Dynamic displacement measurement beyond half-wavelength in phase-modulated optical interferometer

Abstract

We demonstrate an interference signal-processing method that extends the measurement range of dynamic displacement beyond half the wavelength of light without deteriorating the measurement accuracy in a phase-modulated optical interferometer. The measurement range extension is realized by the algorithm focusing on peak direction of the interference signal waveform. Deterioration of measurement accuracy is avoided by the data processing that removes noisy data sets. Performance of the proposed system is evaluated by the experiments using a pseudo-vibrator composed of a phase modulator. In the experiments using a lead zirconate titanate (PZT) device as a sample, we successfully measure the dynamic displacement of up to 3127 nm, which is larger than the light source wavelength of 1537 nm. Proof-of-principle simulations, including the evaluation of the measurement error, are also conducted, the results of which show that the measurement error of the proposed method is small in principle.

Technical and Economic Description of the Research on a Measuring Device for Continuous Measurement of the Diameter and Vibration of the Workpiece during the Machining Process

“…e impact of the splinter is partially removed by placing the light beam transmitter with rounded upper part in the lower part of the device and, at the same time, by the fact that the receiver and transmitter are distant enough from the zone of cutting. 6), adjustable arm (7), bolt of distance setting (8), bolt of angle setting ( 9), workpiece with radius R 1 (10), workpiece with radius R 2 (11), measuring, evaluation, and display device (12).…”

“…To achieve specific continuous measurement of the workpiece diameter, we can focus on those quantities that are influenced to the greatest extent by the changing of the workpiece diameter. When selecting these quantities, the emphasis was also put on other indicators influencing the result of the measurement such as difficult construction of mechanical and electronic device necessary to provide the sensing, simplicity of the sensing principle, energy and economic efficiency of the sensing process, and sensing precision and sensitivity [9][10][11][12].…”

“…Figure 1: Optical sensor placed on tool holder. Description: transmitter of infrared light (1), receiver of infrared light (2), adjustable holder (3), console (4), turning tool (5), mounting bolt (6), adjustable arm(7), bolt of distance setting(8), bolt of angle setting (9), workpiece with radius R 1(10), workpiece with radius R 2(11), measuring, evaluation, and display device(12).…”

Real-time laser shape measurement using intensity correlation with phase modulation signal

“…The interferometric measurement is effective in many cases especially for measuring a displacement of less than the optical wavelength. In our research team, we have been studying a dynamic displacement measurement using a phase-modulated interferometer [5][6][7][8][9][10][11][12][13] , which can measure an unsteady movement of several tens of nanometers with a frequency up to 100 MHz 7 . On the other hand, incoherent methods including time-of-flight and modulation methods are useful for large displacement measurement ranging from millimeters to meters.…”

Laser displacement measurement using intensity modulation with a phase-modulated radio-frequency signal

“…The coherent-based distance or displacement measurement systems using interferometry can provide very accurate measurements within the range of laser coherence. [1][2][3][4][5][6][7][8][9][10][11] The highest performance of interferometric measurement is represented by the application to gravitational wave detection. 11) The incoherent-based measurement systems based on triangulation, [12][13][14] confocal detection, 15) time-of-flight, [16][17][18] or signal phase shift [19][20][21] can also provide high accuracy.…”