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Surgical margin analysis (SMA) is an essential procedure in a cancer resection surgery to judge whether all cancer cells are excised from a patient’s body. A positive surgical margin, which means there are still residual cancer cells in the body, could lead to a high recurrence rate. The standard procedure of histological analysis for SMA requires several steps before imaging, including tissue fixation, embedding, sectioning, and staining, which are time-consuming and laborious. Patients are required to undergo second surgeries if a positive surgical margin is found in this post-operative analysis. Therefore, there is a pressing need for a reliable intraoperative tool to eliminate second surgeries. Ultraviolet photoacoustic microscopy (UV-PAM), which does not require any sample processing, has recently been developed as a potential imaging tool for intraoperative SMA. However, the imaging speed of UV-PAM should be improved to promote it as a practical intraoperative diagnostic tool. In this thesis, we developed a galvanometer mirror-based UV-PAM (GM-UV-PAM) system for high-speed label-free histology-like imaging. By implementing a one-dimension (1D) galvanometer mirror into our UV-PAM system with a high repetition rate (55 kHz) UV laser, the proposed GM-UV-PAM system can generate subcellular images in less than 15 min over an area of 5 mm × 5 mm, with a lateral resolution of ~1.0 μm. To demonstrate our GM-UV-PAM system can provide histological analysis for SMA, mouse brain slices with different tissue processing protocols were imaged. The results of imaging thin mouse brain slices show that our GM-UV-PAM images can provide histological information that is consistent with that in standard histological images. For thick tissue sample imaging, the results illustrate that our GM-UV-PAM system can generate high-quality histology-like images for fresh tissue at high speed, which is not achievable in traditional histology.

In recent years, the photoacoustic effects in solid materials, induced by the absorption of intensity-modulated laser radiation, were used as a versatile tool for optical and thermal characterization of a variety of samples. In our work, by using the photoacoustic detection technique, the measurement was first carried out to obtain the thermal diffusivity values of commercial papers (i.e. white paper, drawing paper, filtering paper, wrapping paper, fax paper and press paper), sago starch, chitosan and the blends of sago starch with chitosan. All the measurements for these samples were carried out at room temperature. It was based upon the measurement of the photoacoustic signal as a function of the modulation frequency in the region where the thermal diffusion length equals to the sample thickness.

In recent years, the photoacoustic effects in solid materials, induced by the absorption of intensity-modulated laser radiation, were used as a versatile tool for optical and thermal characterization of a variety of samples. In our work, by using the photoacoustic detection technique, the measurement was first carried out to obtain the thermal diffusivity values of commercial papers (i.e. white paper, drawing paper, filtering paper, wrapping paper, fax paper and press paper), sago starch, chitosan and the blends of sago starch with chitosan. All the measurements for these samples were carried out at room temperature. It was based upon the measurement of the photoacoustic signal as a function of the modulation frequency in the region where the thermal diffusion length equals to the sample thickness.

The capability of photoacoustic technique in thermal diffusivity measurement has attracted a lot of interest lately. In the experiment, the open photoacoustic cell (OPC) technique was applied for thermal diffusivity measurement on solid materials such as metal, superconductors and soft ferrites. The photoacoustic signal amplitude was captured as a function of modulated frequency and the characteristic frequency, fc, of each sample is computed. Thermal diffusivity was calculated based on the!c and the sample thickness. The way that thermal diffusivity value behaves towards the change of dopant concentration were then investigated. Generally, the thermal diffusivity value measured were between 0.19 to 0.99 cm²/s. The second part of the work concentrated on liquid materials. By applying the basic theoretical approach and redesigning the OPC sample cell, the thermal effusivity value of liquid samples were able to be determined. The samples chosen were distilled water, engine oil, lubricant, edible oil and creamy consumer products. The measured value was in a good agreement with the reported values previously published. The technique was feasible in obtaining thermal effusivity ranged from 0.042 to 0.l59 Wsl/2/(cm²˚C). Thirdly, for liquid samples with low boiling point such as acetone, methanol and ethanol solvents, the PA technique was used to monitor its evaporation time. The sample of interest was placed in a 13.57 mm³ container heated by a 30 mW He-Ne laser beam. As expected, the evaporation time were found to be inversely proportional to the respective boiling points. The fourth part of the work focused on investigation on the protonation process in polyanilines, a kind of conducting polymer. The photoacoustic spectroscopy was obtained where the optical absorption spectrum was plotted against photon energy. Other then this, the Fourier Transform Infrared (FTIR) spectra, thermal diffusivity and scanning electron microscope (SEM) diagram were also examined. Generally

