| 摘要 |
<p>A far infrared lens has a lens core made of an inorganic crystal material having a refractive index of 1.74 or less at a wavelength of 10 µm, and a coating layer made of an organic material relatively thinly covering the entire surface of the lens core. At least one surface of the lens core is formed into a spherical surface and a diffraction grating is provided on the surface of the coating layer located on at least one spherical surface. Alternatively, both surfaces of the lens core are formed into spherical surfaces and an aspheric surface is provided on the surface of the coating layer located on at least one spherical surface.</p> |
