Rapid thermal annealing that utilizes broadband flash lamp sources requires optical diagnostics for instantaneous thermal mapping of silicon wafers and its in-situ monitoring during the process. A new split channel optical assembly offering simultaneous imaging via CMOS- and FPA-imager was designed. Reverse telephoto optical design allows
distortion of <2.5% in both imaging paths over the field of view of ±18° with deep field range and no instrument
protrusion into the semiconductor process chamber. Application of solarization resistant materials in a first negative
group as well as a rugged housing suits the design to optically harsh environments. Additional stray light measures were
taken to control heat dissipation inside the narrow lens barrel by the arrangement of refractive surfaces and absorptive
baffles. The beam splitter in front of a second positive group is made of silicon, which both provides preliminary
spectral filtering in the near infrared through-channel and further extends spectral capabilities of the visible (reflected)
channel into UV-B region. Detailed lens performance, manufacturing aspects and other use of the lens - for direct
discrimination of water-containing objects from the image pattern are reviewed.
A novel hypericin-based drug HyperflavTM has been evaluated for light-induced fluorescence detection of oral cancer. Squamous cell carcinoma was induced with carcinogenic agent in right pouches of forty hamsters (20/20 males/females). Solution of HyperflavTM was sprinkled into stomach with a single dose 0.2 - 4 mg of pure hypericin per kg b.w. and 4 - 8 hours before fluorescence analysis. In two animal groups with cancer symptoms the autofluorescence and hypericin-induced fluorescence were taken under 442 nm excitation. The buccal mucosa and adjacent areas were measured fiberoptically in-vivo and in-vitro using orange/green ratio (610/540). The in-vivo fluorescence imaging of malignant areas was conducted to assist the biopsy guidance and to compare with white-light images. Histological and morphological analyses were performed from biopsies. Oral squamous cell carcinoma in its early stage demonstrated specific higher 610/540 ratio for 37 tested hamsters. Advanced state involved another higher fluorescence maximum around 640 nm that in our opinion caused by strong porphyrin-induced native fluorescence. Such deformation of fluorescence spectra may lead to inadequate perception of diseased tissue area. To avoid this problem the autofluorescence spectra & images were added. HyperflavTM application is promising for demarcation of early oral cancer when combined with autofluorescence measurements.
We considered the limited number of light-induced fluorescence applications for marketed ultra-bright blue LEDs where they can compete with versatile laser sources. Satisfactory optical output and miniature size as well as low power consumption of blue LEDs emitting at 470 nm allow to consider them as a promising alternatives to metal vapor or gas lasers used in many expires LIF applications. Available to authors LEDs form Hewlett-Packard, Micro Electronics Corp., Nichia Chemical Industries Ltd. and Toyoda Gosei Co. were tested to comply with demands to a tissue excitation source for portable spectroscopes. The optical performance of LEDs has shown that selected group of InGaN LEDs could be successfully used for that. The miniature illuminator that includes LED, focusing condenser, filter set and distal fiberoptic light concentrator was designed and tested in conjunction with portable CCD- equipped spectroscope. Operating in dark condition the proposed LED illuminator provides the level of fluorescence signal sufficient to detect spectral abnormalities in human Caucasian skin and excised gastrointestinal samples. All tissue autofluorescence data taken under LED illumination were compared with readings under He-Cd laser excitation and showed a good match. A new diagnostic designs based on LEDs were considered for clinical use.
Optical biopsy of stomach mucosa was performed afterwards oral administration of encapsulated hyperflav (single dose was chosen to provide 0.1 - 0.15 mg/kg b.w.) A sufficient fluorescence contrast of suspicions versus normal tissue was obtained after incubation time from 4 to 10 hours. Fluorescence was induced by He - Cd laser coupled to fiber optic probe inserted into a biopsy channel of the endoscope. Fluorescent spectra were recorded in the range from 500 nm up to 700 nm with 2 nm resolution. We took two groups of patients with benign and malignant ulcer of the stomach and erosive gastritis. The first group consisted of 59 patients (male/female 36/23) was carried out with optical biopsy of stomach mucosa. The second group consisted of 60 patients (male/female 39/21) was carried out by routine method: gastroscopy and biopsy from 5 - 7 places of macroscopically changed mucosa.
