Imaging and characterization of tissue based upon the preservation of polarized light transmitted therethrough

A method for imaging an object located in or behind a turbid medium, said method comprising the steps of:

• (a) providing a beam of light;
• (b) polarizing the beam of light, whereby the beam of light has an initial state of polarization;
• (c) illuminating the object through the turbid medium with the polarized beam of light, whereby light consisting of a ballistic component, a snake-like component and a diffuse component emerges from the illuminated turbid medium;
• (d) detecting the degree of polarization of the emergent light to determine the extent to which the emergent light includes the ballistic and snake-like components;
• and
• (e) forming an image of the object using the detected light.

A method for imaging an object located in or behind a turbid medium, said method comprising the steps of:

• (a) illuminating the object through the turbid medium with a pulse of light, the pulse of light being passed through a polarizer and having an initial state of polarization, whereby light consisting of a ballistic component, a snake-like component and a diffuse component emerges from the illuminated turbid medium;
• (b) passing the emergent light from the illuminated turbid medium through an analyzer appropriately oriented relative to said polarizer so as to alternately transmit light of two polarization states;
• (c) collecting the emerged light in the two polarization states to measure the emerged polarized light which belongs to the ballistic and snake-like components;
• and
• (d) forming an image of the degree of polarization D of the emerged light.

A method for imaging a tissue and for identifying the tissue, said method comprising the steps of:

• (a) illuminating the tissue with a first pulse of light passing through a polarizer, the first pulse of light having an initial state of polarization, whereby light from the first pulse consisting of a ballistic component, a snake-like component and a diffuse component emerges from the illuminated tissue;
• (b) passing the light from the first pulse emergent from the illuminated tissue through an analyzer appropriately oriented relative to said polarizer so as to alternately transmit light of two polarization states;
• (c) forming an image of the degree of polarization of the emergent light from the first pulse;
• (d) illuminating the tissue with a second pulse of light having a different wavelength than the first pulse, the second pulse of light passing through a polarizer and having an initial state of polarization, whereby light from the second pulse consisting of a ballistic component, a snake-like component and a diffuse component emerges from the illuminated tissue;
• (e) passing the light from the second pulse emergent from the illuminated tissue through an analyzer appropriately oriented relative to said polarizer so as to alternately transmit light of two polarization states;
• (f) forming an image of the degree of polarization of the emergent light from the second pulse;
• (g) repeating steps (d) through (f) if required;
• and
• (h) forming an image of the tissue, said image containing information regarding the type of tissue using the images formed in steps (c) and (f).

A method for imaging an object located in or behind a turbid medium, said method comprising the steps of:

• (a) illuminating the object through the turbid medium with a first pulse of light, the first pulse of light being polarized and having an initial state of polarization, whereby light from the first pulse consisting of a ballistic component, a snake-like component and a diffuse component emerges from the illuminated turbid medium;
• (b) passing the light from the first pulse emergent from the illuminated turbid medium through one of a polarizer oriented parallel to the initial state of polarization of said first pulse of light and an analyzer oriented perpendicular to the initial state of polarization of said first pulse of light;
• (c) detecting the light from the first pulse passed through one of said polarizer and said analyzer;
• (d) illuminating the object through the turbid medium with a second pulse of light, the, second pulse of light being polarized in an initial state parallel to that of said first pulse of light, whereby light from the second pulse consisting of a ballistic component, a snake-like component and a diffuse component emerges from the illuminated turbid medium;
• (e) passing the light from the second pulse emergent from the illuminated turbid medium through the other of said polarizer and said analyzer;
• (f) detecting the light from the second pulse passed through the other of said polarizer and said analyzer;
• and
• (g) forming an image of the object in or behind the turbid medium using the light detected in steps (c) and (f).

A method for identifying a tissue, said method comprising the steps of:

• (a) illuminating the tissue with a pulse of light, the pulse of light being polarized and having an initial state of polarization, whereby light consisting of a ballistic component, a snake-like component and a diffuse component emerges from the illuminated tissue;
• (b) passing the emergent light from the illuminated tissue through one of a polarizer oriented consistent with the initial state of polarization of said pulse of light and an analyzer oriented opposite to the initial state of polarization of said pulse of light;
• (c) detecting the light passed through one of said polarizer and said analyzer;
• and
• (d) comparing the detected light to appropriate standards so as to identify the type of tissue tested.

An apparatus for imaging an object in a turbid medium, the apparatus comprising:

• (a) means for illuminating an object in a turbid medium from a first side thereof with light, said light being polarized and having an initial state of polarization, whereby light consisting of a ballistic component, a snake-like component and a diffuse component emerges from the turbid medium;
• (b) polarization means for alternately passing the parallel and perpendicular components of the light emergent from the turbid medium;
• (c) means for detecting the parallel and perpendicular components of the emergent light;
• (d) means for calculating one of a ratio and a difference of the parallel and perpendicular components of the emergent light;
• (e) means for forming an image of the object in the turbid medium using said one of said ratio and said difference.

An apparatus for imaging an object in a turbid medium, the apparatus comprising:

• (a) a light source for emitting a beam of light towards the turbid medium;
• (b) means for polarizing the beam of light prior to illuminating the turbid medium;
• (c) analyzing means for selectively passing the light emergent from the turbid medium based upon its polarization;
• (d) means for detecting the analyzed light;
• and
• (e) means for generating a one or two or three dimensional map of the degree of polarization (D or d or p) of the emerged light.