美国Newport 平面刻划反射光栅

平面刻划反射光栅在特定波长下以一阶 Littrow 配置闪耀，以获得最大效率。刻划反射光栅特别适用于需要高分辨率的光谱系统。

• 在设计波长和闪耀角时效率非常高

• 槽频率的选择范围较宽（从 50 至 2400 g/mm）

• 非常适用于高分辨率光谱应用

• 铝和金涂层

• 浮法玻璃基板

• 对边宽度为 12.5、25 和 50 mm

产品规格：

特征：

平面刻划光栅结构

一般来说，对于刻划衍射光栅，槽间距决定衍射角，并且槽深度和闪耀角决定衍射能量在衍射级之间如何分布。设计用于一阶 Littrow，Newport 的平面刻划反射光栅闪耀，以在特定设计波长实现极高的单阶衍射效率。在 Newport，我们有三种刻划引擎全日制运转，每种引擎都用于生产高质量的主光栅。这些划线机提供的光栅具有三角形槽轮廓、极低的罗兰鬼线和高分辨率。使用金刚石工具对机械刻划单个槽的蒸汽金属薄涂层抛光。利用多年研究和制造经验而开发和增强的高保真铸造复制过程，我们有能力提供主光栅的副本，其质量和性能与主光栅相同。

**光栅方向

平面刻划反射光栅在以 Littrow 结构的设计波长附近使用时（即对准以便使主要衍射级的衍射角与输入光束一致）最有效率，对于特定波长，有效的起到了回射器的作用。对于闪耀光栅，可在与闪耀光栅面垂直角度的 Littrow 条件的波长处获得最大效率。由于刻划闪耀光栅不对称，因此正确的取向由基板尺寸上的箭头标记来表示。箭头在基板垂直于刻划槽的一侧，并且指向三角形槽轮廓的更陡峭的边缘。类似地，箭头指向远离光栅法线朝向面法线。箭头应指向入射（和衍射）光束。

Diffraction Grating Physics

When light encounters an obstacle such as an opaque screen with a small opening (or aperture) the intensity distribution behind the screen can look much different than the shape of the aperture that it passed through. Since light is an electromagnetic wave, its wavefront is altered much like a water wave encountering an obstruction. This diffraction phenomenon occurs because of interference between different portions of the wavefront. The resulting intensity distribution is called a diffraction pattern. Similarly, when light passes through an opaque screen consisting of multiple elongated apertures (or slits) with a fixed spacing between them, the emerging wavefronts constructively interfere to produce a diffraction pattern with intensities peaked in certain directions as shown in the figure. These directions are strongly dependent on both the slit spacing and wavelength of the incident light. Consequently, surfaces with well-defined slit locations can be used to direct light of certain wavelengths into specific directions.

全不锈钢结构

The Grating Equation

全不锈钢结构

The basic grating equation determines the discrete directions into which monochromatic light of wavelength λ is diffracted. The equation is shown below:

mλ = dG (sinα + sinβm)

The above figure illustrates this diffraction. Light of wavelength λ is incident at an angle α and diffracted by the grating (with a groove spacing dG) along a set of angles βm. These angles are measured from the grating normal, which is shown as the dashed line perpendicular to the grating surface at its center. If βm is on the opposite side of the grating normal from α, its sign is opposite. In the equation, m is the order of diffraction, which is an integer. For the zeroth order (m = 0), α and β0 are equal and opposite, resulting in the light simply being reflected, i.e., no diffraction. The sign convention for m requires that it is positive if the diffracted ray lies to the left (counter-clockwise side) of the zeroth order and negative if it lies to the right (the clockwise side). When a beam of monochromatic light is incident on a grating, the light is simply diffracted from the grating in directions corresponding to m = -2, -1, 0, 1, 2, 3, etc. When a beam of polychromatic light is incident on a grating, then the light is dispersed so that each wavelength satisfies the grating equation as shown in the figure. Usually only the first order, positive or negative, is desired and so higher order wavelengths may need to be blocked. In many monochromators and spectrographs, a constant-deviation mount is used where the wavelength is changed by rotating the grating around an axis while the angle between the incident and diffracted light (or deviation angle) remains unchanged.

超快脉冲放大

调谐到激光器偏振和输出波长的相同衍射光栅对可用于暂时压缩超快激光脉冲，从而显著增加峰值功率。当宽光谱激光脉冲入射在衍射光栅上时，各种波长分量将沿不同方向色散或衍射。如果该脉冲具有其啁啾波长（即其频率在脉冲的长度范围内逐渐增加），则与脉冲的尾部（由较短的波长组成）相比，第一光栅将以更大的角度衍射脉冲的前导部分（由较长的波长组成）。当光以相同的周期到达第二光栅时，色散将根据对称性反转并对光进行准直。来自脉冲前沿的光将通过光栅对传播更长的光路，需要更多的传播时间。如果将光栅之间的间隔选择为使传播时间差异与脉冲持续时间相匹配，则激光功率将压缩为接近瞬时的脉冲。

低罗兰鬼线

通过将干涉测量监测包含在制造刻划光栅母版的过程中，Newport 可实现光栅周期和位置不规则性最小化。由于表面周期性具有不规则性，这会显著降低鬼线或二级光谱或分配到不需要的波长-角度组合的能量的影响。由于空间频率含量低（或远大于槽间距的周期性），因此接近衍射母线且对称的鬼线称为罗兰鬼线。赖曼鬼线更远离母线，并且几乎是由不需要的与刻线密度类似的周期性造成的。罗兰鬼线和赖曼鬼线都遵循光栅方程，尽管罗兰鬼线在光谱应用中通常存在更多问题。Newport 的处理是专门设计为最大限度地减小罗兰鬼线的影响。

处理衍射光栅

由于 Newport 的平面刻划反射光栅具有精细、精确、有图案的反射表面，因此无法在不损坏条纹图案的情况下接触表面，并且可能严重降低光学性能。损坏光栅可以采取微观槽轮廓污染或变形的形式。不幸的是，对这种微观槽轮廓的损坏是不可逆的。树脂层与造型粘土类似，将保留的印记。手指上的油、水汽等污染通常也是性的。由于光栅槽轮廓的敏感特性，用户必须在处理光栅时采取预防措施。不要触摸光栅的表面；通过边缘处理光栅，并始终戴手套或指套。使用非接触式清洁方法，如干燥的压缩空气或灰尘灯泡，以去除光栅中的多余灰尘。

浮法玻璃基板

浮法玻璃通过将熔融玻璃浮在熔融金属床上制成。虽然这是用于商业窗的低成本材料，但是该生产方法会生产出统一厚度的平面，使其成为光学器件的理想选择。

特殊订单

除此处列出的光栅外，特殊定制的光栅同样适用于各种应用，包括 OEM。联系 Newport 的 Richardson Gratings 获取详细信息。