Novel Aerogel-Filled Diffractive Optical Elements

新型气凝胶填充衍射光学元件

• 批准号: 9461091
• 负责人: Donald Thornton
• 金额: $ 7.48万
• 依托单位: Advanced Environmental Research Group Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-02-01 至 1996-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9461091&HistoricalAwards=false
• 关键词: Novel; Aerogel; Filled; Diffractive; Optical

This Small Business Innovation Research Phase I project describes how one can protect the grooves of the microscopic surface relief pattern in optical diffractive elements by filling them with aerogel, a very fine quartz foam, which protects the grooves against dust and grease and thereby improves the usefulness of various types of these optical diffractive elements by saving them from severely degraded optical performance. In applications of coherent optics, the use of optical diffractive elements is spreading rapidly and they are even important in certain non laser devices. This project combines two recent material technologies and applies them to two important national needs, one of which is energy savings in buildings through innovative window designs, the other is to develop novel optical devices to be used in laser devices. The diffractive structures for windows (when eventually manufactured industrially in large sheets) would be placed in contact with the upper part of a window. Sunlight incident from the southeast, south, or southwest on the structure is diffracted with high efficiency towards the ceiling and from there shines downwards into dark corners, so called `daylighting.` The role of the aerogel is to fill the delicate diffractive grooves and thus protect them against damage from handling and against dust accumulation. The flat aerogel film would further improve thermal insulation and could also serve as a substrate for deposition of heat (infrared) reflecting layers. In that case, the structure would combine the function of daylighting (redirecting of incident light) with keeping out heat rays (low-E glazing) and be thermally insulating. Aerogel is the optimal material to combine with the diffractive plastic for various reasons: 1) Its refractive index is very close to that of air, which is essential in maintaining large efficiency over a wide range of incident angles as will be elaborated on later. 2) Aerogel is optically quite transparent, particularly in a thin layer. 3) Aerogel is lightweight and has recently been deposited in micron thick films. 4) The trapped air gives aerogel very excellent thermal insulating properties.

这个小型企业创新研究第一阶段项目描述了如何通过填充气凝胶（一种非常细的石英泡沫）来保护光学衍射元件中微观表面浮雕图案的凹槽，气凝胶可以保护凹槽免受灰尘和油脂的影响，从而通过防止光学性能严重下降来提高各种类型的光学衍射元件的实用性。在相干光学的应用中，光学衍射元件的使用正在迅速普及，它们在某些非激光设备中甚至很重要。该项目结合了两种最新的材料技术，并将其应用于两个重要的国家需求，其中之一是通过创新的窗户设计实现建筑物节能，另一个是开发用于激光设备的新型光学器件。用于窗口的衍射结构（当最终以大片材进行工业制造时）将被放置为与窗口的上部接触。从东南部、南部或西南方向入射到结构上的阳光会高效地衍射到天花板，并从那里向下照射到黑暗的角落，即所谓的“采光”。气凝胶的作用是填充精致的衍射凹槽，从而保护它们免受搬运造成的损坏和灰尘积聚。平坦的气凝胶薄膜将进一步改善隔热性，并且还可以用作沉积热（红外）反射层的基材。在这种情况下，该结构将结合采光（重新引导入射光）和阻挡热射线（低辐射玻璃）的功能，并具有隔热功能。出于多种原因，气凝胶是与衍射塑料结合的最佳材料：1）它的折射率非常接近空气的折射率，这对于在宽入射角范围内保持高效率至关重要，稍后将详细说明。 2) 气凝胶在光学上非常透明，特别是在薄层中。 3) 气凝胶重量轻，最近已沉积成微米厚的薄膜。 4) 截留的空气赋予气凝胶非常优异的隔热性能。