Wavelength determining apparatus, method and program for thin film thickness monitoring light

Abstract

A wavelength determining apparatus for thin film thickness monitoring light so as to determine the wavelength of the monitoring light which is projected to an optical thin film under deposition and transmitted through or reflecting from the optical thin film, comprising a means, related to optical intensity change of the monitoring light, to calculate a first stopping index value to stop deposition of said optical thin film whose thin film thickness reaches desired thin film thickness in each nominated wavelength of the plural monitoring light, and a means to determine the nominated wavelength of the monitoring light in the plural monitoring light based on the first stopping index value of each calculated nominated wavelength.

What is claimed is:  
     
         1 . A multi-layer optical thin film filter comprising plural deposited optical thin films so as to obtain a predetermined wavelength profile in a target wavelength band, wherein an optical thin film thickness for each of said optical thin films is not less than (2n+1)/4 times (“n” is a natural number excluding zero.) of center wavelength which ranges from ½ times to {fraction (3/2)} times of the wavelength in said target wavelength band.  
     
     
         2 . A multi-layer optical thin film filter comprising plural deposited optical thin films so as to obtain a predetermined wavelength profile in a target wavelength band, wherein an optical thin film thickness for each of said optical thin films is designed with using basic optical thin film thickness which is (2n+1)/4 times (“n” is a natural number excluding zero.) of center wavelength which ranges from ½ times to {fraction (3/2)} times of the wavelength in said target wavelength band.  
     
     
         3 . The multi-layer optical thin film filter as claimed in  claim 2 , wherein said optical thin film thickness for each of said optical thin films is designed with using said basic thin film thickness for an initial value by fitting a theoretical value which expresses said wavelength profile in said target wavelength band with using optical thin film thickness or light of at least one layer of said optical thin films as parameter to a predetermined target wavelength profile in said target wavelength band.  
     
     
         4 . A designing method for a multi-layer optical thin film filter comprising plural deposited optical thin films so as to obtain a predetermined wavelength profile in a target wavelength band, comprising a step that optical thin film thickness for each of said optical thin films is designed using basic optical thin film thickness which is (2n+1)/4 times (“n” is a natural number excluding zero.) of center wavelength which ranges from ½ times to {fraction (3/2)} times of the wavelength in said target wavelength band.  
     
     
         5 . The design method of the multi-layer optical thin film filter as claimed in  claim 4 , comprising a step to optimize the optical thin film thickness of at least one layer of said plural thin films so as to obtain said predetermined wavelength profile.  
     
     
         6 . A multi-layer optical thin film filter comprising plural deposited optical thin films, wherein optical thin film thickness for each of said optical thin films has a predetermined wavelength spectrum in a predetermined gain equalization band and a predetermined wavelength spectrum in a pumping light transmission band other than said gain equalization band.  
     
     
         7 . The multi-layer optical thin film filter as claimed in  claim 6 , wherein the optical thickness for each of said optical thin film is designed by fitting calculation using predetermined initial optical thickness so as to lessen a first error between a theoretical value which expresses a wavelength profile in said gain equalization band with using the optical thickness for each of said optical thin films as parameter and a target wavelength spectrum value in the corresponding gain equalization band, and a second error between a theoretical value which expresses a wavelength spectrum in said pumping light transmission band with using the optical thickness for each of said optical thin films as parameter and a target wavelength spectrum value in the corresponding pumping light transmission band.  
     
     
         8 . The multi-layer optical thin film filter as claimed in  claim 7 , wherein an initial value of the optical thin film thickness for each of said optical thin films during said fitting is designed so that a cutting off wavelength band in said wavelength profile does not overlap said pumping light wavelength band.  
     
     
         9 . The multi-layer optical thin film filter as claimed in  claim 8 , wherein an initial value of optical thickness for each of said optical thin films during said fitting is designed so that an edge of a short wavelength side of said cutting off wavelength band in the wavelength profile overlaps said wavelength band for gain equalization.  
     
     
         10 . A multi-layer optical thin film filter, wherein optical thin film thickness for each of said optical thin films is designed by fitting with using desired optical thin film thickness for an initial value so as to lessen a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than predetermined pumping light wavelength band with using optical thin film thickness for each of optical thin films and target wavelength values in a predetermined wavelength band, and a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band in the case that a transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is smaller than a minimum transmission rate required in said pumping light wavelength band.  
     
     
         11 . The multi-layer optical thin film filter as claimed in  claim 10 , wherein said second error between said theoretical value which expresses the wavelength profile in said pumping light wavelength band with using the optical thin film thickness for each of said optical thin films as parameter and said wavelength profile value in the corresponding pumping light wavelength band becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is larger than the minimum transmission rate required in said pumping light wavelength band.  
     
