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## 物理代写|光学代考Optics代写|THE TRANSIT OF LIGHT IN THE HUMAN EYE

Because the eye is a light-detection instrument, it is of great importance to understand the interaction between light and matter in the eye. These interactions are classified on the macroscopic scale, in terms of the human scale of observation, into four main categories: refraction, reflection, scattering, and absorption.

Reflection and refraction describe macroscopic effects associated with light encountering an interface separating two media with different propagation speeds, which is represented by a change in the index of refraction. Part of the beam returns to the original medium (for example, air); this effect is reflection. Part of the beam propagates in the subsequent medium (for example, glass); this effect is refraction.
Scattering and absorption describe the microscopic interaction of light with matter and result in changes in the propagation path or a transfer of energy.
In scattering (see $\S 2.5 .3$ ), light exits the medium in a random direction without transferring to any other form of energy. The direction of light propagation changes randomly and therefore in all directions, with a strong preference for the forward direction.
On the other hand, in absorption (see $\S 2.5 .3$ ), light energy is converted into another form, usually heat. For example, during thermal absorption, light is converted into molecular oscillations (macroscopically, this is heat). Sunlight warms us precisely via the mechanism of thermal absorption. During electrochemical absorption, which is the main mechanism for light detection in the eye ( $\S 4.3)$, light energy is used to break molecular bonds. An effect often following absorption is the re-emission of light to other, longer wavelengths. The associated effects are fluorescence and phosphorescence.

## 物理代写|光学代考Optics代写|Losses due to Reflection

Any optical interface reflects part of the light energy incident on it. We are interested in the analytical expressions for the amplitude reflection coefficient $\rho$, the ratio of the reflected amplitude to the incident amplitude of the electric field $E$, and the amplitude transmission coefficient $\tau$, the ratio of the refracted (transmitted) amplitude to the incident amplitude. The subscript indices $\mathrm{i}, \mathrm{r}$, and $\mathrm{t}$ denote the incident, reflected, and transmitted electric field, respectively:
$$\rho=\frac{E_{\mathrm{r}}}{E_{\mathrm{i}}} \quad \text { and } \quad \tau=\frac{E_{\mathrm{t}}}{E_{\mathrm{i}}}$$
A sensor (the eye is a sensor) records intensity, not the electric field. Thus, the directly measurable quantities are reflectance or reflectivity $R=\rho^2$, the dimensionless ratio of the reflected light intensity to the incident light intensity, and transmittance or transmissivity $T=\tau^2$, the ratio of the refracted (transmitted) light intensity to the incident light intensity:
Reflectivity:
$$R \equiv \frac{\text { reflected light intensity } I_r}{\text { incident light intensity } I_i}$$
These are the Fresnel coefficients ${ }^{201}$ named after the French physicist Augustin-Jean Fresnel. If there are no losses, then $R+T=\rho^2+\tau^2=1$, which means that the total amount of incident light is either reflected or refracted (transmitted).

# 光学代写

## 物理代写|光学代考Optics代写|Losses due to Reflection

$$\rho=\frac{E_{\mathrm{r}}}{E_{\mathrm{i}}} \quad \text { and } \quad \tau=\frac{E_{\mathrm{t}}}{E_{\mathrm{i}}}$$

$$R \equiv \frac{\text { reflected light intensity } I_r}{\text { incident light intensity } I_i}$$

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## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。