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Issue 3 ， 2014
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Stray light analysis and suppression of rigid endoscope system
Abstract：On the structure of optical system, the causes of stray light of a rigid endoscope and its suppression methods were explored to eliminate the stray light and to improve its imaging performance. Firstly, the stray light in the optical and mechanical system was simulated and analyzed by ray tracing in Lighttools. By analysis of the stray light path, it points out that the stray light of the optical system comes from the total reflection of a relay system and an objective system. Then, with the possible causes, the suppression methods for the stray light were proposed, including adjusting objective structure and controlling ray path. Finally, a rigid arthroscopy with a Field of View(FOV) of 70° and an outer diameter of 2.7 mm was designed to suppress the stray light. With proposed methods, the Modulation Transfer Function(MTF) reaches diffraction limit, the values of all fields are higher than 0.4 at 100 lp/mm, and the size of spot diagram is smaller than 4 μm. Besides the high-definition imaging, simulation demonstrates that the stray light has been moved out entirely in the optical system, and the system shows excellent imaging quality.Keywords：optical design;medical imaging;rigid endoscope;stray light- 70
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- 13
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Published：2020-08-13 -
Single objective stereo microscopy based on red-and-blue dual-apertures
Abstract：To obtain a 3D model of microscopic dynamic samples, a 3D microscopic imaging method based on a single objective and redblue dualapertures was proposed and a corresponding 3D microscopic specimen system for capturing images was established. In the system, the dual apertures covered with a red and a blue filters were respectively placed in the exit pupil plane of the objective. When it was illuminated by a white light, the color CCD in the imaging plane of objective could receive the perspective views of specimen expressed by red and blue images respectively at one exposure. The stereo image with an optical parallax for the specimen could be obtained by digital image processing, and the 3D model of the specimen could be further reconstructed by a phase matching algorithm. Experimental results indicate that the system has reconstructed the 3D model with a Central Depth Plane (CDP) up to 241.50 μm.As compared with double-objective 3D microscopic imaging systems, the proposed system is more compact and simpler and can obtain a 3D model of microscopic dynamic sample at one exposure, so that the system has important application prospects on microscopes and endoscopes.Keywords：microscopic imaging;3D microscopy;binocular stereo matching;dual-apertures;single objective- 70
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- 9
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Published：2020-08-13 -
Measurement of extinction ratio by dual modulation
Abstract：A method by using magnetooptical modulation and light source modulation techniques was proposed to measure the extinction ratio of a polarizing prism precisely, and an extinction ratio measurement system was also established based on the two modulation techniques. Firstly, the system′s measurement model was derived according to the Jones matrix describing manner of polarized light. By using a magnetooptical modulator, the optical axis angle between a polarizer and a measured polarizing prism was precisely located. Then, by using a chopper to modulate the square wave of a light source, the impact of noises on the system measurement accuracy was eliminated and the system could measure the light intensity value accurately after the measured polarizing prism′s axis was located precisely. Finally, the polarizing prism was measured for a number of times and the data were averaged. The experimental results indicate that the measurement accuracy of extinction ratio for the polarizing prism can be 10-6, which verifies the effectiveness and stability of the method. The system is characterized by high stability, high accuracy, and can offer the references for the performance test and engineering applications of polarized devices.Keywords：polarized light;magneto-optical modulation;light source modulation;extinction ratio;polarizing prism- 80
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Published：2020-08-13
Modern Applied Optics
Micro/Nano Technology and Fine Mechanics
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