Assessment of tooth color by visual evaluation is a complex task. A number of attempts to build a reliable instrument that can measure the color of teeth have been undertaken in the last 15 years. These attempts were aimed at using conventional colorimeters designed for color measurement of oblique objects. However, the translucency of teeth strongly affected the colorimeters' readout because of the size of the measuring aperture and the geometry of the spectroscope. Here we present the results of our spectroscopic study of dental materials and human teeth that show a characteristic behavior of optical spectra collected with a fiberoptic probe. The probe consisted of 300 micrometer irradiating and 1 mm detecting fibers that were coupled to a white light source (color temperature 6500 K) and to a spectroscope. The conventional shades from Vita and Chromascop shade guides were measured with different location of the fibers. The color of the dental shades was measured by a standard spectrophotometer with two different apertures. We found that registered spectra depended on fiber position and color coordinates changed with aperture size. The influence of the fiber positioning was approved with color measurement of vital teeth. A simplified colorimetric system based on two color coordinates, lightness L*, and the difference, (a* - b*), has been proposed. Finally, we describe a novel dental color matching device based on a fiberoptic probe. The device is able to classify all dental shades from Vita, Chromascop, and Bioform shade guides and is aimed at better color matching of restorative materials to native teeth.
The fluorescence spectra from stomach mucosa have been measured for cancer diagnostics using hypericin as a photosensitizer. Hypericin was administered orally in amount of 0.1 mg/kg b.w. four hours before conventional endoscopic procedure. Fluorescence was induced by He-Cd laser coupled to optical fiber probe which was inserted into a biopsy channel of the endoscope; the output power at the distal fiber end was 6 mW. Fluorescent light was collected fiber optically and registered by a spectroanalyzer in the range up to 700 nm. Detection algorithm included a comparison of characteristic orange fluorescence of hypericin at 600 nm with fluorescence at 530 nm in conjunction with results of white-light endoscopy. Fluorescence procedure was performed in thirty-seven patients with various oncological and other stomach disorders. It has shown an average 90 percent specificity in detection of small size lesions. Developed technique is promising to detect early stomach cancers and indicate an advantage of laser induced fluorescence with photosensitizer hypericin in differential cancer diagnostics.
During the clinical endoscopic LIF-diagnostics of human digestion organs is needed to register fluorescence spectra in situ. Taking into account intensive bloodstream and therefore strong hemoglobin absorption of laser light the registered fluorescence signal is strongly dependent on distal probe geometry. The contact optics sensor is specially designed to enhance acquisition of auto- and exogenous fluorescence spectra from tissues. The fiber optics sensor consists of cylindrical sapphire or silica body with flat proximal and spherical distal end and tapered tip. The latter one has been made of optical material. This tip has been arranged abutting against the proximal end of the cylindrical body. Such sensor design offers to collect autofluorescent light in wide angle region effectively. Moreover that offers to use sensor simultaneously as an efficient both laser radiation collector and fiber coupler to transport exciting light at the testing site and backward. The produced distal probe has been used through the biopsy channel to endoscope. Original beam splitter throws 80% of fluorescent signal toward detector and simultaneously transmits up to 85% of He-Cd laser radiation to the tissue.
One of the most important problems in modern laser medicine is the determination of system response on laser treatment. Reaction of living system is significant during many kinds of laser procedures like surgery, therapy and biostimulation. Our study was aimed to optimize laser exposure using feed-back fiber system for intravenous laser irradiation of blood (ILIB). This system consisted of helium-neon laser (633 nm, 5 mW) with coupled fiber unit, photodetector and PC interface. Photodetector signals produced due to light backscattering were storaged and processed during all blood irradiation procedure. Significant time-dependent variations were observed within 9-15 min after beginning of treatment procedure and were correlated with number of trials, stage and character of disease. The designed feed-back system allows us to register a human blood response on laser irradiation to achieve better cure effect.
