Velocity Measurement of a Highspeed Underwater Projectile With Laser Barriers

Jinhui Wu,Ji Liu

doi:10.1109/access.2021.3073910

Jinhui Wu, Ji Liu

Open Access

https://doi.org/10.1109/access.2021.3073910

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Abstract

To improve the precision of velocity measurements for high-speed underwater projectiles and meet the requirements for device terminal alarms, a method for identifying and measuring high-speed underwater projectiles with a large-area laser barrier was proposed. The absorption of laser transmission underwater and the relationship between scattering and suspended particles were simulated and analyzed. An optical system consisting of a waterproof modulated laser transceiver probe, multifiber transmission and a retroreflector was designed to decrease the large optical energy dissipation. The laser beam was expanded to form a triangular barrier with a Powell prism. The fiber array surrounding the prism receives the reflected laser light from the retroreflector. The other end of the optical fiber is coupled to a PIN-PD detector through a narrowband filter. The output electric signal is then processed by an amplifier, demodulator and low-pass filter. The shortcomings of traditional split-type and multielement optical structures in water were effectively overcome by this compact integrated probe structure, and the effective area was expanded to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 m \times 2 m$ </tex-math></inline-formula> . The velocity of high-speed underwater steel balls and lead blocks, the simulated projectiles, was acquired accurately to verify the feasibility of velocity measurement for high-speed underwater projectiles with laser barriers.

Highlights

The velocity measurement of a high-speed underwater projectile is essential for measuring motion parameters and the terminal alarm of an attacked object
There are two ways to realize laser barriers: multilaser arrays and geometric optical expansion. The advantages of the former are light power concentration and a better signal-to-noise ratio (SNR), but this approach can suffer from complex technology, discontinuous laser barriers, low resolution affected by laser spacing and poor reliability
An integrated optical transceiver probe consisting of a laser coupled with a Powell lens and a fiber array was designed

Summary

INTRODUCTION

The velocity measurement of a high-speed underwater projectile is essential for measuring motion parameters and the terminal alarm of an attacked object. Large-area real-time detection and motion parameter acquisition are critical for short-range defense and a characteristic analysis of high-speed projectile motion [8]–[14]. A detection device with an underwater light modulation unit and an overwater signal processing unit is designed This includes an underwater laser, a Powell lens, a retroreflector, a fiber array surrounding a Powell lens, an integrated waterproof probe, a heat dissipation structure, a large area PIN-PD detector and fiber bundle coupling detection. A law of the change in the water resistance and the water environment for the high-speed underwater projectile can be quantitatively measured and analyzed, which is the basis for the measurement method to obtain ballistic characteristics of underwater high-speed projectiles and can satisfy the needs for short-range detection and the development and velocity measurement of underwater weapon equipment

INFLUENCE OF WATER ON UNDERWATER LASER PROPAGATION

EXPERIMENTS AND ANALYSIS

VELOCITY MEASUREMENT

CONCLUSION