Other

Quantum Dental Technologies Inc.

University of Toronto

Sunnybrook Research Institute

Andreas Mandelis

Stephen Abrams

Koneswaran S Sivagurunathan

Bahman Lashkari

Sergey A Telenkov

Sergey Telenkov

Jin-Seok Jeon

Anna Matvienko

Adam Hellen

Brian Courtney

Stuart Foster

Chinhua Wang

Nima Tabatabaei

Josh Silvertown

Jose Agustin Garcia

Joshua Daniel Silvertown

Mahendra Munidasa

Sung Soo Choi

Xinxin Guo

Kaicheng Zhang

Pantea Tavakolian

Kiran Kulkarni

Sreekumar Kaiplavil

Alex Vitkin

Ying Fan

Derrick Shaughnessy

Jerias Alves Batista

Jose A Garcia

Jose Agustin Garcia-Hecules

Marek Mieszkowski

Alexander Melnikov

Lena Nicolaides

Jinseok Jeon

Stephen H Abrams

Bonny Wong

Joshua D Silvertown

Systems and methods are disclosed that facilitate the reduction of both radio frequency (RF) noise and photoacoustic artefacts in differential photoacoustic radar imaging through a multi-step electrical and optical domain calibration method. An example two-step calibration method involves reducing RF image noise via an initial calibration step that involves the control of the relative amplitudes and phases of electrical driving modulation waveforms, while a second calibration step involves the differential suppression of photoacoustic artefact signals via tuning, in the optical domain, of the relative intensity the optical beams that are delivered to the sample. Another example embodiment involves the use of the standard deviation of the unwrapped phase that is obtained, after performing frequency-domain cross-correlation and an inverse transform to the time domain, to improve the amplitude signal that is employed to generate a differential photoacoustic radar image.

Systems and methods for performing frequency-domain photoacoustic imaging

Systems and methods are provided for performing thermophotonic imaging using cross-correlation and subsequent time-gated truncation. Photothermal radiation is detected with an infrared camera while exciting a sample with a chirped set of incident optical pulses and time-dependent photothermal signal data is processed using a method that involves performing cross-correlation and subsequent time-gated truncation. The post-cross-correlation truncation method results in depth-resolved images with axial and lateral resolution beyond the well-known thermal-diffusion-length-limited, depth-integrated nature of conventional imaging modalities. An axially resolved photothermal image sequence can be obtained, capable of reconstructing three-dimensional visualizations of photothermal features in wide classes of materials.

Systems and methods for performing enhanced truncated-correlation photothermal coherence tomography

The present disclosure provides systems and methods for imaging based on the generation and use of mismatched coded excitation signals. Cross-correlation properties of the received signal reveal the location and/or timing and/or properties of the source. The use of mismatched signals enables spatial and/or temporal and/or functional encoding of the transmitted signals. In some embodiments, high-speed imaging may be performed by employing mismatched codes for spatial and/or temporal encoding, and by employing a subset of transducer elements as transmitters, and another subset of elements as receivers. Various example embodiments of different types of mismatched codes are provided, including codes that employ multiple frequency chirps, codes that employ concatenated multi-frequency binary phase-coded waveforms, and chirped binary phase-coded waveforms.

Methods for generating multiple mismatched coded excitation signals

Photothermal imaging systems and methods are disclosed that employ truncated-correlation photothermal coherence tomography (TC-PCT). According to the example methods disclosed herein, photothermal radiation is detected with an infrared camera while exciting a sample with the chirped delivery of incident laser pulses (where the pulses have a fixed width), and time-dependent photothermal signal data is obtained from the infrared camera and processed using a time-evolving filtering method employing cross-correlation truncation. The cross-correlation truncation method results in pulse-compression-linewidth-limited depth-resolved images with axial and lateral resolution well beyond the well-known thermal-diffusion-length-limited, depth-integrated nature of conventional thermographic and thermophotonic modalities. As a consequence, an axially resolved layer-by-layer photothermal image sequence can be obtained, capable of reconstructing three-dimensional visualizations (tomograms) of photothermal features in wide classes of materials. Additional embodiments are disclosed in which the aforementioned systems and methods are adapted to photo-acoustic and acousto-thermal imaging.