The capability of photoacoustic technique in thermal diffusivity measurement has attracted a lot of interest lately. In the experiment, the open photoacoustic cell (OPC) technique was applied for thermal diffusivity measurement on solid materials such as metal, superconductors and soft ferrites. The photoacoustic signal amplitude was captured as a function of modulated frequency and the characteristic frequency, fc, of each sample is computed. Thermal diffusivity was calculated based on the!c and the sample thickness. The way that thermal diffusivity value behaves towards the change of dopant concentration were then investigated. Generally, the thermal diffusivity value measured were between 0.19 to 0.99 cm²/s. The second part of the work concentrated on liquid materials. By applying the basic theoretical approach and redesigning the OPC sample cell, the thermal effusivity value of liquid samples were able to be determined. The samples chosen were distilled water, engine oil, lubricant, edible oil and creamy consumer products. The measured value was in a good agreement with the reported values previously published. The technique was feasible in obtaining thermal effusivity ranged from 0.042 to 0.l59 Wsl/2/(cm²˚C). Thirdly, for liquid samples with low boiling point such as acetone, methanol and ethanol solvents, the PA technique was used to monitor its evaporation time. The sample of interest was placed in a 13.57 mm³ container heated by a 30 mW He-Ne laser beam. As expected, the evaporation time were found to be inversely proportional to the respective boiling points. The fourth part of the work focused on investigation on the protonation process in polyanilines, a kind of conducting polymer. The photoacoustic spectroscopy was obtained where the optical absorption spectrum was plotted against photon energy. Other then this, the Fourier Transform Infrared (FTIR) spectra, thermal diffusivity and scanning electron microscope (SEM) diagram were also examined. Generally

The open photoacoustic cell (OPC) technique was used for measuring thermal diffusivity of solid samples. It is based upon the measurement of the photoacoustic signal as a function of the modulation frequency in the region where the thermal diffusion length equals to the-sample thickness. The measurements were carried out at room temperature for samples metal, alloy, semiconductor, polymer and superconductor. The measured thermal diffusivity values for metal, semiconductor and polymer samples are in good agreement with the values reported previously by other researchers. The thermal diffusivity values of the AgxAu1-x alloys decrease from 1.48 cm2/s (pure Ag) to a minimum value at around x = 0.70 before increasing towards the value of 1.28 cm2/s (pure Au). In AuxCu(l00-x)07Ag(l00-x)O.3 alloy system, the thermal diffusivity values decrease with the increasing of the weight fraction x and reaching a minimum at around x = 90 composition. Then, the thermal diffusivity values tend to increase to the value of 1.28 cm2/s for the pure Au metal. For superconductor samples in the normal state, the measured thermal diffusivity decreases with the increase of Zn content in the BbPbo.6Sr2Ca2-xZnxCu30o system, However, the thermal diffusivity values increase with the increasing of Ba dopant in the Bi2Pbo.6Sr2Ca2-xBaxCu30o system. The OPC detection was also used to monitor the evaporation time of the liquid samples. The evaporation time for 10.60 mm3 of acetone, chloroform, methanol and ethanol samples were recorded as 236.7s, 578.8s, 436.2s and 869.2s respectively. The results also show that the liquid evaporation time is inversely proportional to the laser power. The laser beam power in the range of (2-16) m W was monitored by using OPC, closed photoacoustic cell (CPC) and piezoelectric (PZT) detections. In each case, the photoacoustic (PA) signals were found to be linear up to the laser power of 16 m W. In comparison, the power meter responsivity for CPC detection always higher th

