In order to accurately measure the glucose concentration, the photoacoustic spectroscopy combined with the scanning position method was used in this paper. Meanwhile, a kind of custom-built photoacoustic detection system was established. In this system, a 532nm pumped OPO pulsed laser was used as the excitation source, and a non-focused ultrasonic detector was used to capture the photoacoustic signals of phantom and glucose. To improve the measurement accuracy of glucose by using the photoacoustic spectroscopy, a scanning sub-system was established to accurately locate the position of the simulated vessel. In the experiments, to simulate the bio-tissue and the blood vessel in human body, a specimen made of agar block with a carbon bar and a silicon gel pipe was prepared to verify the availability and feasibility of the established photoacoustic detection system. According to the obtained photoacoustic peak-to-peak values of the specimen by scanning method, the position of the carbon bar and the silicon gel pipe in the specimen can be located. Then, to test the photoacoustic detection of glucose in the silicon gel pipe, a cycling sub-system was used to simulate the blood flow in the blood vessel. Based on the located position of the silica gel pipe, the focused laser spot was shifted and accurately irradiated into the silica gel pipe to induce the photoacoustic signals of glucose. By mean of the photoacoustic system, several different concentrations of glucose solutions were test, and the time-resolved photoacoustic signals and peak-to-peak values of glucose are all obtained. The prediction model of glucose concentration was established by using the linear fitting method. At the same time, the predicted result was compared with that of the glucose in the agar specimen. Results show that the novel photoacoustic detection of glucose is available. The correction coefficient of the glucose concentration prediction was improved by using the photoacoustic spectroscopy combined with the scanning position method.
In this study, the photoacoustic detection system was established based on the Q switched Nd: YAG 532nm pumped optical parametric oscillator pulsed laser and the ultrasonic detector. Based on the established photoacoustic detection system, the effects of pulsed laser on the photoacoustic detection of glucose aqueous solutions were experimentally studied. The photoacoustic peak-to-peak values of glucose and pure water were obtained at different output energy of pulsed laser and at the wavelengths from 1300nm to 2200nm. Experimental results show that the photoacoustic peak-to-peak values of glucose linearly increase with the increasing of the output energy of pulsed laser. The photoacoustic peak-to-peak values were compensated because the output energy of pulsed laser exponentially decreased with the increasing of the wavelengths of pulsed laser. The characteristic wavelengths of glucose were determined according to the difference spectral between the compensated photoacoustic peak-to-peak values of glucose aqueous solution and pure water.
Optical-resolution photoacoustic microscopy (OR-PAM) is an emerging technique for microvasculature imaging at high spatial resolution and contrast. In this work, we present a practical visible laser-diode-based OR-PAM (LD-OR-PAM) prototype for vasculature imaging, which has the desirable properties of being portable, low-cost, and label-free. The prototype employs a 300 mW pulsed laser diode in a 3.8 mm diameter package, emitting 174 ns pulses at 405 ± 5 nm wavelength and a pulse energy of 52 nJ. An aspheric objective with a numerical aperture of 0.60 is used to achieve microscope optical illumination. The laser diode excitation has a compact size of 4.5 × 1.8 × 1.8 cm3 assembled with a cooling block. The lateral resolution was tested to be 0.95 μm on ~7 μm carbon fibers. The subcutaneous microvasculature on a mouse back was label-free imaged ex vivo, which demonstrates the potential of the LD-OR-PAM prototype for in vivo imaging skin chromosphores such as hemoglobin. Our ultimate aim is to provide a practical and affordable OR-PAM system as a routine instrument for standard clinical applications.
In this paper, a noninvasive photoacoustic measurement setup was established to simple simulate the glucose concentration measurement. The PPA signal excited by a pulsed tunable wavelength laser can be used to determine the glucose concentration in solution. By building the multiple linear regression (MLR) model for the peak valves of the PPA signal at five characteristic absorption wavelengths, the relative error of prediction is less than 20% and the absolute error is less than 33mg/dL.
In this paper, the stray light for an optical splitting system of micro biochemical analyzer is ray tracing by using software FRED and actually measured respectively. The generation and propagation of stray light is simulated and the measures of restraining stray light, such as setting baffle structure, coating critical surface and optimizing light source path are put forward. The results of experiment for improved system show that the stray light coefficient is reduced from 4.6% to 1.2%.
Solid-state laser systems, such as traditional Nd:YAG-based lasers, are commonly used for noninvasive biomedical photoacoustics with nanosecond pulse duration and millijoule pulse energy. However, such lasers are both bulky and expensive for use as a handy tool for clinical applications. As an alternative, a semiconductor light source has the advantages of being compact, inexpensive, and robust. In addition, the main drawback of low peak output power may make it exactly suitable for the imaging modalities, which require relatively low pulse energies, such as acoustic- and optical-resolution photoacoustic microscopy (AR/OR-PAM). We propose a cost-efficient OR-PAM for two-dimensional/three-dimensional (2-D/3-D) biological imaging based on a pulsed near-infrared laser diode. By raster scanning, typical 2-D photoacoustic images were obtained at different scales, and 3-D surface renderings were clearly reconstructed with a marching cubes algorithm. This initial study would promote the production of portable OR-PAM technology for clinical and biomedical applications.