Natural photodynamic pigment hypericin having intrinsic antitumor properties was applied for fluorescence detection of cancer. Clinical investigation of hypericin was performed to ensure high tumor/normal fluorescence contrast in digestion organs. Laser-induced autofluorescence and exogenous fluorescence analysis of normal tissue and stomach adenocarcinoma was performed using helium-cadmium laser (8 mW, 442 nm). Twenty-one patients have undergone procedure of fluorescence detection of tumors before and after photosensitization. For sensitization of patients we used five or seven capsules containing hypericin in amount of 1 mg which have been administered orally. Strong yellow-red fluorescence of hypericin in tissue with maximum at 603 nm and autofluorescence peak at 535 nm gives an intensity ratio I(603 nm)/I(535 nm) of 2 - 2.5 from cancerous tissue and provides 85% specificity. Preliminary in vivo results of auto- and fluorescence analysis using hypericin photosensitization from one patient with esophageal cancer and eleven patients with stomach cancer proven histologically are encouraging and indicate the high reliability of laser-induced fluorescence technique with hypericin in detection of early stage malignant lesions.
Biomedical science and practical medicine need special techniques for reliable real-time remote detection and determination information from human tissue. Most applications of these techniques in interior organs are based on optical fibers which should not only be able to deliver excitation light with minimal loss but provide effective light gathering from tissue being under the test. As emitted from tissue optical signal is often weak especially if autofluorescence spectroscopy is chosen for diagnostics, an efficient collection by fiber optics probe became essential. The main part of the proposed fiber optics probes is a specially designed tapered tip with one flat surface and another spherical one. This tip operates as a collector, transmitter and coupler to deliver light to the tissue and backward to the detector simultaneously. To find geometrical dimensions of tips optimized for these purposes calculating formulas have been adduced. These optimized tips could collect fluorescence signal from biological sites in wide angular aperture region and could transport light without leakage on tapered surface. When delivery fibers are placed at the focal plane of tip spherical surface an efficient optical coupling with them is achieved. Ray tracing of the tapered tips has been performed on sapphire and quartz tip materials in air and in saline to determine the best sensor design.
Intravenous laser blood irradiation as an effective method of biostimulation and physiotherapy becomes a more popular procedure. Optimal irradiation conditions for each patient are needed to be established individually. A fiber optics feedback system combined with conventional intravenous laser irradiation system was developed to control of irradiation process. The system consists of He-Ne laser, fiber optics probe and signal analyzer. Intravenous blood irradiation was performed in 7 healthy volunteers and 19 patients with different diseases. Measurements in vivo were related to in vitro blood irradiation which was performed in the same conditions with force-circulated venous blood. Comparison of temporal variations of backscattered light during all irradiation procedures has shown a strong discrepancy on optical properties of blood in patients with various health disorders since second procedure. The best cure effect was achieved when intensity of backscattered light was constant during at least five minutes. As a result, the optical irradiation does was considered to be equal 20 minutes' exposure of 3 mW He-Ne laser light at the end of fourth procedure.
Fluorescence signal during tissue LIF-analysis depends on both excitation conditions and tissue optics, registration optics and location of the probe relative to tissue sample as well. To develop reliable fiber optic probes and optimize their position the spatial distribution of tissue fluorescence should be studied. Fluorescence indicatrices of skin of rat were measured in angular range of 80 degrees. Excited light from He-Cd (20 mW, 442 nm) laser was delivered on the cutaneous surface at the angular range from 0 to 60 degrees with the tissue surface. Fluorescence was registered in the spectrum between 530 nm and 700 nm with 1.5 nm resolution. Autofluorescence of the skin of 5 white rats was studied in-vivo. Local application of sensitizer hypericin was used for stimulated fluorescence studies. Fluorescence indicatrices were not corresponded to scattering ones under the same conditions and depended on incident angle of excitative laser beam. No influence of polarization of excitative beam on outside fluorescence distribution was observed. Maximum in-vivo fluorescence yield was registered at the normal incidence. There were observed marked differences between spatial distribution of normal and photosensitized rat skin tissues.
