This paper proposes a fabrication method for realizing all-optical AND and NOR logic gates based on polarization holography. During the recording process, two specially designed polarization holograms are recorded at the dual-region position of the polarization-sensitive material. During the reconstruction process, two reading waves in different directions are used as two input lightwaves. The background lightwave is added to the propagation direction of the two reconstructed waves, and the two reconstructed waves superimposed with the background lightwave are used as two output lightwaves. The light intensity of the two output lightwaves, together, defines the logic signal of the final output. The all-optical AND and NOR logic gates fabricated using this method have the advantages of simple structure, low cost, and fast response.
Polarization grating (PG) divides the incident wave into the left- and right-handed circularly polarized waves, the intensities of two waves depending on the state of polarization of incident wave. Large deflection angle of the commercial PG is usually made by the grating cascade due to the limit of grating period. While using the tensor polarization holography theory, arbitrary deflection angles of PGs have been designed, where the polarization-sensitive material phenanthraquinone-doped polymethyl methacrylate (PQ/PMMA) is utilized as the recording medium in our experiments. We have made PG with the deflection angle of 40°.
In the past, we used hand-made holographic data storage materials for research and storage, but these materials have many problems, such as the experiment has a certain degree of non-repeatability, and the data storage system performance is unstable. This work uses an automated chamber to prepare photopolymers without manual operation. The automation room will complete all material fabrication processes except the initial weighing and pouring. Compared with hand-made materials, the automatically made materials have no bubbles due to the special mold design. The overall production process is carried out under the condition of constant temperature and humidity.
There are many ways to realize null reconstruction in polarization holography, which can be divided into two types. One is the null reconstruction without exposure response coefficient constraint, and the other is the null reconstruction limited by the exposure response coefficient. On the basis of previous studies, we have further studied these two types of null reconstruction, and obtained the necessary conditions for realizing the two types of null reconstruction under arbitrary interference angle and polarization state.
Polarization holography has gained traction with the development of tensor theory. It primarily focuses on the interaction between polarization waves and photosensitive materials. By introducing the polarization characteristics of light into conventional holography, more degrees of freedom can be provided to control optical information. Based on the polarization modulation of polarization hologram, we propose a method to realize bifocal-polarization holographic lens in volume hologram. Two foci can be generated simultaneously or separately by changing the polarization state of the reading wave. The material used is a PQ/PMMA polarization sensitive medium, the thickness is 1.5mm. The bifocal-polarization holographic lens has 112 mm clear aperture and 446mm focal length.
Acousto-optic tunable filter (AOTF) is a new type of light splitter with fast tuning, stable structure and portability. In this paper, a hyperspectral microscopic imaging system is constructed by combining non-collinear AOTF with optical inverted microscopy. The feasibility of data augmentation based on hyperspectral images for object detection of skin squamous cell carcinoma is studied. The hyperspectral images collected from unstained sections of skin squamous cell carcinoma are processed into dataset. At the same time, the mature open source object detection model is selected and trained for 20,000 times. Using the trained model to detect the lesion area of other unstained sections, it is found that the model trained by hyperspectral image dataset has a good ability to distinguish the non-lesion area, and there is no false detection. And the model has a relatively accurate detection ability for large lesion area, but the results of the model for small lesion area are not ideal. After analysis, it is considered that the number of samples can be increased firstly, especially in small lesions, and the same to the hyperspectral images. In addition, the model for lesion detection can be further optimized. By increasing the complexity of the model, the model can learn more details and information in the image during the training process. The preliminary results of the experiment prove that hyperspectral imaging is feasible for data augmentation of lesion object detection dataset. This paper provides a new method for the object detection data augmentation of skin squamous cell carcinoma.
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