Photoabsorption remote sensing (PARS) imaging methods

A method of visualizing details in a sample, comprising:

• generating radiative and non-radiative signals in the sample at an excitation location using an excitation beam, the excitation beam being focused below a surface of the sample;
• interrogating the sample with an interrogation beam directed toward the excitation location of the sample, the interrogation beam being focused below the surface of the sample;
• detecting light from the sample, the detected light including a portion of the interrogation beam returning from the sample, wherein the detected light is indicative of the generated radiative and the non-radiative signals, wherein detecting the light includes detecting the generated radiative and non-radiative signals over time;
• and
• determining an evolution time of the detected generated radiative and non-radiative signals.

A method of visualizing details in a sample, comprising:

• generating radiative and non-radiative signals in the sample at an excitation location using an excitation beam, the excitation beam being focused below a surface of the sample;
• interrogating the sample with an interrogation beam directed toward the excitation location of the sample, the interrogation beam being focused below the surface of the sample;
• and
• detecting light from the sample, the detected light including a portion of the interrogation beam returning from the sample, wherein the detected light is indicative of the generated radiative and the non-radiative signals,
• wherein a wavelength of the excitation beam is configured such that the sample absorbs two or more photons simultaneously, wherein the wavelength is equal to twice a predetermined wavelength.

A method of visualizing details in a sample, comprising:

• generating radiative and non-radiative signals in the sample at an excitation location using an excitation beam, the excitation beam being focused below a surface of the sample;
• interrogating the sample with an interrogation beam directed toward the excitation location of the sample, the interrogation beam being focused below the surface of the sample;
• and
• detecting light from the sample, the detected light including a portion of the interrogation beam returning from the sample, wherein the detected light is indicative of the generated radiative and the non-radiative signals, wherein the interrogation beam includes a chirped-pulse;
• and
• spatially separating various wavelength components of the interrogation beam.

A method of visualizing details in a sample, comprising:

• generating radiative and non-radiative signals in the sample at an excitation location using an excitation beam, the excitation beam being focused below a surface of the sample;
• interrogating the sample with an interrogation beam directed toward the excitation location of the sample, the interrogation beam being focused below the surface of the sample;
• and
• detecting light from the sample, the detected light including a portion of the interrogation beam returning from the sample, wherein the detected light is indicative of the generated radiative and the non-radiative signals,
• wherein the method is used in one or more of the following applications:
• imaging of blood oxygen saturation;
• imaging of tumor hypoxia;
• imaging of wound healing, burn diagnostics, or surgery;
• imaging of microcirculation;
• blood oxygenation parameter imaging;
• estimating blood flow in vessels flowing into and out of a region of tissue;
• imaging of molecularly-specific targets;
• imaging angiogenesis for pre-clinical tumor models;
• clinical imaging of micro-and macro-circulation and pigmented cells;
• imaging of the eye;
• augmenting or replacing fluorescein angiography;
• imaging dermatological lesions;
• imaging melanoma;
• imaging basal cell carcinoma;
• imaging hemangioma;
• imaging psoriasis;
• imaging eczema;
• imaging dermatitis;
• imaging Mohs surgery;
• imaging to verify tumor margin resections;
• imaging peripheral vascular disease;
• imaging diabetic and/or pressure ulcers;
• burn imaging;
• plastic surgery;
• microsurgery;
• imaging of circulating tumor cells;
• imaging melanoma cells;
• imaging lymph node angiogenesis;
• imaging response to photodynamic therapies;
• imaging response to photodynamic therapies having vascular ablative mechanisms;
• imaging response to chemotherapeutics;
• imaging response to anti-angiogenic drugs;
• imaging response to radiotherapy;
• estimating oxygen saturation using multi-wavelength photoacoustic excitation;
• estimating venous oxygen saturation where pulse oximetry cannot be used;
• estimating cerebrovenous oxygen saturation and/or central venous oxygen saturation;
• estimating oxygen flux and/or oxygen consumption;
• imaging vascular beds and depth of invasion in Barrett's esophagus and/or colorectal cancers;
• functional imaging during brain surgery;
• assessment of internal bleeding and/or cauterization verification;
• imaging perfusion sufficiency of organs and/or organ transplants;
• imaging angiogenesis around islet transplants;
• imaging of skin-grafts;
• imaging of tissue scaffolds and/or biomaterials to evaluate vascularization and/or immune rejection;
• imaging to aid microsurgery;
• guidance to avoid cutting blood vessels and/or nerves;
• imaging of contrast agents in clinical or pre-clinical applications;
• identification of sentinel lymph nodes;
• non-or minimally-invasive identification of tumors in lymph nodes;
• non-destructive testing of materials;
• imaging of genetically-encoded reporters, wherein the genetically-encoded reporters include tyrosinase, chromoproteins, and/or fluorescent proteins for pre-clinical or clinical molecular imaging applications;
• imaging actively or passively targeted optically absorbing nanoparticles for molecular imaging;
• imaging of blood clots;
• staging an age of blood clots;
• replacing a catheterization procedure;
• gastroenterological applications;
• single-excitation pulse imaging over an entire field of view;
• imaging of tissue;
• imaging of cells;
• imaging of scattered light from object surfaces;
• imaging of absorption-induced changes of scattered light;
• or
• non-contact imaging of optical absorption.

A photoabsorption remote sensing system for imaging features in a sample, comprising:

• an excitation light source configured to generate signals in the sample at an excitation location, the excitation light source being focused below a surface of the sample;
• an interrogation light source configured to interrogate the sample and directed toward the excitation location of the sample, the interrogation light source being focused below the surface of the sample, wherein a portion of the interrogation light source returning from the sample is indicative of generated signals;
• a detection source configured to detect light from the sample, wherein the detection source is configured to detect a portion of the interrogation light source returning from the sample, the returned portion of the interrogation light source being indicative of generated signals;
• and
• a processor configured to analyze the generated signals as a function of time and determine an image, the image being indicative of features in the sample.

A photoabsorption remote sensing system for imaging features in a sample, comprising:

• an excitation light source configured to generate signals in the sample at an excitation location, the excitation light source being focused below a surface of the sample;
• an interrogation light source configured to interrogate the sample and directed toward the excitation location of the sample, the interrogation light source being focused below the surface of the sample;
• and
• a detection source configured to detect light from the sample, wherein the detection source is configured to detect a portion of the interrogation light source returning from the sample, the returned portion of the interrogation light source being indicative of at least some of the generated signals;
• and
• a processor configured to analyze the generated signals as a function of time and determine an image, the image being indicative of features in the sample.