     
         12 . A multi-layer optical thin film filter comprising plural deposited optical thin films, wherein optical thin film thickness for each of said optical thin films is designed by fitting with using predetermined optical thin film thickness for an initial value so as to lessen a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of optical thin films and a target wavelength value in a predetermined wavelength band, and a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band in the case that a transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is larger than an allowable maximum transmission rate required in said pumping light wavelength band.  
     
     
         13 . The multi-layer optical thin film filter as claimed in  claim 12 , wherein said second error between said theoretical value which expresses the wavelength profile in said pumping light wavelength band with using the optical thin film thickness for each of said optical thin films as parameter and said wavelength profile value in the corresponding pumping light wavelength band becomes zero in the case that the transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is smaller than an allowable maximum transmission rate required in said pumping light wavelength band.  
     
     
         14 . A designing method for a multi-layer optical thin film filter comprising plural deposited optical thin films to design thin film thickness for each of said optical thin films, comprising a step to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of optical thin films and a target wavelength value in a desired wavelength band, and a step to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band, and a step to design optical thin film thickness for each of said optical thin films so as to lessen the calculated first and second errors respectively.  
     
     
         15 . A designing method for a multi-layer optical thin film filter comprising plural deposited optical thin films to design thin film thickness for each of said optical thin films, comprising a step to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a step to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band in the case that a transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is smaller than a minimum transmission rate required in said pumping light wavelength band, and a step to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
     
     
         16 . The designing method for a multi-layer optical thin film filter as claimed in  claim 15  comprising a step that the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and the wavelength profile value in the corresponding pumping light wavelength band becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is larger than the minimum transmission rate required in said pumping light wavelength band.  
     
     
         17 . A designing method for a multi-layer optical thin film filter comprising plural deposited optical thin films to design optical thin film thickness for each of said optical thin films, comprising a step to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a desired wavelength band, and a step to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band in the case that a transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is larger than an allowable maximum transmission rate in said pumping light wavelength band, and a step to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
     
     
         18 . The designing method for a multi-layer optical thin film filter as claimed in  claim 17  comprising a step to the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and the wavelength profile value in the corresponding pumping light wavelength band becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is smaller than the allowable maximum transmission rate in said pumping light wavelength band.  
     
     
         19 . A thin film thickness designing apparatus for a multi-layer optical thin film filter comprising plural deposited optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a target wavelength profile value in the corresponding pumping light wavelength, and a means to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
     
     
         20 . A thin film thickness designing apparatus for a multi-layer optical thin film filter comprising plural deposited optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength in the case that a transmission rate corresponding to a target wavelength profile in said pumping light wavelength band is smaller than an allowable maximum transmission rate in said pumping light wavelength band, and a means to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
     
     
         21 . The thin film thickness designing apparatus for a multi-layer optical thin film filter as claimed in  claim 20 , comprising a means that the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using the optical thin film thickness of each of said optical thin films as parameter and the wavelength profile value in the corresponding pumping light wavelength becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is smaller than the allowable maximum transmission rate in said pumping light wavelength band.  
     
     
         22 . A thin film thickness designing apparatus for a multi-layer optical thin film filter comprising plural deposited optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a wavelength profile value in the corresponding pumping light wavelength band in the case that transmission rate to correspond to target wavelength profile in said pumping light wavelength band is larger than an allowable maximum transmission rate in said pumping light wavelength band, and a means to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
     
     
         23 . The thin film thickness designing apparatus for a multi-layer optical thin film filter as claimed in  claim 22 , comprising a means that the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using the optical thin film thickness for each of said optical thin films as parameter and the target wavelength profile value in the corresponding pumping light wavelength becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is smaller than the allowable maximum transmission rate in said pumping light wavelength band.  
     
     
         24 . A computer program performed by a computer for a multi-layer optical thin film filter comprising plural deposited optical thin films to design thin film thickness for each of said optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a target wavelength profile value in the corresponding pumping light wavelength, and a means to design optical thin film thickness for each of said optical thin films so as to lessen the calculated first and second errors respectively.  
     
     
         25 . A computer program performed by a computer for a multi-layer optical thin film filter comprising plural deposited optical thin films to design thin film thickness for each of said optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with optical thin film thickness for each of said optical thin films as parameter and a target wavelength profile value in the corresponding pumping light wavelength, and a means to design optical thin film thickness for each of said optical thin films so as to lessen the calculated first and second errors respectively.  
     
