• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.1
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• pp.90-95
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• 2014

The system design and the system performance analysis of 3D imaging laser radar system for the mapping purpose is addressed in this article. For the mapping, a push-bloom scanning method is utilized. The pulsed fiber laser with high pulse energy and high pulse repetition rate is used for the light source of laser radar system. The high sensitive linear mode InGaAs avalanche photo-diode is used for the laser receiver module. The time-of-flight of laser pulse from the laser to the receiver is calculated by using high speed FPGA based signal processing board. To reduce the walk error of laser pulse regardless of the intensity differences between pulses, the time of flight is measured from peak to peak of laser pulses. To get 3D image with a single pixel detector, Risley scanner which stirs the laser beam in an ellipsoidal pattern is used. The system laser energy budget characteristics is modeled using LADAR equation, from which the system performances such as the pulse detection probability, false alarm and etc. are analyzed and predicted. The test results of the system performances are acquired and compared with the predicted system performance. According to test results, all the system requirements are satisfied. The 3D image which was acquired by using the laser radar system is also presented in this article.

• Journal of Periodontal and Implant Science
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• v.26 no.4
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• pp.989-1002
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• 1996

The purpose of this study was to determine the effect of a pulsed Nd:YAG laser irradiation on human gingival tissues. The patients, who were planned to be treated by clinical crown lengthening procedure and gingivectomy, were selected. All the patients received oral hygiene instruction, scaling and root planing at preoperation. The crest of gingival tissue on upper and lower anterior teeth was irradiated by a pulsed Nd:YAG laser(El. EN. EN060, Italy) with a fiber optic of 300 m in contact mode for 20 seconds. Gingival tissues were divided into 4 groups according to the laser power of 1.0W(10Hz, 100mJ), 2.0W(20Hz, 100mJ), 3.0W(30Hz, 100mJ) and 4.0W(40Hz, 100mJ). Immediately after the laser irradiation, the specimens were excised, fixed 10% neutral formalin, sectioned $4-6{\mu}m$ thick, stained by Hematoxylin-Eosin and Periodic Acid Schiff stain and observed under light microscope. The removed tissue depth and the coagulated layer depth due to a laser irradiation by a laser irradiation were measured on the microphotographs. The difference of measurements according to the different laser power was statistical1y analyzed by Kruskal Wallis Test with SAS program. The results were as follows : 1. In histologic findings of irradiated gingival tissues; a. In the irradiated gingival specimen with 1.0W laser power, some vesicles were observed in limited superficial layer of gingival epithelium. b. In the irradiated gingival specimen with 2.0W and 3.0W laser power, the epithelium was almost removed except for the traces of viable basal cell remnants at ret peg, and coagulation necrosis related with the thermal effect of laser was noted. c. In the irradiated gingival specimen with 4.0W laser power, complete removal of epithelium, partial removal of underlying connective tissue, and the coagulation necrosis of subjacent gingival tissue were shown. 2. The removed tissue depth was deeper in the irradiated specimens with higher power. There was a statistical significance in the difference of removed tissue depth between 1.0W group ($44.54{\pm}6.99um$) and 3.0W group ($99.75{\pm}6.64{\mu}m$), and between 1.0W group($44.54{\pm}6.99{\mu}m$) and 4.0W group($111.36{\pm}4.50{\mu}m$), and between 2.0W group($98.01{\pm}4.53{\mu}m$) and 4.0W group($111.36{\pm}4.50{\mu}m$)(P<0.05). 3. The coagulated layer depth was deeper in the irradiated specimens with higher power. There was a statistical significance in the difference of coagulated layer depth between 1.0W group($31.82{\pm}8.99{\mu}m$) and 3.0W group($55.99{\pm}20.94{\mu}m$), and between 1.0W group($31.82{\pm}8.99{\mu}m$) and 4.0W group($83.68{\pm}10.34{\mu}m$)(P<0.05). From this study, the results demonstrated that the effects of a pulsed Nd:YAG laser irradiation on gingival tissues seemed to depend on the laser power and that the irradiation with high power could be harmful to adjacent healthy tissue.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.7-13
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• 2010

We report a hybrid DPSSL with a pulse parameter variable LD seed, all-fiberized polarization-maintained pulsed Yb-doped fiber preamplifier chains, and a bulk Nd:$YVO_4$ power amplifier. Pulse parameter of LD seed was controlled by direct current modulation. The hybrid DPSSL generates 1064 nm laser pulses with an average power of 40W, a pulse duration of 20-40ns, and a repetition rate of 100-500kHz.

• Journal of Periodontal and Implant Science
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• v.26 no.2
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• pp.511-521
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• 1996

Periodontal pocket is one of the most frequently developed clinical feature on the teeth with periodontal disease. In order to determine the gingival curettage effect of intrapocket irradiation of a pulsed Nd : YAG laser on periodontally involved teeth, bilateral 60 teeth with $4{\sim}6mm$ in probing pocket depth 1 week after supragingival scaling were selected. On half of them the intrapocket irradiation($300{\mu}m$ fiber optic, 1.5W power, for 2min.) of a pulsed-Nd : YAG laser(EL.EN.EN06O, Italy) was applied as the lased group. On the contralateral 30 teeth the subgingival curettage was accomplished by Gracey curettes as the curattage group. The periodontal pocket tissues were surgically excised by the modified Widman flap technique immediately after the intrapocket irradiation or subgingival curettage, subsequently fixed with 10% neutral formalin, sectioned in $4{\sim}6{\mu}m$ thickness, and stained with hematoxylin-eosin. Surface characteristics and incomplete removal of the pocket epithelium were evaluated under light microscope. And the difference between the lased group and the curettage group was statistically analyzed by Chi-square test in Microstat program. The results were as follows ; 1. The plane surface was observed more frequently in the curettage group(73.3%) than in the lased group(23.3%), and the rough surface was observed more frequently in the lased grOoup(63.3%) than in the curettage group(6.7%)(p<0.05). 2. The rate of incomplete removal of the pocket epithelium was relatively high in both the lased group(76.6%) and the curettage group(86.6%), and there was no significant difference between the lased group and the curettage group(p>0.l). The results suggest that the further studies including various power control of laser should be succeeded in order to obtain more favorable results by the intrapocket irradiation of a pulsed Nd:YAG laser than the subgingival curettage with Gracey curettes.

