Apparatus, method and system for fluid-motion-powered modulation of a retroreflector for remote position sensing

A method of modulating a radiation signal with a chopping wheel having a propeller connected thereto, comprising the steps of:

• passing said propeller through a fluid to cause rotation of said chopping wheel;
• controlling an angular velocity of said chopping wheel;
• propagating at least a portion of an incident radiation signal through said chopping wheel;
• and
• reflecting at least a portion of the incident radiation signal to produce a reflected radiation signal;
• and
• propagating the reflected radiation signal through said chopping wheel.

A system for determining relative positions of first and second in-flight objects, comprising:

• a source of radiation carried by said first object;
• at least one fluid-motion-powered modulated reflector, mounted on said second object for reflecting a radiation signal, wherein said fluid-motion-powered modulated reflector comprises:
• a reflector for reflecting at least a portion of a radiation signal incident thereon;
• a chopping wheel disposed between a source of the radiation signal and said reflector;
• and
• a propeller that rotates in response to the passage of fluid thereover, connected to said chopping wheel to facilitate rotation thereof;
• and
• a detector, mounted on said first object, to receive the reflected radiation signal.

A fluid-motion-powered modulated reflector apparatus comprising:

• a reflector for reflecting at least a portion of a radiation signal incident thereon;
• a rotatable polarizing filter disposed between a source of the radiation signal and said reflector;
• a propeller that rotates in response to the passage of fluid thereover connected to said rotatable polarizing filter to facilitate rotation therewith;
• and
• a fixed polarizing filter covering the reflective face of said reflector and disposed between said rotatable polarizing filter and said reflector or disposed in front of said rotatable polarizing filter and said reflector.

A method of modulating a radiation signal with a rotatable polarizing filter having a propeller connected thereto, comprising the steps of:

• passing said propeller through a fluid to cause rotation of said rotatable polarizing filter;
• controlling an angular velocity of said polarizing filter;
• propagating an incident radiation signal through said rotatable polarizing filter and a fixed polarizing filter such that the radiation signal is polarized;
• reflecting at least a portion of the radiation signal to produce a reflected radiation signal;
• and
• propagating the reflected radiation signal through said rotatable polarizing filter and said fixed polarizing filter.

A system for determining relative positions of first and second in-flight objects, comprising:

• a source of radiation carried by said first object;
• at least one fluid-motion-powered modulated reflector, mounted on said second object for reflecting a radiation signal, wherein said fluid-motion-powered modulated reflector comprises:
• a reflector for reflecting at least a portion of the radiation signal incident thereon;
• a rotatable polarizing filter disposed between a source of the radiation signal and said reflector;
• a fixed polarizing filter covering the reflective face of said reflector and disposed between said rotatable polarizing filter and said reflector or disposed in front of said rotatable polarizing filter and said reflector;
• and
• a propeller that rotates in response to the passage of fluid thereover connected to said rotatable polarizing filter to facilitate rotation therewith;
• and
• a detector, mounted on said first object, to receive the reflected radiation signal.