-range grating interferometry with nanometer resolution

Cited by 26 publications

References 13 publications

A High Precision Time Grating Displacement Sensor Based on Temporal and Spatial Modulation of Light-Field

A High Precision Time Grating Displacement Sensor Based on Temporal and Spatial Modulation of Light-Field

Calibration of non-contact incremental linear encoders using a macro–micro dual-drive high-precision comparator

Design of a precise and robust linearized converter for optical encoders using a ratiometric technique

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