     
         26 . The computer program performed by a computer for a multi-layer optical thin film filter as claimed in  claim 25 , comprising a means that the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and the target wavelength profile value in the corresponding pumping light wavelength becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is larger an the minimum transmission rate required in said pumping light wavelength band.  
     
     
         27 . A computer program performed by a computer for a multi-layer optical thin film filter comprising plural deposited optical thin films to design thin film thickness of each of optical thin films, comprising a means to calculate a first error between a theoretical value which expresses a wavelength profile in a predetermined wavelength band other than a predetermined pumping light wavelength band with using optical thin film thickness for each of said optical thin films and a target wavelength value in a predetermined wavelength band, and a means to calculate a second error between a theoretical value which expresses a wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films as parameter and a target wavelength profile value in the corresponding pumping light wavelength in the case that a transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is larger than an allowable maximum transmission rate in said pumping light wavelength band, and a means to design optical thin film thickness for each of said optical thin films by fitting with using predetermined optical thin film thickness for an initial value so as to lessen the calculated first and second errors respectively.  
     
     
         28 . The computer program performed by a computer for a multi-layer optical thin film filter as claimed in  claim 27 , comprising a means that the second error between the theoretical value which expresses the wavelength profile in said pumping light wavelength band with using optical thin film thickness for each of said optical thin films and the target wavelength profile value in the corresponding pumping light wavelength becomes zero in the case that the transmission rate corresponding to the target wavelength profile in said pumping light wavelength band is smaller than the maximum allowable transmission rate in said pumping light wavelength band.  
     
     
         29 . An optical amplifier comprising an rare earth element doped optical fiber to amplify an optical signal, an pumping light source which projects pumping light to excite said rare earth element, a combiner which combines pumping light projected by said pumping light source with said optical signal and projects said pumping light to said rare earth element doped optical fiber, and the multi-layer thin film filter as claimed in  claim 6  which is located in an output side for pumping light of said combiner and a down stream side for said optical signal.  
     
     
         30 . A wavelength division multiplex system which transmits plural optical signals with different wavelength, comprising an optical sender to send said plural optical signals to an optical transmission route, the optical amplifier as claimed in  claim 29  which amplifies said plural optical signals sent by said sender and transmitted through said optical transmission route in a lump, and an optical receiver which receives said plural optical signals amplified by said optical amplifier and transmitted through said optical transmission route.  
     
     
         31 . A wavelength determining method for thin film thickness of monitoring light so as to determine wavelength of said monitoring light which is projected to an optical thin film under deposition and transmitted through or reflecting from said optical thin film, comprising a step, related to a optical intensity change of said monitoring light, to calculate a first stopping index value to stop deposition of said optical thin film whose thin film thickness reaches desired thin film thickness in each nominated wavelength of said plural monitoring light, and a step to determine the nominated wavelength of said monitoring light in said plural monitoring light based on the first stopping index value of each calculated nominated wavelength.  
     
     
         32 . A wavelength determining apparatus for thin film thickness of monitoring light so as to determine wavelength of said monitoring light which is projected to an optical thin film under deposition and transmitted through or reflecting from said optical thin film, comprising a means, related to a optical intensity change of said monitoring light, to calculate a first stopping index value to stop deposition of said optical thin films whose thin film thickness reaches desired thin film thickness in each nominated wavelength of said plural monitoring light, and a meaning to determine the nominated wavelength of said monitoring light in said plural monitoring light based on the first stopping index value of each calculated nominated wavelength.  
     
     
         33 . The wavelength determining apparatus for thin film thickness of the monitoring light as claimed in  claim 32 , wherein the first stopping index value related to the optical intensity change of said monitoring light is a parameter for a function of a deposition time which expresses the optical intensity change.  
     
     
         34 . The wavelength determining apparatus for thin film thickness of the monitoring light as claimed in  claim 32 , wherein the first stopping index value related to the optical intensity change of said monitoring light is a B/A value which expresses a ratio between a changing range (A) of the optical intensity of transmitted or reflecting light of said optical thin film and a changing value (B) from external value of the optical intensity of transmitted or reflecting light when said optical thin film thickness reaches desired thickness.  
     
     
         35 . The wavelength determining apparatus for a thin film thickness of the monitoring light as claimed in  claim 32 , related to the optical intensity change of said monitoring light, comprising a means to calculate a second stop index value so as to stop deposition when said thin film thickness reaches the desired thickness in plural change nominated wavelengths where a predetermined wavelength change is added to each of the nominated wavelengths of said monitoring light, a means to calculate a changing value between the first stop index value and the second stop index value in each of plural calculated nominated wavelengths, and a means to determine the nominated wavelength of said monitoring light based on the calculated changing value in said plural nominated wavelengths.  
     
