To solve the problem that the type and area of macular disease are not easy to identify due to the irregular scale and unobvious characteristics of macular disease region on retinal OCT images, an improved YOLOv8n macular disease detection model is proposed, and a data set of retinal macular disease detection is established. Firstly, the feature pyramid module of bidirectional weighted feature fusion was added. Secondly, the attention mechanism was introduced. Finally, the novel loss function was replaced. The improved model can complete the multi-scale and irregular multi-objective training task of retinal maculopathy. The experimental results show that the improved model has a good effect on the self-built data set. The accuracy of central serous macular degeneration, macular hole, and choroidal neovasculation can reach 97.7%, 97.8%, and 97.4%, respectively, and can accurately identify the location of the lesion.
In order to investigate the relationship between the interface parameters of an optical interface/system and its polarization characteristics, a three-dimensional (3D) polarization ray-tracing Mueller algorithm is proposed in this paper. Firstly, using the optical design simulation software CODE V or ZEMAX, the vector modeling of the optical system and the pupil sampling or field of view sampling of the incident light are carried out. Secondly, according to the surface type of each optical interface in the optical system and whether the optical coating is plated, the 3D polarization ray-tracing of each optical interface is carried out, and the 3D Mueller matrix Ml (9×9 order) of each optical interface under the respective local coordinate system is calculated. Then, a 3×3 order rotation transformation matrix R is introduced by using the rotation transformation of the global coordinate system, and the 3D Mueller matrix Mg (9×9 order) of each optical interface under the global coordinate system is obtained. Based on the 3D polarization algorithm proposed in our published paper, the 3D Mueller matrix M of each sampled ray through whole optical system is calculated. Finally, if the polarization state of the incident light of the optical system is known, the polarization state of the emitted light can be accurately calculated. Especially, the 3D polarization ray-tracing Mueller algorithm is not only suitable for handle the totally, partial and unpolarized light through the optical system, but also suitable for quantitative calculation of the polarization properties of an arbitrary surface, including spherical/aspherical/free-form surface.
We develop herein a new optimization modulation method for the three-dimensional (3D) spectral data cubes (SDC) based on the use of a linear encoding scheme of the intrinsic chromatic aberration, especially for snapshot multispectral or hyperspectral imaging systems. The mathematical model of the linear chromatic aberration modulation is established that provides the theoretical guidelines on the optimal design of 3D SDC for snapshot spectral imaging systems. Theoretical calculations and spectral simulations of an optical system are conducted and are shown to match closely, thus demonstrating that the proposed linear encoding scheme can be used as a valid modulation method for 3D SDC. This study also addresses the mutual restriction of spectral and spatial resolutions in the studied imaging systems. Overall, the proposed method is expected to create new possibilities for high-resolution, low-cost spectral imaging with simple designs.
As part of investigating the human perception of polarized light, Haidinger’s brushes (HB) is well-known optical phenomena. Although differences in the human polarization perception were well known there was a limited quantifying to them. This paper presents a 3D Stokes model of the human polarized light perception, views the human perception of polarized light as a multivariable applied optics problem to simulation and explored the optical phenomena of Haidinger’s brushes. The images comparison verifies that the simulation patterns and detected images are consistent which proves the model is appropriate for simulating polarization perception of the human eye. Then this paper explored the optical limitations of perception and macula density. The combination of the 3D Stokes model and experimental verification opens up new possibilities to become an early diagnostic method for eye polarization sensitivity and macular degeneration. The objective is to give purpose and new mathematics understanding to the biomedical optical phenomenon.
This study evaluates the polarization state persistence of differently polarized light as they propagate through wet haze (PM2.5), in forward transmission. The investigated wavelength range extends from ultraviolet (UV) to short-wave infrared (SWIR) light. Using a polarization tracking Monte Carlo simulation for a range of particle sizes, wavelengths, relative refractive indices, and propagation distances, we find that both vertically-linearly- and right-handed-circularly-polarized light show superior polarization state persistence at a wavelength of 2.4μm. While the persistence increases gradually for increasing wavelengths, the study also reveals an anomaly, a persistence peak for wet haze with 2μm particles and 0.36μm wavelength. We further compare the polarization state persistence characteristics of vertically linearly and right circularly polarized light. Circular polarization persists better than linear for wet haze in wavelengths of 0.36, 0.543, and 1μm. While with the increase of wavelength and the decrease of particle size, linear polarization gradually persisted better than circular polarization.
KEYWORDS: Light scattering, Scattering, Polarization, Polarimetry, 3D modeling, Photon polarization, Environmental sensing, 3D metrology, Monte Carlo methods, Mie scattering
A three-dimensional (3D) polarimetric tracking model is proposed to calculate scattering interactions between light and media, where a 9×1 coherency or Stokes vector is used to represent the scattered 3D polarized light. Compared with the present Monte Carlo program, this model not only address the continuous rotations problem of the reference plane at least 2 to 3 times, but also realizes the statistics tracking of 3D vibration distribution (i.e., 3D polarization state) for the scattered light in real time. In this paper, we introduce two 3D cartesian coordinate systems: a global coordinate system of an entire scattering environment, and a local coordinate system of a scattering event. Within the proposed 3D polarimetric tracking model, the polarization transformation effect (PTE) related to every scattering event is preciously tracked in corresponding local coordinate system, and the calculated 3D PTE has a 9×9 coherency transformation matrix or Mueller matrix mathematically. Importantly, by utilizing only one rotation of coordinate system, the final 3D polarization transformation effect of an entire scattering environment can be uniquely determined by successive multiplication of all 9×9 matrices characterizing scattering events. The study can be widely applied in several applications of biomimetic polarization navigation, remote sensing, marine surveillance and environmental security to preciously quality the PTE of multitudinous scattering environments.
According to the requirement of a wide-viewing-angle retroreflector (WVAR) that the max divergence angle cannot exceed 9 mrad, we have made an optimal design of WVAR with radius of 30 mm (n=1.95375@ wavelength of 632.8 nm) to be used to be the reference light in polarization interferometry. Therefore, it is particularly important to calculate its polarization properties accurately. We have applied the three-dimensional (3D) coherency polarization calculus to analyze the designed WVAR, and the theoretical results are in agreement with the simulation results by the FRED software. Finally, it can be concluded that the designed WVAR has a very good ability of polarization-maintaining.
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