Bidirectional optical module and optical time domain reflectometer equipped with the bidirectional optical module

An optical time domain reflectometer that tests loss characteristics of an optical fiber, comprising:

• a bidirectional optical module that emits light toward said optical fiber and receives light returning from the optical fiber;
• a bidirectional optical module drive unit that drives said bidirectional optical module to emit light with predetermined timing;
• an electrical signal conversion unit that converts light having entered said bidirectional optical module to an electrical signal;
• and
• a signal processing unit that determines through calculation the loss characteristics of said optical fiber based upon said electrical signal resulting from the conversion executed by said electrical signal conversion unit, wherein:
• said bidirectional optical module includes:
• a light emitting element that emits light to enter said optical fiber;
• a light receiving element that receives light having exited the optical fiber;
• a light branching optical element that is partially transmissive and partially reflective and guides light having exited said optical fiber to said light receiving element as parallel light via open space;
• and
• a stray light shielding member having an opening formed therein, through which the light to enter said light receiving element passes, wherein the stray light shielding member is disposed between said light branching optical element and said light receiving element substantially parallel to a light receiving surface of the light receiving element.

A bidirectional optical module comprising:

• a light emitting element that emits light to enter an optical fiber;
• a light receiving element that receives light having exited the optical fiber;
• a light branching optical element that is partially transmissive and partially reflective and guides the light having exited said optical fiber to said light receiving element as parallel light via open space;
• a stray light shielding member having an opening formed therein, through which the light to enter said light receiving element passes, wherein the stray light shielding member is disposed between said light branching optical element and said light receiving element;
• and
• a light condensing element that condenses the light having become branched via said light branching optical element onto said opening at said stray light shielding member, wherein the light condensing element is disposed between said light branching optical element and said stray light shielding member, and a focus of the condensed light is the same point as said opening.

An optical time domain reflectometer that tests loss characteristics of an optical fiber, comprising:

• a bidirectional optical module that emits light toward said optical fiber and receives light returning from the optical fiber;
• a bidirectional optical module drive unit that drives said bidirectional optical module to emit light with predetermined timing;
• an electrical signal conversion unit that converts light having entered said bidirectional optical module to an electrical signal;
• and
• a signal processing unit that determines through calculation the loss characteristics of said optical fiber based upon said electrical signal resulting from the conversion executed by said electrical signal conversion unit, wherein:
• said bidirectional optical module includes:
• a light emitting element that emits light to enter said optical fiber;
• a light receiving element that receives light having exited the optical fiber;
• a light branching optical element that is partially transmissive and partially reflective and guides the light having exited said optical fiber to said light receiving element as parallel light via open space;
• a stray light shielding member having an opening formed therein, through which the light to enter said light receiving element passes, wherein the stray light shielding member is disposed between said light branching optical element and said light receiving element;
• and
• a light condensing element that condenses the light having become branched via said light branching optical element onto said opening at said stray light shielding member, wherein the light condensing element is disposed between said light branching optical element and said stray light shielding member, and a focus of the condensed light is the same point as said opening.