Hypericin has been studied as a novel natural photosensitizer for PDT. It has been extracted from plants (St.-John's-wort). Oral administration (10% alcohol solution in a dose 2 mg/kg b.w.) was applied for 15 patients with gastric cancers 18 - 48 h before surgery. Normal and cancerous tissue samples were resected and underwent fluorescence analysis 1 - 2 h after resection. Tissue fluorescence was excited by He-Cd (20 mW, 442 nm) and Ar laser beams (100 mW, 488 nm) and registered from 510 to 725 nm. In tissue hypericin has maximum fluorescence peak at 603 nm for both excitation wavelengths. Fluorescence intensity ratio I603/I503 chosen as a criterion for tissue classification was varied from 1.6 to 3.2 (mean 2.5) for adenocarcinoma under He-Cd excitation whereas Ar laser excitation gave from 2.5 up to 4.2 (mean 3.5). Normal tissue had this ratio from 0.48 to 0.65 (mean 0.55) and from 0.53 to 0.75 (mean 3.5) for He-Cd and Ar laser excitation, respectively. No side effects were observed in patients during 6 month follow-up.
Fluence rate was measured in normal and cancerous (glioma) human brain samples using a multichannel detector. Detector consisted of 8 isotrope fiber probes positioned around the central irradiating probe. Detecting probes were displaced one from other at a step 0.5 mm along the central irradiating fiber. Bare ends of detecting fibers were coupled with photodiode array. He-Ne (633 nm) or Nd:YAG (1064 nm) lasers were coupled with irradiating probe. Fluence rate was measured in each of 8 points in the depth range 5 mm. Measured mean penetration depths of 633 nm light were 0.70 mm, 0.50 mm and 0.40 mm for white matter, grey matter and glioma, respectively. For Nd:YAG laser, penetration depth was about 2.3 mm for normal tissue and glioma. Multichannel computerized detector allows to provide a small invasive real-time measurements of fluence rate in different tissues.
Laser beam propagation inside tissues with different lateral dimensions has been considered. Scattering and anisotropic properties of tissue critically determine spatial fluence distribution and predict sizes of tissue specimens when deviations of this distribution can be neglected. Along the axis of incident beam the fluence rate weakly depends on sample size whereas its relative increase (more than 20%) towards the lateral boundaries. The finite sizes were considered to be substantial only for samples with sizes comparable with the diameter of the laser beam. Interstitial irradiance patterns simulated by Monte Carlo method were compared with direct measurements in human brain specimens.
Bent multimode optical fibers were studied using a 3D ray tracing program. Effect of fiber bending increased with smaller input aperture beams. Transmission of fibers decreased for the longer proximal straight part of the fiber. Significant focusing effect and output light redistribution were detected if a proximal straight part of the fiber was less than 1 fiber diameter. Transmission of hollow waveguides considerably depended on the inner surface quality. Calculated data were in accordance with experimental measurements of fiber transmission and output light distribution. Ray tracing is a useful approach to simulate different delivery systems using optical fibers and hollow waveguides.
The paper is devoted to the investigation of full losses into the waveguide cavities that are platelet single crystals of semiconductors A2B6. Description of character of additional lines appearance in laser generation spectra is presented. It is shown that the section of symmetric waveguide which is the microlaser cavity creates such conditions of propagation and reflection from the facets for some transverse high-order modes that full losses coefficient of these modes at wavelength (lambda) becomes considerably less than the Urbach absorption coefficient at the same wavelength. The experimental researches of CdS single crystal generation spectra have been conducted and the interconnection between full losses and geometrical parameters of cavity have been established.
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