Abstract
In this paper, a method of using a one-dimensional position-sensitive detector (PSD) by replacing charge-coupled device (CCD) to measure the movement of the interference fringes is presented first, and its feasibility is demonstrated through an experimental setup based on the principle of centroid detection. Firstly, the centroid position of the interference fringes in a fiber Mach-Zehnder (M-Z) interferometer is solved in theory, showing it has a higher resolution and sensitivity. According to the physical characteristics and principles of PSD, a simulation of the interference fringe’s phase difference in fiber M-Z interferometers and PSD output is carried out. Comparing the simulation results with the relationship between phase differences and centroid positions in fiber M-Z interferometers, the conclusion that the output of interference fringes by PSD is still the centroid position is obtained. Based on massive measurements, the best resolution of the system is achieved with 5.15, 625 μm. Finally, the detection system is evaluated through setup error analysis and an ultra-narrow-band filter structure. The filter structure is configured with a one-dimensional photonic crystal containing positive and negative refraction material, which can eliminate background light in the PSD detection experiment. This detection system has a simple structure, good stability, high precision and easily performs remote measurements, which makes it potentially useful in material small deformation tests, refractivity measurements of optical media and optical wave front detection.
Highlights
Laser interferometry, with its advantages of large measuring range, high resolution and accuracy, etc., has been widely used in the field of precision and ultra-precision measurement [1]
When the interference fringes lie on the photosensitive surface of the position-sensitive detector (PSD), the output of the PSD is demodulated by a post-processing circuit
With the displacement platform moving in the forward direction, the characteristic curve of the PSD output under different operating distances and the movement of interference fringes is shown in Figure 7, where the slope of curves at different distances between the fiber end and PSD were obtained and exhibited perfect in smoothness and regularity
Summary
With its advantages of large measuring range, high resolution and accuracy, etc., has been widely used in the field of precision and ultra-precision measurement [1]. As the light splitting and interference in the fiber optic Sagnac and Michelson interferometers are done in the same coupler, this kind of structure is not good for PSD detection of interference fringes. Extensive research on interference fringe measurements has been carried out These studies can be generally divided into two categories: fringe centerline methods and full grayscale methods. The fringe centerline method has more advantages in detection speed, but has less location precision than the full grayscale method [20] Both methods have to collect interference fringes by using CCD or Complementary Metal-Oxide-Semiconductor (CMOS). This paper proposes a novel method for interference fringe centroid detection based on the full grayscale method, which has a simple algorithm, and avoids the complex image processing by taking PSD as a detection device with low cost and a stable structure
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