美***Newport 平面刻劃反射光柵
產(chǎn)品規(guī)格：
特征：
平面刻劃光柵結(jié)構(gòu)
***般來說，對于刻劃衍射光柵，槽間距決定衍射角，并且槽深度和閃耀角決定衍射能量在衍射***之間如何分布。設(shè)計用于***階 Littrow，Newport 的平面刻劃反射光柵閃耀，以在特定設(shè)計波長實現(xiàn)極高的單階衍射效率。在 Newport，我們有三種刻劃引擎全日制運轉(zhuǎn)，每種引擎都用于生產(chǎn)高質(zhì)量的主光柵。這些劃線機提供的光柵具有三角形槽輪廓、極低的羅蘭鬼線和高分辨率。使用金剛石工具對機械刻劃單個槽的蒸汽金屬薄涂層拋光。利用多年研究和制造經(jīng)驗而開發(fā)和增強的高保真鑄造復(fù)制過程，我們有能力提供主光柵的副本，其質(zhì)量和性能與主光柵相同。
**光柵方向
平面刻劃反射光柵在以 Littrow 結(jié)構(gòu)的設(shè)計波長附近使用時（即對準(zhǔn)以便使主要衍射***的衍射角與輸入光束***致）***有效率，對于特定波長，有效的起到了回射器的作用。對于閃耀光柵，可在與閃耀光柵面垂直角度的 Littrow 條件的波長處獲得***大效率。由于刻劃閃耀光柵不對稱，因此正確的取向由基板尺寸上的箭頭標(biāo)記來表示。箭頭在基板垂直于刻劃槽的***側(cè)，并且指向三角形槽輪廓的更陡峭的邊緣。類似地，箭頭指向遠(yuǎn)離光柵法線朝向面法線。箭頭應(yīng)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.
全不銹鋼結(jié)構(gòu)
The Grating Equation
全不銹鋼結(jié)構(gòu)
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.
超快脈沖放大
調(diào)諧到激光器偏振和輸出波長的相同衍射光柵對可用于暫時壓縮超快激光脈沖，從而顯著增加峰值功率。當(dāng)寬光譜激光脈沖入射在衍射光柵上時，各種波長分量將沿不同方向色散或衍射。如果該脈沖具有其啁啾波長（即其頻率在脈沖的長度范圍內(nèi)逐漸增加），則與脈沖的尾部（由較短的波長組成）相比，第***光柵將以更大的角度衍射脈沖的前導(dǎo)部分（由較長的波長組成）。當(dāng)光以相同的周期到達第二光柵時，色散將根據(jù)對稱性反轉(zhuǎn)并對光進行準(zhǔn)直。來自脈沖前沿的光將通過光柵對傳播更長的光路，需要更多的傳播時間。如果將光柵之間的間隔選擇為使傳播時間差異與脈沖持續(xù)時間相匹配，則激光功率將壓縮為接近瞬時的脈沖。
低羅蘭鬼線
通過將干涉測量監(jiān)測包含在制造刻劃光柵母版的過程中，Newport 可實現(xiàn)光柵周期和位置不規(guī)則性***小化。由于表面周期性具有不規(guī)則性，這會顯著降低鬼線或二***光譜或分配到不需要的波長-角度組合的能量的影響。由于空間頻率含量低（或遠(yuǎn)大于槽間距的周期性），因此接近衍射母線且對稱的鬼線稱為羅蘭鬼線。賴曼鬼線更遠(yuǎn)離母線，并且?guī)缀跏怯刹恍枰呐c刻線密度類似的周期性造成的。羅蘭鬼線和賴曼鬼線都遵循光柵方程，盡管羅蘭鬼線在光譜應(yīng)用中通常存在更多問題。Newport 的處理是專門設(shè)計為***大限度地減小羅蘭鬼線的影響。
處理衍射光柵
由于 Newport 的平面刻劃反射光柵具有精細(xì)、精確、有圖案的反射表面，因此無法在不損壞條紋圖案的情況下接觸表面，并且可能嚴(yán)重降低光學(xué)性能。損壞光柵可以采取微觀槽輪廓污染或變形的形式。不幸的是，對這種微觀槽輪廓的損壞是不可逆的。樹脂層與造型粘土類似，將保留的印記。手指上的油、水汽等污染通常也是性的。由于光柵槽輪廓的敏感特性，用戶必須在處理光柵時采取預(yù)防措施。不要觸摸光柵的表面；通過邊緣處理光柵，并始終戴手套或指套。使用非接觸式清潔方法，如干燥的壓縮空氣或灰塵燈泡，以去除光柵中的多余灰塵。
浮法玻璃基板
浮法玻璃通過將熔融玻璃浮在熔融金屬床上制成。雖然這是用于商業(yè)窗的低成本材料，但是該生產(chǎn)方法會生產(chǎn)出統(tǒng)***厚度的平面，使其成為光學(xué)器件的理想選擇。
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