Multi-purpose sensor system and sensing method using internally reflected light beams

A sensor system comprising:

• a first layer having first and second surfaces and a first index of refraction;
• a second layer having a second index of refraction which is less than the first index of refraction;
• means for generating a first diffuse light beam which is initially directed along a first line through the first layer from the first surface to the second surface in a first direction;
• means for sensing a portion of the first diffuse light beam reflected back through the first layer to the first surface as an incident of the first diffuse light beam impinging upon the second layer,
• the second layer being disposed on the first layer so as to define an interface between the first and second layers, the portion of the first diffuse light beam reflected through the first layer to the first surface as an incident of the first diffuse light beam impinging the interface;
• and
• means coupled to the sensing means for determining the index of refraction of the second layer as a function of the distance along the first surface between the first line and the reflected portion of the first diffuse beam.

A method of determining the properties of a medium, the method comprising the steps of:

• generating a first diffuse light beam;
• passing the first diffuse light beam through a first medium having a first index of refraction;
• causing a portion of the first diffuse light beam to be initially directed along a first line through the first medium in a first direction, to impinge upon a second medium having a second index of refraction less than the first index of refraction and to reflect back into the first medium;
• and
• sensing the location relative to the first line of the portion of the first diffuse light beam reflected back into the first medium.

A method of determining the properties of a medium, the method comprising the steps of:

• generating a first diffuse light beam;
• passing the first diffuse light beam through a first surface of a first medium having a first index of refraction;
• causing a portion of the first diffuse light beam to be initially directed along a first line through the first medium, to impinge upon a second medium having a second index of refraction less than the first index of refraction and to reflect back to the first surface,
• the causing step further comprising causing the portion of the first diffuse light beam to impinge an interface defined between the first and second media and reflect back to the first surface;
• sensing the portion of the first diffuse light beam reflected back to the first surface;
• measuring the distance along the first surface between the first line and the portion of the first diffuse light beam reflected back to the first surface;
• and
• determining the index of refraction of the second medium as a function of the distance along the first surface between the first diffuse light beam and the portion of the first diffuse light beam reflected back to the first surface.

A sensor system comprising:

• a first layer having first and second surfaces and a first index of refraction;
• a second layer having a second index of refraction which is less than the first index of refraction;
• a third layer disposed between the first layer and the second layer having a thickness and a third index of refraction which is less than the first index of refraction and greater than the second index of refraction,
• the second layer being disposed on the third layer so as to define an interface between the second and third layers;
• means for generating a first diffuse light beam which is initially directed along a first line through the first layer in a first direction from the first surface to the second surface;
• means for sensing a portion of the first diffuse light beam reflected back through the first layer to the first surface as an incident of the first diffuse light beam impinging upon the interface;
• and
• means coupled to the sensing means for determining the thickness of the third layer as a function of the distance along the first surface between the first line and the reflected portion of the first diffuse beam.

A method of determining the properties of a medium, the method comprising the steps of:

• generating a first diffuse light beam;
• passing the first diffuse light beam through a first surface of a first medium having a first index of refraction;
• causing a portion of the first diffuse light beam to be initially directed along a first line through the first medium in a first direction, to impinge upon a second medium having a second index of refraction less than the first index of refraction and to reflect back to the first surface including causing the portion of the first diffuse light beam to pass through a third medium having a thickness and a third index of refraction which is less than the first index of refraction and greater than the second index of refraction, the third medium disposed between the first and second media, and causing the portion of the first diffuse light beam to impinge an interface defined between the second and third media and to reflect back to the first surface;
• sensing the portion of the first diffuse light beam reflected back to the first surface;
• measuring the distance along the first surface between the first line and the portion of the first diffuse light beam reflected back to the first surface;
• and
• calculating the thickness of the third medium as a function of the distance along the first surface between the first direction of the diffuse light beam and the portion of the first diffuse light beam reflected back to the first surface.