Based on the theoretical model and simulation, this paper presents the acoustic detective sensitivity of three types of optical fiber acoustic sensors – RIM-FODS (reflective intensity modulated fiber optic displacement sensor), extrinsic F-P (Fabry-Perot) interferometer and all-fiber photoelastic interference sensor. Three designed optical fiber acoustic sensor systems are implemented to analyze the performance of each type and tested to investigate the detective sensitivity at 1kHz 94dB SPL (sound pressure level). The experimental results are in good agreement with those obtained by theoretical analysis and simulation.
Traditional optical imaging system cannot achieve full field of view and high magnification simultaneously. Enslaved to resolution of detector array, the imaging field vision and magnification cannot be satisfied at the same time. Zoom lens can only vary the magnification for the center field of view, and it is not able to show the large observation field of view and local optical magnified image of either area at one glance. When the focal length of zoom lens reaches the long end, the field of vision will reduce, which leads to missing of marginal targets. The shortage of traditional imaging technique will entail inconvenience. In this paper, we propose a new scheme of geometrical optics imaging system combining two imaging optical path of different focal length in one optical system and the two optical paths image on the same detector array simultaneously. The local optical path can image for arbitrary position of targets and its focal length is variable using liquid lens. The final local variable magnification imaging optical system is shown as example. We offer the detailed design and simulation results, which shows that this kind of optical path configure can image for large field of view and arbitrary local detail at the same sight and maintain acceptable imaging performance.
Imaging optical system with coaxial common aperture near-infrared illumination containing both imaging optical path and illumination light path is established. The imaging optical path is coaxial and shares the front objective lens with the illumination light path. An aspherical short-focus single lens is adopted to decrease the blink surfaces in numbers and simplifies the optical structure. The ghost imaging path is traced backwards to locate the stray light. Absorption region set in the reflector plate eliminates the ghost images induced by the illumination rays reflected by front objective lens surfaces. A uniform rod is adopted to mix the light of near-infrared source, and the reflector plate locates in the conjugate position of aperture stop of both imaging optical path and the illumination light path, which can reduce the impact of occlusion of the reflector plate and ensure the illumination uniformity of the target object. The optical system covers the full field of view of 54° and imaging spectrum range of 450nm to 860nm. We offer the detailed design and simulation results. It shows that this optical system can make good imaging performances and illumination uniformity, and maintain compact structure.
Sensor surface or division plate of optoelectronic imaging system can retroreflect incident beams energy strongly. This so-called cat eye effect is useful for engineering application, such as range finding. However, it is hazardous for the hidden photoelectric equipment be detected by a laser active device based on cat eye effect. In this paper, we propose a new scheme of geometrical optics imaging system to change the beam incident angle on the detector surface. Thus, the reflected beam energy could pass through a completely different route and be blocked by the lens aperture, so it cannot be reflected back to the active detection device. The aim of anti-detection for the lens design is achieved by usage of prism and phase corrector. A prism plays a role of bending beam direction of propagation to deviate from the optic axis and maintaining the direction of image surface simultaneously. The cemented achromatic prism used herein is to correct the chromatic aberration induced by the prism. And we also adopt a fixed phase corrector to compensate the large amount of oblique astigmatism following a prism in nonparallel beams. A final anti-detection optical imaging lens is shown as example. We offer the detailed design and simulation results, which shows that this kind of optics system can reduce the cat eye reflected signal substantially and maintain acceptable imaging performance.