Specifications. Title:Optical Reflectance Filter for 550nm Authors: Affiliation:. Overview
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Title:Optical Reflectance Filter for 550nm
Our LaserDyne team was presented with the challenge of creating an optical band reflect filter for the United States Military. In order to achieve the project goals specified by the United States Military, the design should allow for complete reflection of light at 550nm and completely transmit light at all other wavelengths. The filter must be built using a glass substrate and layers containing either Lithium Flouride (LiF) or Zinc Sulfide (ZnS). Since complete reflectance only at 550nm is not possible in the real world, the design calls for the smallest possible bandwidth, centered at 550nm. Two major issues of the filter design are cost and reproduction ability. We discovered that as the number of layers used in the filter increased, the production cost rose dramatically and the probability of producing a defect free filter decreased. The merits of our filter include a maximum reflectance of 90.79% at 550nm and a bandwidth of approximately 87.74nm. The filter has a total of 6 layers (3 stacks) on top of the substrate. Having fewer layers was important from a cost standpoint. Our design will only cost $3,427.48 to produce per filter in bulk (100 filters per unit). The small quantity of layers also ensures trouble-free production and minimal defects.
Figure 1: Theoretical Calculations for ZnS
Figure 2: Theoretical Calculations for LiF
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