- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Magnification-invariant surface profiling technique for structured illumination imaging and microscopy
摘要： The structured illumination (SI) surface profiling method that is fast and has a depth-independent image magnification ratio is presented. Utilizing an electrically tunable lens (ETL) makes it possible to scan the object plane rapidly and motionlessly. The change in magnification ratio that generally occurs with the variation in the focal length of an objective lens is minimized by using a 4f relay system and placing the ETL at the confocal plane. The high reflection at the uncoated membrane surfaces of the ETL is bypassed by using polarization optics. It is also proposed that the fast response of the ETL can be fully exploited by switching the scanning sequence from that of a conventional SI imaging system; performing the depth scan before the pattern shift. It is shown that the scanning speed was increased up to 25 times. The principle and the related problems of SI profiling based on an ETL are fully analyzed, and the concept is confirmed experimentally. In the experiment, scanning depth variation of 35 mm could be achieved while keeping the magnification ratio variation below 0.03. The ability of 3D profiling is demonstrated by SI imaging a cone-shape 3D object and a face-shape plaster figure. In the fields requiring fast scanning, such as an intraoral scanner or biomedical imaging, the proposing SI imaging method can be fully utilized.
关键词： Tunable Lens,Surface Profiling,Intraoral scanner,Structured Illumination,Magnification invariant
更新于2025-09-23 15:21:01
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Speckle reduction with fast electrically tunable lens and holographic diffusers in a laser projector
摘要： We proposed a speckle reduction system in the laser pico-projector. The holographic diffusers and the fast electrically tunable lens (FET lens) were adopted in the method of the speckle reduction. This research focuses on speckle reduction by the different divergence angle of the holographic diffusers. Moreover, the speckle contrast value can be further reduced by the fast electrically tunable lens. Different divergence angle of the holographic diffuser provides the different angular diversity to compare the speckle reduction ability. We propose three experimental methods to explore speckle reduction. In experiment 1, we use a holographic diffuser and the FET lens. The speckle contrast value can be reduced to 0.08353. In experiment 2, the speckle contrast value can be reduced to 0.06403 under the balance between power consumption and speckle reduction. In experiment 3, we adjust different waveforms to get lower speckle contrast value. Finally, the speckle contrast value is 0.048 at 400Hz. That is lower than 0.05 successfully. That caused the speckle phenomenon is undetectable by human eye.
关键词： laser pico-projector,speckle reduction,angular diversity,fast electrically tunable lens,holographic diffusers
更新于2025-09-12 10:27:22