| 摘要 |
PROBLEM TO BE SOLVED: To provide an ND filter capable of uniform, flat absorption (reduction, adjustments, etc.) of light in a visible light/near-infrared light area (approximately in the range of 400 to 2,000 nm). SOLUTION: The ND filter having at least one nonwoven fabric layer precisely divides light that passes between fibers without resistance and light reflected or absorbed by fibers. In addition, the transmittance of the ND filter can be arbitrarily adjusted according to the thickness of the fiber, the basis weight of the nonwoven fabric, the thickness of the nonwoven fabric, or the like. Further, the ND filter can steadily uniformly absorb (reduce) light having a wide range of wavelength from visible light (400 to 700 nm) to near-infrared light (700 to 2,000 nm). The ND filter has a dimmer function by which target transmittance is freely obtained in the range of 0 to 80%. COPYRIGHT: (C)2006,JPO&NCIPI
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