A study on image recognition of three-dimensional objects by undestroyed photorefractive optical memory using two wavelengths

两种波长无损光折变光存储器三维物体图像识别研究

基本信息

批准号：
09650064
负责人：
NIIMI Tomohide
金额：
$ 2.11万
依托单位：
Nagoya University (1998)Tottori University (1997)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650064/
关键词：
Holography Photorefractive effect Undestroyed reading BaTiO_3 LiNbO_3 Optical memory Multi-image memorization Image recognition

项目摘要

Photorefractive crystal is very promising as a medium of hologram memory because it does not require a process of development unlike an usual photographic plate and it has a large capacity of memory by three-dimensional storage of the information of an objective wave. However, when using a photorefractive crystal like a lithium niobate (LiNbO3) with a long-term storage of memory, it needs long time for writing process. In general, the use of the same wavelength as the writing process gradually erases the information through the reading process. Therefore, a new method that enables both quick writing and long-term readout has been expected. In this study, as a method for undestroyed readout, we propose the use of laser beam with different wavelength from the writing process and carry out fundamental experiments for its effectiveness. In addition, we apply the photorefractive memory to the image recognition of three-dimensional objects.A photorefractive crystal of barium titanate (BaTiO3 … More ), which has a transmissibility strongly dependent on the wavelength in the visible spectrum, was employed for the experiments of readout without erasing the stored information. A YAG laser (532 nm) was used as a light source for the writing process and an infrared LD (785 nm) for the reading process. The two wavelengths correspond to the high sensitive and insensitive regions of BaTiO3, respectively. The experiments made clear that the information stored quickly by the shorter wavelength from the YAG laser can be read out by the longer wavelength from the LD for about 10 times longer-term than readout by the original shorter wavelength. However, a whole image of the stored information could not be reproduced because of discrepancy of the Bragg angles between the shorter and longer wavelengths. Broadening the range of incident angle of the readout light by use of a cylindrical lens turned out to be effective for improvement of the reproduced image.A LiNbO3 crystal was used in the experiments for image recognition. The diffractive beam intensity, which depends on the similarity between the memorized image and the input image, was measured. A preliminary experiment using four two-dimensional images as the objects made clear that it was possible to recognize a specific image among other images by comparison of diffractive beam intensities. For recognition of three-dimensional objects, three coins were used as the objects. The three-dimensional objects could be distinctly recognized by the existence of the diffractive beam alone owing to the closer Bragg condition. The combination of the undestroyed readout and the three-dimensional recognition using a photorefractive crystal can be applied to identification of an object, position sensing, and so on. Less

非常有望作为全息图记忆的媒介进行光致晶的晶体，因为它不需要与通常的照相板不同，并且通过三维物镜信息的三维存储，它具有很大的记忆力。但是，当使用具有长期存储器的光晶晶体（如硝酸锂（Linbo3））时，它需要长时间的写作过程。通常，使用相同的波长作为写作过程会通过阅读过程逐渐消除信息。因此，一种新方法可以预期快速写作和长期读数。在这项研究中，作为一种未扎根读数的方法，我们提出使用具有不同波长的激光束与写作过程不同，并进行了基本实验。此外，我们将光折射记忆应用于三维对象的图像识别。钛酸钡的光赋形晶体（batio3…更多），该晶体具有可见频谱中的可见波长的可传输性，用于读取存储信息的实验。将YAG激光器（532 nm）用作写作过程的光源，而红外LD（785 nm）用于阅读过程。这两个波长分别对应于Batio3的高灵敏和不敏感区域。实验明确指出，可以通过YAG激光器较短波长迅速存储的信息可以通过LD的较长波长读出比原始较短波长更长的长期波长约10倍。但是，由于较短波长和更长的波长之间的bragg角度差异，无法复制存储的信息的全部图像。通过使用圆柱形镜头来扩大读取光的入射角范围，可有效地改善复制的图像。在实验中使用了linbo3晶体进行图像识别。测量了衍射光束强度，取决于记忆图像和输入图像之间的相似性。使用四个二维图像作为对象的初步实验明确表明，通过比较衍射束强度，可以在其他图像中识别特定图像。为了识别三维对象，将三枚硬币用作对象。由于较近的布拉格条件，单独的衍射梁的存在可以明显地识别三维对象。使用光折磨晶体的未扎合读数和三维识别的组合可以应用于对象，位置传感等的识别。较少的