     
         36 . The wavelength determining apparatus for a thin film thickness of the monitoring light as claimed in  claim 35 , wherein said means to calculate the first and second stop index values is a means to calculate the first and second stop index values respectively in each of said optical thin film layers and said nominated wavelength in the case that said optical thin film is deposited on a deposition substrate in plural layers, said means is a means to calculate the changing value between the first and the second stop index values in each of the calculated optical thin films and each of said plural nominated wavelengths, and said means is a means to determine the nominated wavelength of said monitoring light based on the calculated changing value in said nominated wavelength.  
     
     
         37 . The wavelength determining apparatus for a thin film thickness of the monitoring light as claimed in  claim 35 , wherein said means is a means to calculate the first and second stop index values respectively in each of said optical thin film layers and said nominated wavelength in the case that said optical thin film is deposited on said deposition substrate in plural layers, said means is a means to calculate the changing value between the first and the second stop index values in each of the calculated optical thin films and each of the plural nominated wavelengths, and said means to is a means to determine the nominated wavelength of said monitoring light based on total sum of the changing values between the calculated first and second stop index values in the total optical thin film layers from said plural nominated wavelengths.  
     
     
         38 . A program to determine a wavelength of a monitoring light which is projected to an optical thin film deposited on a deposition substrate and transmitted through or reflecting from said optical thin film, related to a optical intensity change of said monitoring light, comprising a means to calculate a first stop index value so as to stop deposition when said optical thin film thickness reaches a desired thin film thickness in each of said plural nominated wavelengths of said monitoring light, a means to determine the plural nominated wavelengths of said monitoring light based on the first stop index value in each of the calculated nominated wavelengths in said plural nominated wavelength.  
     
     
         39 . The program as claimed in  claim 38 , related to the optical intensity change of said monitoring light, comprising a means to calculate a second stop index value so as to stop deposition when said thin film thickness reaches the desired thickness in plural change nominated wavelengths where a predetermined wavelength change is added to each of the nominated wavelengths of said monitoring light, a means to calculate the changing value between the first stop index value and the second stop index value in each of plural calculated nominated wavelengths, and means to determine the nominated wavelength of said monitoring light based on the calculated changing value in said plural nominated wavelengths.  
     
     
         40 . A deposition system to set an optical thin film thickness of an optical thin film deposited on a deposition substrate with a deposition material evaporated from a deposition material source with using a monitoring light with a wavelength determined by the wavelength determining apparatus for the optical thin film thickness monitoring light as claimed in  claim 32  to  37  as a design value, related to the optical intensity change of said monitoring light, comprising a memorizing means to memorize a stop index value so as to stop deposition of said optical thin film corresponding to said design value, a receiving means to receive said monitoring light with a wavelength determined by said optical thin film thickness monitoring light from the light which is projected to said wavelength determining apparatus for the optical thin film monitoring light and transmitted through or reflecting from said optical thin film, a means to judge if the optical thin film thickness corresponding to said optical intensity change reaches said stop index value based on the optical intensity change of the received monitoring light and said stop index value memorized by said memorizing means and to prevent the deposition material evaporated by said deposition material source from deposited on said deposition substrate if it is judged that the optical thin film thickness reaches said stop index value.  
     
     
         41 . A deposition control method to control optical thin film thickness of each optical thin film so as to correspond to a predetermined design thin film thickness of each optical thin film thickness with using a monitoring light which is transmitted through or reflecting from said optical thin film when multi-layer thin films comprising plural optical thin films deposited on a deposition substrate with a deposition material evaporated by a deposition material source, comprising a memorizing step to memorize data to express an optical transmitting loss profile and/or a reflecting loss profile in a desired wavelength band of multi-layer optical thin films actually deposited by a deposition apparatus, a estimating step to estimate an optical thin film thickness error which usually occurs in an optical thin film deposited by said deposition apparatus based on the wavelength profile of said multi-layer thin films memorized by said memorizing step, a control step to perform said optical thin film thickness control based on the design optical thin film thickness for each of said optical thin films and the estimated optical thin film thickness error.  
     
     
         42 . A deposition control system used for a deposition apparatus to deposit multi-layer thin films consisting of plural optical thin films on a deposition substrate with a deposition material evaporated by a deposition material source to control optical thin film thickness of each optical thin film so as to correspond to pre-designed thin film thickness of each optical thin film with using a monitoring light which is transmitted through or reflecting from each of said optical thin films, comprising a control means to perform deposition control based on an estimated thin film thickness error which usually occurs in the optical thin films deposited by said deposition apparatus.  
     
