Propagation of polarized light in turbid media such as bio-tissue has attracted significant recent interest because of its
promising applications in noninvasive optical diagnosis and imaging. In this paper Monte Carlo algorithm and
Stokes-Mueller formalism were used to simulate the propagation behavior of polarized light in turbid media and discuss
the backscattered polarization patterns in a layered structure. The two dimensional (2D) distributions of backscattered
Stokes vectors were calculated. Using user-defined functions, integrated Stokes vectors were calculated and analyzed
quantificationally. Results suggest that each optical property parameter, such as scattering, absorption and structure layer,
has dissimilar effects on backscattered polarization patterns. Scattering produce a spatial re-distribution of light, while
absorption only causes a uniform decrease in intensity. Both can be easily differentiated by backscattered polarization
patterns. Backscattered polarization patterns from a two-layer model with thin surface layer were also calculated,
integrated Stokes vector represent disparate alternant rule for upper and lower layer, which suggest possibilities for
discriminating subtle epidermal structure. All these results together indicate that discriminate optical properties in turbid
media with layered structure using backscattered polarization patterns is feasible.
Laser irradiation is the most acceptable therapy for PWS patient at present time. Its efficacy is highly dependent on the
energy deposition rules in skin. To achieve optimal PWS treatment parameters a better understanding of light
propagation in PWS skin is indispensable. Traditional Monte Carlo simulations using simple geometries such as planar
layer tissue model can not provide energy deposition in the skin with enlarged blood vessels. In this paper the structure
of normal skin and the pathological character of PWS skin was analyzed in detail and the true structure were simplified
into a hybrid layered mathematical model to character two most important aspects of PWS skin: layered structure and
overabundant dermal vessels. The basic laser-tissue interaction mechanisms in skin were investigated and the optical
parameters of PWS skin tissue at the therapeutic wavelength. Monte Carlo (MC) based techniques were choused to
calculate the energy deposition in the skin. Results can be used in choosing optical dosage. Further simulations can be
used to predict optimal laser parameters to achieve high-efficacy laser treatment of PWS.
Optical systems have been extensively studied for target recognition in a turbid medium because of its promising
applications in many fields such as driver assistant system. Several recent studies have demonstrated that relevant
information of the turbid medium including the hidden object in the medium can be derived by analyzing the polarization
state of diffusely backscattered light of the sample. In this paper Stokes/Mueller formula was introduced to investigate
polarized light transportation in a turbid medium such as atmosphere; Mie scattering theory was applied to calculate the
scattering property of polarized light; Monte Carlo method was used to compute backscattered polarization patterns from
a turbid medium containing hidden object. Results showed that the backscattered polarization patterns are strongly
influenced by optical parameters of the medium. The two-dimensional distribution of degree of polarization (DOP)
calculated from backscattered Mueller matrix can well discriminate different objects within limited distance. For
applications in driver assistant system, the effective recognition distance in a foggy weather was also calculated; and
results could be several times of visibility distance.
A Monte Carlo algorithm to simulate the propagation of polarized light was used and the backscattered Mueller matrices
were calculated for various scattering and absorption coefficients and layered structures. Results show that scattering
produce a spatial re-distribution of light, while absorption only causes a uniform decrease in intensity. The major
contribution to backscattered Mueller matrix comes from weakly scattered photons. As scattering enhances the majority
of these photons exit from around the centre. result in image intensity increase around the centre and decrease at the edge.
For absorption strengthen only uniform intensity weakening was observed. Both can be easily differentiated by Mueller
matrix distribution patterns. A two-layer niodel with thin surface layer was also calculated, Mueller matrix represent
disparate alternant rule for upper and lower layer, which suggest possibilities for discriminating subtle epidennal
structure. All these results together indicate that discriminate optical properties in turbid media using backscattered
Mueller matrix is feasible.
The technology of time-resolved diffuse optical spectroscopy to determine optical parameters of biological tissues is reviewed in this paper. The theoretical model and some the development conditions are also presented. As an example, a Monte Carlo algorithm was developed to a two-layered tissue. Based on the numerical simulation, the structure information including the optical properties of the tissue can be obtained. In addition, the prospect of time-resolved diffuse optical spectroscopy technology is commented based on our opinion.
The current therapy methods for prostatitis, and its advantages and disadvantages were discussed in this paper. Two kinds of noninvasive therapy method were presented based on the combination of diode laser technique with traditional Chinese acupuncture and the interaction between low energy laser and biotissue. Firstly, dual-wavelength diode laser with the wavelength of 650nm and 810nm, respectively, were used to irradiate the acupoints. Diode laser with the wavelength of 650nm has remarkable biological stimulation effect, while 8lOnm diode laser mainly has thermal effect. Secondly, a low frequency pulse electromagnetic field is also applied when the targets are irradiated by the diode laser in the application of laser-electromagnetism therapy. Finally, the laser and electromagnetism parameters, as well as therapy methods and instrumental design are also presented in detail.
Using the Y type fiber, high efficiency fiber coupler and A1GaInP diode laser has developed a new diode laser therapy apparatus with the wavelength of 650nm. The output laser power from the fiber of the apparatus can reach more than 100mW. The fiber localizer of the apparatus is easy for orientation during the therapy and the output laser power is very stable and reliable. The apparatus has been widely used in about 20 hospitals, and has successfully cured more than 50,000 patients who suffered from various diseases, which mainly including cervical spondylosis, traumatic infection, skin bruise, sudden deafness, tympanitis, tinnitus, infantile rhinallergosis, rheumatism, rheumatoism, scapulohumeral periarthritis, asthma, temporomandibular joint disturbance, ulcer, eczema ani, postoperative crissal edema, and so on. The apparatus has also well performed in the application of haematococcus pluvialis's laser mutagenesis breeding.
The optical parameters for the treatment of thromboangitis obliterans were presented. The penetration characteristics of 650nm laser diode interaction with human vessel and blood were also studied respectively. The extra-vascular irradiation instrumentation using 650nm diode laser was developed based on the above investigation, and it can be applied for the treatment of thromboangitis obliterans and other diseases. In clinical application, out of the 10 patients, including 7 males and 3 females that suffered from thromboangitis obliterans were treated with the extra-vascular irradiation instrumentation. 2 patients were suffered from upper limb, while the others were suffered from lower limb. Patient received 10 times treatment as a course, and the laser power for the first half-course was 20mW and ranged from 40mW to 80mW for the successively half-course. The total effective rate was 70 percent. A male patient in the third stage vasculitis of right foot without any improvement after treatment with traditional therapy but cured with diode laser irradiation after a course of treatment. The treatment mechanism of thromboangitis obliterans with diode laser was also briefly discussed.