Optical module

Details Optical module Optical module

2001-10-03

2004-03-30

Epps, Georgia (Department: 2873)

Optical: systems and elements

Lens

With support

C385S092000

Reexamination Certificate

active

06714365

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical module into which an optical element is incorporated.
2. Description of the Related Art
Currently, practical use has been made of optical modules which have a variety of functions and comprise various optical elements such as an optical filter or optical crystal.
The optical module includes a package in which various optical elements are housed. More particularly, the optical element is directly fixed to the bottom surface of the package by means of adhesive such as an epoxy-based adhesive. In general, the package is formed of a metal material and the bottom surface of the package is formed flat by cutting using end mills or the like. The flatness of the bottom surface is critical in establishing an accurate mutual alignment between optical elements.
However, the bottom surface has a number of scratches caused by cutting and the depth of the scratches is not uniform. Therefore, the bottom surface of the package has a rough surface in comparison with the surface of optical elements such as an optical filter or optical crystal. Thus, when an optical element is fixed to the bottom surface of the package by means of adhesive, the thickness of an adhesive layer between the bottom surface and the optical element varies greatly because of the roughness of the bottom surface.
On the other hand, the adhesive expands or contracts as the ambient temperature varies. Such expansion or contraction of the adhesive tends to increase the variation in thickness of the adhesive layer in accordance with the difference in the thickness. Accordingly, a variation in ambient temperature would cause the adhesive layer to impose an uneven stress to the optical element, producing strain in the optical element. Consequently, the optical elements become misaligned with each other, causing the optical property of the optical module to greatly depend on variations in ambient temperature.
To solve the aforementioned problems, it can be contemplated to polish the bottom surface of the package to reduce the roughness of the bottom surface. However, additional polishing of the bottom surface would increase the overall time and cost required for fabrication of the package, thereby making the resulting optical module expensive.
An object of the present invention is to provide an inexpensive optical module whose optical property depends less on the ambient temperature and can maintain the stability.
SUMMARY OF THE INVENTION
An optical module according to the present invention comprises a package, an optical element, and a member interposed between the optical element and the package. The surface of the member to which the optical element is bonded is smoother than the surface of the package to which the member is fixed.


REFERENCES:
patent: 5016965 (1991-05-01), Marshall et al.
patent: 2003/0081914 (2003-05-01), Steinberg et al.

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