Systems and methods for performing truncated-correlation photothermal coherence tomography

Systems and methods for improved thermophotonic imaging are provided in which both amplitude and phase image information is obtained with a high signal to noise ratio and depth-resolved capabilities. Image data obtained from an imaging camera is dynamically averaged and subsequently processed to extract amplitude and/or phase image data. The system may be configured for a wide range of imaging modalities, including single frequency modulation (thermophotonic lock-in imaging), Thermal-Wave Radar imaging or Thermophotonic Radar imaging involving chirp modulation, and Binary Phase Coded Modulation. Such imaging modalities may find application in many diverse areas, including non-destructive testing and biomedical diagnostic imaging including the imaging of teeth and monitoring changes in the tooth over time which are due to pathology such as dental caries or erosion.

Systems and methods for thermophotonic dynamic imaging

An apparatus is provided for performing photothermal measurements on a object. The apparatus, which may be provided as a handpiece, houses optical components including a laser, an infrared detector, a dichroic beamsplitter, and focusing and beam directing optics for the delivery of a laser beam to, and the collection of photothermal radiation from, a measured object. Some of the optical components may be provided on an optical bench that is directly attached to a thermally conductive tip portion for the passive heat sinking of internal optical components. The apparatus may further include a sampling optical element and a photodetector for the detection of luminescence, and a camera for obtaining an image of the object during a diagnostic procedure. The apparatus may be employed for the scanning of a tooth to determine an oral health status of the tooth.

Handpiece with integrated optical system for photothermal radiometry and luminescence measurements

A detection system is provided for the measurement of in-vitro dental samples. The detection system includes an optical detection module that is configured for the detection of optical signals that are emitted in response to the absorption of an incident optical beam, and a control and processing unit that is configured for processing the detected optical signals and generating an image. The system also includes a sample holder may be removed and subsequently replaced without requiring recalibration of the system. In some embodiments, the optical detection module is configured for combined measurement of photothermal radiation and luminescence in response to the absorption of the incident optical beam.

Apparatus for in-vitro imaging and analysis of dental samples

Systems and methods of frequency-domain photoacoustic imaging are provided utilizing an ultrasonic phased array probe and intensity modulated optical excitation with coding to improve signal-to-noise ratio. Embodiments employ frequency-domain photoacoustic imaging methodologies such as the photoacoustic radar, coupled with a multi-element ultrasonic sensor array to deliver spatially-resolved correlation images of photoacoustic sources, which may be employed to image optical heterogeneities within tissue-like scattering media.

Systems and methods for frequency-domain photoacoustic phased array imaging

Methods are provided for producing optical carrierographic images of a semiconductor sample. Focused and spatially overlapped optical beams excite carriers across within the semiconductor sample, where the optical beams are modulated such that a beat frequency is substantially less than either modulation frequency. An infrared detector detects infrared radiation emitted from the semiconductor sample in response to absorption of the optical beams, thereby obtaining a plurality of carrierographic signals at different points in time during at least one beat period, which are processed with a lock-in amplifier, with a reference signal at the beat frequency, to obtain an amplitude signal and a phase signal. Carrierographic lock-in images of the sample are obtained in a scanning configuration, or in an imaging format using an imaging detector. The images carry quantitative information about recombination lifetimes in substrate Si wafers and electrical parameters in solar cells, namely photogeneration current density, diode saturation current density, ideality factor, and maximum power photovoltage.

Method and apparatus for performing heterodyne lock-in imaging and quantitative non-contact measurements of electrical properties

Methods are provided for the detection of an analyte in a sample using wavelength modulated differential photothermal radiometry with enhanced sensitivity. A wavelength modulated differential photothermal radiometry system, comprising two optical modulated beams, where each beam experiences different absorption by the analyte, is calibrated by controlling the relative phase difference between the modulated beams so that individual photothermal signals corresponding to each modulated beam are 180&#xb0; out of phase, corresponding to peak sensitivity to analyte concentration. The system may be further calibrated by varying the relative intensities of the two modulated beams and measuring standards containing known analyte concentration in order to determine an optimal relative intensity for a given concentration range of interest.