The open photoacoustic cell (OPC) technique was used for measuring thermal diffusivity of solid samples. It is based upon the measurement of the photoacoustic signal as a function of the modulation frequency in the region where the thermal diffusion length equals to the-sample thickness. The measurements were carried out at room temperature for samples metal, alloy, semiconductor, polymer and superconductor. The measured thermal diffusivity values for metal, semiconductor and polymer samples are in good agreement with the values reported previously by other researchers. The thermal diffusivity values of the AgxAu1-x alloys decrease from 1.48 cm2/s (pure Ag) to a minimum value at around x = 0.70 before increasing towards the value of 1.28 cm2/s (pure Au). In AuxCu(l00-x)07Ag(l00-x)O.3 alloy system, the thermal diffusivity values decrease with the increasing of the weight fraction x and reaching a minimum at around x = 90 composition. Then, the thermal diffusivity values tend to increase to the value of 1.28 cm2/s for the pure Au metal. For superconductor samples in the normal state, the measured thermal diffusivity decreases with the increase of Zn content in the BbPbo.6Sr2Ca2-xZnxCu30o system, However, the thermal diffusivity values increase with the increasing of Ba dopant in the Bi2Pbo.6Sr2Ca2-xBaxCu30o system. The OPC detection was also used to monitor the evaporation time of the liquid samples. The evaporation time for 10.60 mm3 of acetone, chloroform, methanol and ethanol samples were recorded as 236.7s, 578.8s, 436.2s and 869.2s respectively. The results also show that the liquid evaporation time is inversely proportional to the laser power. The laser beam power in the range of (2-16) m W was monitored by using OPC, closed photoacoustic cell (CPC) and piezoelectric (PZT) detections. In each case, the photoacoustic (PA) signals were found to be linear up to the laser power of 16 m W. In comparison, the power meter responsivity for CPC detection always higher th

The technique of optoacoustic spectroscopy on the use of modulated or pulsed light beams to produce, directly or indirectly, acoustic waves or pulses in a gaseous or condensed sample, as the excitation beam is scanned in wavelength, an excitation spectrum, called optoacoustic (or photoacoustic) spectrum, is produced. This paper reviews some of the theories and experiments in this field.

We discuss the measurement of small optical surface absorption coefficients. A demonstration experiment was performed using a metallurgical strain gauge to measure 488 nm absorption on the surface of a glass plate. A strain of 10 to the minus 8th power resulted from absorption of 0.3 watts. The results are interpreted and the sensitivity of a proposed fiber optic strain gauge is discussed.

The present invention relates to a novel fiber optic spectrophone device for the measurement of the optoacoustic absorption coefficients of gases under irradiation by laser sources. A gas sample, contained within a spectrophone, is irradiated with a modulated beam of radiant energy which produces an acoustic pressure wave within the gas sample at the modulation frequency having an intensity related to the degree of absorption of the beam by the gas sample. The spectrophone includes a plurality of turns of optical fiber wound about a compliant cylinder. The acoustic pressure wave is coupled by the compliant cylinder to produce changes in the optical length of the fiber in response to the intensity of the pressure wave. The changes in length of the fiber are detected by an all-fiber Mach-Zehnder interferometer which produces an output representative of the pressure wave. The interferometer includes a compensation system for compensating for the effects of environmental perturbations on the system.

Lau Shing-tat., Chinese title, Bibliography: leaves 129-130, Thesis (M.Phil.)--Chinese University of Hong Kong, 1983, http://library.cuhk.edu.hk/record=b5885386, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Thesis (M.S.)--Florida Atlantic University, 1986., Summary: This thesis begins with a general outline of the applications of photoacoustic effects belonging to the more general area of photothermal measurement techniques. Next comes a discussion of the one-dimensional theory that describes the photoacoustic effect. Then it describes the experiments performed using a photoacoustic cell with an adjustable cell length and the conventional front window replaced with an optically opaque and thermally thin disk sample. For the different samples used, most of the cell response was found to be linear with the laser beam power up to 3.5 watts. Finally, the cell's performance as a power meter is analyzed and recommendations made for future investigations., Charles E. Schmidt College of Science, Collection: FAU Electronic Theses and Dissertations Collection

Thesis (M.S.)--Florida Atlantic University, 1983., Summary: The thesis first discusses the history of the photoacoustic effect, concentrating on the early history and recent investigations of the effect in solids. It then develops the theoretical description of a cell with the front window replaced with a thermally-conductive opaque membrane. The dissertation then describes the experiments performed using this and other cell designs and analyzes the results to show that the data are consistent with the theory. Finally, the system performance as a photodetector is analyzed and recommendations for improvements and future investigations made. The Appendix describes the conventional (Rosencwaig-Gersho) theory.