Claims
- 1. A temperature sensor having an operating temperature range, guaranteed operating time and temperature resolution, said temperature sensor comprising an optical waveguide with a grating as a sensing section, said grating having been subjected to accelerated aging under a predetermined condition, the condition being determined to provide a displacement of a measured temperature value due to aged deterioration of the grating that is no greater than the temperature resolution when the sensor is used for the guaranteed operating time at the maximum temperature in the operating temperature range, wherein the condition of the aging is determined using the aged deterioration curve of said grating represented by C·t−α, where t represents time, and C and α represent parameters.See the attached Appendix for the changes made to effect the above claim.
- 2. The temperature sensor according to claim 1, wherein parameter α is represented as follows:α=α0·exp(−Eα/T) where:α0 and Eα are constants; and T is absolute temperature.
- 3. The temperature sensor according to claim 2, wherein parameter C is represented as follows:C=τα=[τ0·exp(−Eτ/T)]αwhere:τ0 and Eτ are constants; and T is absolute temperature.
- 4. A method for making an optical waveguide with a grating, said grating being designed to suppress deterioration of the grating within a predetermined tolerance when the grating is used for a predetermined operating time at a predetermined operating temperature, said method comprising:forming a grating at a region in an optical waveguide; and aging said grating under a condition determined according to a method comprising: setting an aged deterioration curve of said grating as a form of C·t−α, where t represents time, and α and C represent parameters; and determining said condition based on said aged deterioration curve.
- 5. A method according to claim 4, wherein said parameter α is expressed as follows:α=α0−exp(−Eα/T) where:α0 and Eα are constants; and T is absolute temperature.
- 6. A method according to claim 5, wherein said determining said condition further comprises determining a values η1 satisfying the following two expressions:where: Hm≤1η1·(t3+t2)-α0·exp(-Eα/T2)t2=exp(- ln(η1)α0·exp(-EαT2))Hm is a predetermined minimum allowable value; T2 is the predetermined operating temperature of said grating; and t3 is the predetermined operating time of said grating.
- 7. A method according to claim 6, wherein said determining said condition further comprises determining a temperature T1 and a time t1 of a heat treatment included in the aging based on said value η1.
- 8. A method according to claim 7, wherein said heating temperature T1 and said heating time t1 are set so as to satisfy the following expression:η1=t1−α0·exp(−Eα/T1).
- 9. A method according to claim 7, wherein said heating temperature T1 is 40° C. or more above said operating temperature T2.
- 10. A method according to claim 5, wherein said determining said condition comprises:setting a provisional temperature T1p and a provisional time t1p of a heat treatment included in the aging; using said temperature T1p and time t1p to determine value η1p represented by the following expression: η1p=t1p−α0·exp(−Eα/T1p) (12) using said temperature T1p and time t1p to determine value η1p to determine a time t2p, represented by the following expression: t2p=exp(- ln(η1p)α0·exp(-EαT2))where T2 is the predetermined operating temperature of said grating;using thus determined time t2p and said value η1p to determine a value Hp represented by the following expression: Hp=1η1p·(t3+t2p)-α0·exp(-Eα/T2)where t3 is the predetermined operating time of said grating; andcomparing thus determined value Hp with a predetermined minimum allowable value Hm, and defining said value η1p, temperature T1p, and time t1p as said conditions of the aging when the comparison results in Hp≧Hm.
- 11. A method according to claim 10, wherein said determining said condition comprises resetting said provisional temperature T1p and said provisional time t1p when said comparison results in Hp<Hm, and repeating said determining the value η1p, determining the time t2p, determining the value Hp and comparing Hp with Hm.
- 12. A method according to claim 10, wherein said provisional temperature T1p is 40° C. or more above said operating temperature T2.
- 13. A method according to claim 5, wherein said parameter C is expressed as follows:C=τα=[τ0·exp(−Eτ/T)]αwhereτ0 and Ep are constants; and T is absolute temperature.
- 14. A method according to claim 13, wherein said determining said condition further comprises determining a value η1 satisfying the following two expressions: Hm≤1η1·[t3+t2τ0·exp(-Eτ/T2)]-α0·exp(-Eα/T2)t2=τ0·exp(-EτT2- ln(η1)α0·exp(-EαT2))where:Hm is a predetermined minimum allowable value; T2 is the predetermined operating temperature of said grating; and t3 is the predetermined operating time of said grating.
- 15. A method according to claim 14, wherein said determining said condition further comprises determining a temperature T1 and a time t1 of a heat treatment included in the aging based on said value η1.
- 16. A method according to claim 15, wherein said heating temperature T1 and said heating time t1 are set to satisfy the following expression:η1=[t1τ0·exp(-Eτ/T1)]-α0·exp(-Eα/T1).
- 17. A method according to claim 13, wherein said determining said condition comprises:setting a provisional temperature T1p and a provisional time t1p of a heat treatment included in the aging; using said temperature T1p to determine a time t2p represented by the following expression: η1p=[t1pτ0·exp(-Eτ/T1p)]-α0·exp(-Eα/T1p)using said value η1p to determine a time t2p represented by the following expression: t2p=τ0·exp(-EτT2-ln(η1p)α0·exp(-EαT2))where T2 is the predetermined operating temperature of said grating;using thus determined time t2 p and said value η1p to determine a value Hp represented by the following expression: Hp=1η1p·[t3+t2pτ0·exp(-Eτ/T2)]-α0·exp(-Eα/T2)where t3 is the predetermined operating time of said grating; andcomparing thus determined value Hp with a predetermined minimum allowable value Hm, and defining said value η1p, temperature η1p, and time t1p as said conditions of the aging when the comparison results in Hp≧Hm.
- 18. A method according to claim 17, wherein said determining said condition comprises resetting said provisional temperature T1p and said provisional time t1p when said comparison results in Hp <Hm, and repeating said determining the value η1p, determining the time t2p, determining the value Hp and comparing Hp with Hm.
Priority Claims (3)
Number |
Date |
Country |
Kind |
9-113996 |
May 1997 |
JP |
|
10-114839 |
Apr 1998 |
JP |
|
10-258291 |
Sep 1998 |
JP |
|
RELATED APPLICATION
This a continuation-in-part application of U.S. patent application Ser. No. 09/070,799 filed on May 1, 1998, now U.S. Pat. No. 6,137,931.
US Referenced Citations (4)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
09/070799 |
May 1998 |
US |
Child |
09/343472 |
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US |