Method of performing wavelength modulated differential laser photothermal radiometry with high sensitivity

There is provided a glucose monitoring method and apparatus based on the principle of Wavelength-Modulated Differential Laser Photothermal Radiometry (WM-DPTR). Two intensity modulated laser beams operating in tandem at specific mid-infrared (IR) wavelengths and current-modulated synchronously by two electrical waveforms 180 degrees out-of-phase, are used to interrogate the tissue surface. The laser wavelengths are selected to absorb in the mid infrared range (8.5-10.5 &#x3bc;m) where the glucose spectrum exhibits a discrete absorption band. The differential thermal-wave signal generated by the tissue sample through modulated absorption between two specific wavelengths within the band (for example, the peak at 9.6 and the nearest baseline at 10.5 &#x3bc;m) lead to minute changes in sample temperature and to non-equilibrium blackbody radiation emission. This modulated emission is measured with a broadband infrared detector. The detector is coupled to a lock-in amplifier for signal demodulation. Any glucose concentration increases will be registered as differential photothermal signals above the fully suppressed signal baseline due to increased absorption at the probed peak or near-peak of the band at 9.6 &#x3bc;m at the selected wavelength modulation frequency. The emphasis is on the ability to monitor blood glucose levels in diabetic patients in a non-invasive, non-contacting manner with differential signal generation methods for real-time baseline corrections, a crucial feature toward precise and universal calibration (independent of person-to-person contact, skin, temperature or IR-emission variations) in order to offer accurate absolute glucose concentration readings.

System and method for non-invasive photothermal radiometric measurement

A method of oral health risk assessment is provided in which diagnostic data from an oral health detection device and patient risk factor data is processed to provide a integrated risk measure relating to a patient's dental health. The patient risk factor data preferably includes risk factor data such as pathological risk factors, protective risk factors, historical factors, self care factors, behavioral factors, and extrinsic factors. The integrated risk assessment and patient data is preferably provided to a remote server for access by various authorized stakeholders.

Method of assessing oral health risk

There is provided a high-spatial-resolution dynamic diagnostic instrument which can provide simultaneous measurements of laser-induced frequency-domain infrared photothermal radiometric and alternating-current (ac) modulated luminescence signals from defects, demineralization, remineralization and caries in teeth intraorally. The emphasis is on the abilities of this instrument to approach important problems such as the detection, diagnosis and ongoing monitoring of carious lesions and or defects on the occlusal pits and fissures, smooth surfaces and interproximal areas between teeth which normally go undetected by x-ray radiographs or visual examination. The instrument is also able to detect early areas of demineralized tooth and or areas of remineralized tooth as well as defects along the margins of restorations. This capability of inspecting a local spot can be extended to a modulated imaging of sub-surface of target tooth by using a multi-array infrared camera. Two configurations of the instrument are presented.

Method and apparatus using infrared photothermal radiometry (PTR) and modulated laser luminescence (LUM) for diagnostics of defects in teeth

Non-invasive biothermophotonic sensor for blood glucose monitoring

A method and apparatus for biomedical subsurface imaging and measurement of thickness, elastic and optical properties of industrial and biomedical materials based on laser Photo-Thermo-Acoustic (PTA) frequency-swept heterodyne depth profilometry, In particular, the invention relates to biomedical imaging and measure of tissue and tumour thickness, L, speed of sound, c, acoustic attenuation coefficient, &#x3b3;, optical absorption coefficient, &#x3bc;, and optical scattering coefficient, &#x3bc;. The method and apparatus involves providing for a sample of the material to be characterized; irradiating the material for a selected period of time with an excitation waveform from a modulated optical excitation source wherein a photo-thermo-acoustic emission is responsively emitted from said solid; detecting said emitted photo-thermo-acoustic emission; processing the electronic signal to convert the frequency-domain signal into time-domain and perform depth profilometric imaging and determining thermoelastic and optical properties of the material sample.

Growing community of inventors

Scarborough, Canada

Andreas Mandelis