High-resolution Heterodyne Interferometer Research Articles

Matrix data analysis methods for applications in laser beam position measurement modules

This paper addresses the problem of selecting an optimal algorithm suitable for real-time processing of matrix sensor data in laser beam positioning applications. We compare four different algorithms and prove that the chosen one provides the same results in time by several orders of magnitude lower and with negligible memory consumption, making it suitable for use in microcontroller-based sensing modules. Full Text: PDF ReferencesS. Donati, Electro-Optical Instrumentation-Sensing and Measuring with Lasers (Prentice Hall, Upper Saddle River, NJ, 2004). DirectLink K.N. Joo, J.D. Ellis, E.S. Buice, J.W. Spronck, R.H. Munning Schmidt, "High resolution heterodyne interferometer without detectable periodic nonlinearity", Optics Expr. 18(2), 1159 (2010). CrossRef G. Budzyń, J. Rzepka, "Study on Noises Influencing the Accuracy of CNC Machine Straightness Measurements Methods Based on Beam Position Detection", J. Machine Engin. 20(3), 76 (2020). CrossRef Reference materials for PSD and CMOS sensors, , referenced 7-11-2022 CrossRef S. Das, A. Saha, "Laser Beam Position-Dependent PSD-Based Calibrated Self-Vibration Compensated Noncontact Vibration Measurement System", IEEE Trans. Instr. Meas. 68(9), 3308 (2019). CrossRef P. Zhang, J. Liu, H. Yang, L. Yu, "Position Measurement of Laser Center by Using 2-D PSD and Fixed-Axis Rotating Device", IEEE Access 7, 140319 (2019). CrossRef J. Rzepka, G. Budzyn, "Laser measurement system for machine tools", Proc. SPIE 5144, 840 (2003). CrossRef S. Xiang, H. Li, M. Deng et al., "Geometric error identification and compensation for non-orthogonal five-axis machine tools", Int. J. Adv. Manuf. Technol. 96, 2915 (2018). CrossRef N. Hagen, E. Dereniak, "Gaussian profile estimation in two dimensions", App. Opt. 47(36), 6842 (2008). CrossRef S.M. Ross, Introduction to Probability and Statistics for Engineers and Scientists (Academic Press 2014). CrossRef

High-speed high-resolution heterodyne interferometer using a laser with low beat frequency.

A high-speed high-resolution heterodyne interferometer using a laser with low beat frequency is developed. The interferometer has two spatially separated parallel beams with different frequencies. Two interference signals with opposite Doppler shift are optically generated by the interferometric optics. The measurement electronics uses two identical phasemeters for the two opposite interference signals. The two interference signals are selectively used according to the speed of the target, which makes sure that the Doppler shift of the selected signal is always positive, so that the measurable speed is no longer limited by the beat frequency of the laser source. Experimental results show that the measurement resolution is 0.62nm. The measurable speed can exceed the restriction determined by the beat frequency. Compared with a commercial interferometer, the displacement difference is less than 40nm in a travel range of 900mm.

High resolution heterodyne interferometer based on time-to-digital converter

A new heterodyne interferometer is presented, which adopts time-to-digital converter (TDC) measuring the time intervals of zero crossings of heterodyne signal for phase demodulation. Thanks to the 0.1 ns time resolution of TDC and linear phase demodulation, it can achieve high resolution and avoids nonlinear measuring distortion in other indirect high precise phase demodulation methods, such as pulse width modulation (PWM) and in-phase∕quadrature (I∕Q) method.

Performance and testing of a four channel high-resolution heterodyne interferometer

When studying complex vibrations, simultaneous measurements at several points are indispensable if one is dealing with objects whose vibrational behavior is not guaranteed to be stable over longer periods of time, such as biological specimens, micro-mechanical elements or objects characterized by nearly resonant normal modes with different vibrational patterns. Obviously, both amplitude and phase need to be measured at each point to obtain a full characterization of the vibration. We introduce birefringent beam displacers as a highly efficient beam multiplying method to create a system of four heterodyne interferometers operating in parallel from a single laser source. The design and the performance characteristics (resolution, cross-talk) of the instrument will be discussed. The system revealed the existence of running vibrational modes on an electrically driven plate clamped along its outer edge.

Two-longitudinal-mode He-Ne laser for heterodyne interferometers to measure displacement.

We propose a new configuration for a high-resolution heterodyne interferometer that employs a two-longitudinal-mode He-Ne laser with an intermode beat frequency of 600-1000 MHz. The high beat frequency is downconverted to 5 MHz such that the phase change of the interferometer output is precisely measured with a displacement resolution of 0.1 nm. A thermal control scheme is adopted to stabilize the cavity length of the He-Ne plasma tube such that a frequency stability of 2 parts in 10(9) is obtained by suppression of frequency drifts caused by t he phenomena of frequency pulling and polarization anisotropy. This two-longitudinal-mode He-Ne laser yields a high output power of 2.0 mW, which permits multiple measurements of as many as 10 machine axes simultaneously.