In this paper, a POF connector based on a two ball lens system is researched. To analysis the coupling efficiency of the
connector, a numerical model was established using ray tracing method and four defects of transverse offset, longitudinal
offset, angular misalignment and gap between two ball lenses in the coupling system are calculated. The calculation
results show that the POF connector based on a two ball lens system can improve the coupling efficiency between two
fibers and has good tolerance to the connection defects of transverse, longitudinal and angular misalignments.
A portable near-infrared photoacoustic scanning imaging system has been developed with a single pulsed laser diode,
which was integrated with an optical lens system to straightforward boost the laser energy density for photoacoustic
generation. The 905 nm laser diode provides a maximum energy output of 14 μJ within 100 ns pulse duration, and the pulse
repetition frequency rate is 0.8 KHz. As a possible alternative light source, the preliminary 2D photoacoustic results
primely correspond with the test phantoms of umbonate extravasated gore and knotted blood vessel network. The
photoacoustic SNR can reach 20.6±1.2 dB while signal averaging reduces to 128 pulses from thousands to tens of
thousands times, and the signal acquisition time accelerates to less than 0.2 s in each A-scan, especially the volume of the
total radiation source is only 10 × 3 × 3 cm3. It demonstrated that the pulsed semiconductor laser could be a candidate of
photoacoustic equipment for daily clinical application.
With the rapid development of the society and living standard, the water resources have been polluted more and more
seriously, which is threatening the health of people and producing of the industry and agriculture. To protect the
sustainable water resource, the monitoring of the water quality became an urgent task. There are some methods used to
monitor the water quality, including the liquid chromatograph(LC), electrolysis method, electrochemical method,
colorimetry method, atomic absorption spectrometric method, etc. But some drawbacks are existed in these methods. So,
a fluorescence spectrophotometry method is adopted into this paper. And a novel water quality monitor(WQM) is
designed. Meanwhile, in order to improve the spectral resolution and prevision, an improved spectrophotometer(SPM)
based on holography concave (HC)grating is designed. In addition, the linear CCD with combined data acquisition
(DAQ) card is used as the spectral detection system and virtual instrument(VI) technology based on LabVIEW is used to
control the spectral acquisition and analysis. Experimental results show that the performances of the novel SPM for
WQM are improved, its resolution can reach 2nm, the stray-light is less and the checking prevision of this WQM is
higher than others. Therefore, the novel SPM for WQM has the potential value in the water quality monitoring and
biochemical application.
The ultrasonic imaging, X-mammography, CT imaging and MRI can be applied into the breast cancer diagnosis(BCD).
But some factors such as the spatial resolution, contrast and
price-performance ratio (PPR) limit their applications. So, a
novel BCD technology, that is, multi-spectral imaging is adopted into this paper. It can get more information of the
breast tumor and higher identity because it combines the advantages of the spectroscopy and the imaging technology.
And in this paper, the multi-spectral light source induced the breast cancer imaging detector(BCID) is designed, the
spectrum can cover from the UV to NIR. Meanwhile, a custom-built multi-spectral imaging spectrometer (MSIS) is also
developed. And, in order to overcome the stray-light of the
light-route system and improve the resolution and
light-passing efficiency of the system, the novel volume holography transmissive (VHT) grating instead of the plane or
concave grating is used as the diffraction grating in this MSIS. Experimental result show that the novel BCD technology
is feasible, it can offer not only the spectral information but also the image of the tumor. The spectrum resolution of the
MSIS for BCID based on VHT grating can reach 2nm. Compared with the others, this BCID has more compact structure,
faster speed, higher PPR and higher resolution and accuracy. Therefore, this BCID has the potential value in the field of
the BCD.
Tongue diagnosis (TD) is an important diagnostic methods in the traditional Chinese medicine (TCM). According to the
viewpoint of TCM, the changes of the tongue coating (TC) can reflect the pathological state of the patient. And the
nature or severity of diseasec can be determined by observing the TC. Over the years, TD is mostly depended on the
subjective experience of the Chinese physician. And the diagnostic results will be impacted by.some factors, e.g. the
different light sources or environmental brightness. Recently years, the method of digital image processing has been used
into the TD. But its application is limited by the complicated algorithm, time-consuming and big error, etc. Therefore, a
novel tongue coating analyzer(TCA) is designed in this paper. Meanwhile, a novel spectrometer for TCA based on the
volume holography transmissive (VHT) grating is developed. In this spectrometer, since the VHT grating doesn't
produce the stray-light due to the absence of the grooves of classical surface-embossed gratings, the VHT grating is used
as the diffraction grating instead of the classical plane or concave grating. Experimental results show that the
performances of the spectrometer for TCA have been improved by using the VHT grating, optimizing the light-path
structure and software algorithm, etc. Compared with the others, this spectrometer for TCA has many advantages, such
as, less diffraction, wider spectrum range, higher efficiency and resolution, etc. The spectrum range of the spectrometer
for TCA can reach 300-1000nm, its resolution can reach 1nm and the optical density is larger than 3.
