Situ determination of refractive index of materials

A method of treating a structure of an eye, the method comprising:

• focusing a light source into the structure to a focal point having a location;
• identifying a location of the focal point in response to an optical interference signal;
• determining an index of refraction of the material in response to the location of the focal point;
• mapping the index of refraction to the structure;
• determining a profile of the structure in response to the mapping;
• and incising the structure in response to the profile of the structure.

A method of determining an index of refraction of an optically transmissive tissue material within an eye of a subject, the material defining a surface adjacent a second material having a second index of refraction which is different from the index of refraction of the optically transmissive tissue material, the method comprising:

• configuring an optical system according to a configuration, and using the optical system to direct a light and to focus the light to an actual focal point within the material;
• determining a target focal point location of the light corresponding to the configuration of the optical system and an assumed index of refraction of the material, and determining a first distance which is a distance between the target focal point location and the surface;
• using a tomography system, measuring an optical interference signal of a light returned from the actual focal point, and based on the optical interference signal, determining a peak intensity location within the material which corresponds to a peak intensity of the optical interference signal;
• determining a second distance which is a distance between the peak intensity location and the surface;
• and
• determining the index of refraction of the material based on the assumed index of refraction, the first distance, and the second distance.

A method of determining an index of refraction of an optically transmissive tissue material within an eye of a subject, comprising:

• configuring an optical system according to a first configuration, and using the optical system to direct a light and to focus the light to a first actual focal point within the material;
• determining a first target focal point location of the light with the material corresponding to the first configuration of the optical system and an assumed index of refraction of the material;
• using a tomography system, measuring a first optical interference signal of a light returned from the first actual focal point, and based on the optical interference signal, determining a first peak intensity location within the material which corresponds to a first peak intensity of the first optical interference signal;
• configuring the optical system according to a second configuration, and using the optical system to direct a light and to focus the light to a second actual focal point within the material;
• determining a second target focal point location of the light with the material corresponding to the second configuration of the optical system and the assumed index of refraction of the material;
• using the tomography system, measuring a second optical interference signal of a light returned from the second actual focal point;
• determining a first distance with the material which is a distance between the first target focal point location and the second target focal point location;
• determining a second distance with the material which is a distance between the first peak intensity location and the second peak intensity location;
• and
• determining the index of refraction of the material based on the assumed index of refraction, the first distance, and the second distance.