Hon Hai Precision Industry Co., Ltd.

Ga Lane Chen

Charles Chengyea Leu

A structure of a film filter includes a plurality of film layers made of a film stack material and a substrate wafer which said film layers are deposited on at a temperature substantially higher than a room temperature and retained to after being cooled to the room temperature. The substrate wafer has a coefficient of thermal expansion greater than that of the film stack material so as to generate compressive forces upon the associated film layers, thus resulting in the film filter having a negative temperature drift coefficient.

Thin film filter having negative temperature drift coefficient

A method for making thin film filters having a negative temperature drift coefficient are the subject of the present invention. Such filters can achieve better optical control within an operational temperature range from &#x2212;5&#xb0; C. to 70&#xb0; C. degrees. A first embodiment of the present invention includes: 1. providing a substrate wafer which has a coefficient of thermal expansion (CTE) greater than that of a selected film stack material; 2. polishing the substrate wafer; 3. depositing thin film layers made of the film stack material on the substrate wafer at a temperature substantially higher than room temperature; 4. cooling the substrate-film stack laminate to room temperature, thus forming a convex-shaped laminate; 5. cutting the cooled laminate into pieces. A second embodiment includes the steps of: 1. providing a laminate composed of a glass substrate and a film stack; 2. using at least one ion beam source to bombard the film stack of the laminate with high energy ions; 3. cutting the bombarded laminate into pieces.

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Fremont, CA, United States of America

Ga Lane Chen