The tongue coating diagnosis is an important part in tongue diagnosis of traditional Chinese medicine (TCM).The change
of the thickness and color of the tongue coating can reflect the pathological state for the patient. By observing the tongue
coating, a Chinese doctor can determine the nature or severity of disease. Because some limitations existed in the tongue
diagnosis method of TCM and the method based on the digital image processing, a novel tongue coating analyzer(TCA)
based on the concave grating monochrometer and virtual instrument is developed in this paper. This analyzer consists of
the light source system, check cavity, optical fiber probe, concave grating monochrometer, spectrum detector system
based on CCD and data acquisition (DAQ) card, signal processing circuit system, computer and data analysis software
based on LabVIEW, etc. Experimental results show that the novel TCA's spectral range can reach 300-1000 nm, its
wavelength resolution can reach 1nm, and this TCA uses the back-split-light technology and multi-channel parallel
analysis. Compared with the TCA based on the image processing technology, this TCA has many advantages, such as,
compact volume, simpler algorithm, faster processing speed, higher accuracy, cheaper cost and real-time handle data and
display the result, etc. Therefore, it has the greatly potential values in the fields of the tongue coating diagnosis for TCM.
As a new field of combined ultrasound/photoacoustic imaging in biomedical photonics research, we present and
demonstrate a high-speed laser photoacoustic imaging system combined with digital ultrasound imaging platform. In the
prototype system, a new B-mode digital ultrasonic imaging system is modified as the hardware platform with 384
vertical transducer elements. The centre resonance frequency of the piezoelectric transducer is 5.0 MHz with greater than
70% pulse-echo -6dB fractional bandwidth. The modular instrument of PCI-6541 is used as the hardware control centre
of the testing system, which features 32 high-speed channels to build low-skew and multi-channel system. The digital
photoacoustic data is transported into computer for subsequent reconstruction at 25 MHz clock frequency. Meantime, the
software system for controlling and analyzing is correspondingly explored with LabVIEW language on virtual
instrument platform. In the breast tissue experiment, the reconstructed image agrees well with the original sample, and
the spatial resolution of the system can reach 0.2 mm with multi-element synthetic aperture focusing technique.
Therefore, the system and method may have a significant value in improving early detecting level of cancer in the breast
and other organs.
KEYWORDS: Holograms, Holography, Digital holography, 3D image reconstruction, Computer simulations, Digital imaging, Reconstruction algorithms, Computer security, Information security, Data storage
In this paper, a new method of 3D data information encryption with virtual holography is proposed. The data information is encoded in the form of 3-D data cubes. A cube can be described as an assembly of slices which are parallel planes along the coordinates at an interval of d. The dot on the slices of the 3-D data cube represents a bit, and the bright one means "1", while the dark one means "0". The hologram of the 3-D cube is generated in computer with virtual holography, and the hologram can be transformed into a secondary hologram with virtual holography technique again. Thus the 3-D data cube can be encrypted in the form of the secondary hologram, in which the parameters are used as the keys, such as the wavelength of light, the propagation distance of wave, the geometrical parameters of the data cube and so on. Only all of the parameters keys are provided correctly, the data information can be retrieved entirely. Numerical experiments are performed to illustrate the ability to encrypt the 3-D data information with virtual holograph technique. The computer simulation results show, that the data information can obtain higher security and certain robustness with this method.
A near-infrared photoacoustic glucose monitoring system, which is integrated dual-wavelength pulsed laser diode
excitation with eight-element planar annular array detection technique, is designed and fabricated during this study. It
has the characteristics of nonivasive, inexpensive, portable, accurate location, and high signal-to-noise ratio. In the
system, the exciting source is based on two laser diodes with wavelengths of 905 nm and 1550 nm, respectively, with
optical pulse energy of 20 μJ and 6 μJ. The laser beam is optically focused and jointly projected to a confocal point with
a diameter of 0.7 mm approximately. A 7.5 MHz 8-element annular array transducer with a hollow structure is machined
to capture photoacoustic signal in backward mode. The captured signals excitated from blood glucose are processed with
a synthetic focusing algorithm to obtain high signal-to-noise ratio and accurate location over a range of axial detection
depth. The custom-made transducer with equal area elements is coaxially collimated with the laser source to improve the
photoacoustic excite/receive efficiency. In the paper, we introduce the photoacoustic theory, receive/process technique,
and design method of the portable noninvasive photoacoustic glucose monitoring system, which can potentially be
developed as a powerful diagnosis and treatment tool for diabetes mellitus.
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