Patent ID: 6256446
Filing Date: 2001-07-03
Classification: G02B

Abstract:
A variable attenuator having a linear response, comprising:a housing;a coupler for coupling a first fiber optic cable to the housing;a slide body slidably fitted in the housing and arranged to receive a second fiber optic cable;a cam arrangement including a cam member, a cam surface and a spring arranged to cause the slide body to move relative to the housing in a direction parallel to an axis of the second fiber optic cable in response to rotation of the cam member, said second fiber optic cable being moved together with the slide body,wherein ends of fibers in the first and second fiber optic cables face either other and an air gap is formed between the fiber ends as the slide body moves the second fiber optic cable relative to the housing, movement of the slide body in response to rotation of the cam member and the back force of the spring causing the length of said air gap to vary and variation in said air gap length causing variation in attenuation of light passing through the air gap, andwherein said cam surface is configured such that a change in said attenuation is proportional to an angle through which said cam member is rotated to vary the air gap length and is substantially linear with rotation of said cam member.