Patent ID: 6010756
Filing Date: 2000-01-04
Classification: C23C,G02B

Abstract:
A method of depositing a rugate filter coating for reflecting at least a portion of at least one electromagnetic wavelength band on a substrate, the coating having an index of refraction that varies with the depth thereof, the method comprising the steps of:placing the substrate in an apparatus capable of depositing the coating by a plasma-enhanced chemical vapor deposition process, the apparatus capable of depositing a coating from a mixture of at least two gases, said apparatus having means to control the mixture ratio of said at least two gases as a function of time;calculating the required continuous refractive index profile of the coating necessary to reflect the at least a portion of the at least one electromagnetic wave length band;calculating the required depth of the coating necessary to reflect the at least a portion of the at least one electromagnetic wave length band;dividing the depth of the calculated continuous refractive index profile of the coating into a series of increments having a specific thickness;calculating the index of refraction for each of the series of increments by computing the average value of the continuously varying index of refraction over each of said increments;calculating a specific mixture of the at least two gases required to provide the index of refraction for each of the series of increments and the length of time required to deposit each increment; anddepositing the coating on the substrate bv the plasma-enhanced chemical vapor deposition process by providing the specific mixture ratio of the at least two gases to deposit each of the increments of the coating on the substrate until the entire coating is deposited.