     
         43 . The deposition control system as claimed in  claim 42 , wherein the estimated thin film thickness error which usually occurs in the optical thin films deposited by said deposition apparatus is a thin film thickness error estimated based on the data of an optical transmission profile or a reflection loss profile in a desired wavelength band of multi-layer thin films where deposition has been completed.  
     
     
         44 . The deposition control system as claimed in  claim 43 , wherein the estimated thin film thickness error which usually occurs in the optical thin films deposited by said deposition apparatus is estimated as an error from said pre-designed thin film thickness.  
     
     
         45 . The deposition control system as claimed in  claim 42  or  43 , wherein the estimated thin film thickness error which usually occurs in the optical thin films deposited by said deposition apparatus is estimated with converting the thin film thickness error into a delay time during the deposition.  
     
     
         46 . A deposition control system used for a deposition apparatus to deposit multi-layer thin films consisting of plural optical thin films on a deposition substrate with a deposition material evaporated by a deposition material source to control optical thin film thickness of each optical thin film so as to correspond to a pre-designed thin film thickness of each optical thin film with using a monitoring light which is transmitted through or reflecting from each of said optical thin films, comprising a memorizing means to memorize data to express an optical transmission profile in a predetermined wavelength band of multi-layer thin films actually deposited by a deposition apparatus, an thin film thickness error estimation means to estimate a thin film thickness error which usually occurs in said optical thin films deposited by said deposition apparatus based on optical transmission loss profile data of said multi-layer thin films memorized by said memorizing means, and a control means to perform optical thin film thickness control based on the design thin film thickness and the estimated thin film thickness error.  
     
     
         47 . The deposition control system as claimed in  claim 46 , wherein said thin film thickness error estimation means comprises an estimation means to estimate said thin film thickness error as an error from said design thin film thickness, and an adjustment means to adjust said design thin film thickness so as to cancel the estimated error.  
     
     
         48 . The deposition control system as claimed in  claim 47 , wherein said estimation means for the thin film thickness error is a means to estimate said thin film thickness error with converting said thin film thickness error into a delay time during the deposition.  
     
     
         49 . The deposition control system as claimed in  claim 46 , wherein said estimation means for the thin film thickness error comprises a means to set plural delay times, a memorizing means to memorize functional data to express a optical intensity change of a monitoring light obtained from said design thin film thickness, a calculation means to calculate a change of a monitoring light from each thin film layer under deposition during the simulation, a means to calculate parameter of the functional data of each thin film layer by fitting of said functional data with using the calculated optical intensity change, a calculation means to calculate a thin film thickness of each layer of an optical thin film under deposition for the deposition control based on functional data including the calculated parameter, a means to calculate a thin film thickness of each layer of optical thin films in each delay time when a deposition time is changed from calculated thin film thickness of each layer by each delay time, a means to calculate an error in each of said delay time with comparing an optical transmission loss profile data of a multi-layer thin film actually deposited with the optical transmission loss profile data calculated in each of said delay time, and a means to calculate a optimized delay time with comparing errors in each of the calculated delay times.  
     
     
         50 . The deposition control system as claimed in  claim 49 , wherein said thin film thickness control means comprises a means to monitor the luminous change of monitoring light from the optical thin film layer deposited on said deposited material, a means to calculate the parameter of the functional data corresponding to said optical thin film layer by fitting of said functional data with using the optical intensity change, a means to calculate the time when said optical thin film thickness becomes said design thin film thickness, a means to prevent said deposition material from deposited on said deposition substrate when the present time becomes the time that said delay time is deducted from the calculated time.  
     
     
         51 . A computer program used for a deposition apparatus to deposit multi-layer thin films consisting of plural optical thin films on a deposition substrate with a deposition material evaporated by a deposition material source to control an optical thin film thickness of each optical thin film so as to correspond to pre-designed thin film thickness of each optical thin film with using a monitoring light which is transmitted through or reflecting from each of said optical thin films, and to perform said deposition control based on the thin film thickness error pre-estimated by said deposition apparatus which usually occurs in the optical thin film deposited by said deposition apparatus.  
     
     
         52 . A computer program used for a deposition apparatus to deposit multi-layer thin films consisting of plural optical thin films with a deposition material evaporated by a deposition material source so as to control to meet a pre-designed optical thin film thickness for each of the optical thin films with using a monitoring light which is transmitted through or reflecting from said optical thin films, comprising a means, related to a optical intensity change of said monitoring light, to calculate a first stopping index value to stop deposition of said optical thin films where a thin film thickness reaches a desired thin film thickness in each nominated wavelength of said plural monitoring lights, and a meaning to determine the nominated wavelength of said monitoring light in said plural monitoring lights based on the first stopping index value of each calculated nominated wavelength.