• Journal of Periodontal and Implant Science
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• v.52 no.1
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• pp.77-87
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• 2022

Purpose: This pilot study assessed the immediate in vivo effect of high peak pulse power neodymium-doped yttrium aluminum garnet (Nd:YAG) laser monotherapy on selected red/orange complex periodontal pathogens in deep human periodontal pockets. Methods: Twelve adults with severe periodontitis were treated with the Laser-Assisted New Attachment Procedure (LANAP®) surgical protocol, wherein a free-running, digitally pulsed, Nd:YAG dental laser was used as the initial therapeutic step before mechanical root debridement. Using a flexible optical fiber in a handpiece, Nd:YAG laser energy, at a density of 196 J/cm² and a high peak pulse power of 1,333 W/pulse, was directed parallel to untreated tooth root surfaces in sequential coronal-apical passes to clinical periodontal probing depths, for a total applied energy dose of approximately 8-12 joules per millimeter of periodontal probing depth at each periodontal site. Subgingival biofilm specimens were collected from each patient before and immediately after Nd:YAG laser monotherapy from periodontal pockets exhibiting ≥6 mm probing depths and bleeding on probing. Selected red/orange complex periodontal pathogens (Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia/nigrescens, Fusobacterium nucleatum, Parvimonas micra, and Campylobacter species) were quantified in the subgingival samples using established anaerobic culture techniques. Results: All immediate post-treatment subgingival biofilm specimens continued to yield microbial growth after Nd:YAG laser monotherapy. The mean levels of total cultivable red/orange complex periodontal pathogens per patient significantly decreased from 12.0% pretreatment to 4.9% (a 59.2% decrease) immediately after Nd:YAG laser monotherapy, with 3 (25%) patients rendered culture-negative for all evaluated red/orange complex periodontal pathogens. Conclusions: High peak pulse power Nd:YAG laser monotherapy, used as the initial step in the LANAP® surgical protocol on mature subgingival biofilms, immediately induced significant reductions of nearly 60% in the mean total cultivable red/orange complex periodontal pathogen proportions per patient prior to mechanical root instrumentation and the rest of the LANAP® surgical protocol.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.274-281
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• 1995

The new method of recording and reconstructing a synthetic object, which was called as scannedobject holography (SOH), was proposed and its feasibility was demonstrated theoretically and experimentally. The hologram was recorded by interfering the fixed reference beam with spherical waves emitting from a moving point source, whose trajectory determined the shape of the synthetic object to be recorded. The end face of an optical fiber and the output from a pulsed laser were utilized in order to implement a moving point source experimentally. tally.

• Journal of the Korean Vacuum Society
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• v.16 no.5
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• pp.371-376
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• 2007

We have investigated the lasing characteristics of the InGaAs quantum dot laser diode (QD-LD) and InGaAs quantum well laser diode (QW-LD) operated at the 980 nm wavelength range. The 980-nm lasers are used as a pumping source for a erbium-doped fiber amplifier (EDFA) and it shows high efficiency in long-haul optical fiber network. We have compared the threshold current density, the characteristic temperature, the optical power and the internal efficiency of QD-LD and QW-LD under a pulsed current condition. The QD-LD shows superior performances to the QW-LD. Further optimization of a LD structure is expected to the superior performances of a QD-LD.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1627-1627
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• 2001

In this study, a newly constructed optical measurement system, whose main components were a parametric tunable laser and a near infrared photoelectric multiplier, was applied to detection of the information for the inside of Satsuma mandarin using time-of-flight near infrared spectroscopy (TOF-NIRS). The combined effects on the time resolved profile of sample diameter, sugar content, the wavelength of the laser beam, and the detection position of transmitted light were investigated in detail. The samples used were Satsuma mandarin (Citrus unshu $M^{ARC}$.) (location: Wakayama, Japan) having the diameters of 50-84 mm. The sugar content measured by a refractometer varied from 9.9 to 16.3 Brix%. Equator of sample was irradiated vertically with the pulsed laser, and transmitted output power was measured on the restricted position of the equator using the optical fiber cable. The sampling time and the number of averaging the output power were 100 ns and 100 times, respectively. The variation of the attenuance of peak maxima At, the time delay of peak maxima t and the variation of full width at half maximum w were strongly dependent on the detection position and the wavelength of the laser beam. At, t and w increased gradually as the sample diameter increased to be much absorbed and vigorously scattered. On the other hand, each optical parameter had a tendency to increase as the sugar content increased. Such behavior was remarkable when the transmitted light was detected at the side face of a sample. When we apply TOF-NIRS to detection of the information for the inside of fruit with high moisture content like Satsuma mandarin, it is very important to give attention to the difference in the scattered light within tissues and the semi-straightly propagated light. Furthermore, we tried to express the resulting phenomena by using a model samples composed of water, sucrose, and milk. The variation of the time resolved profile is strongly governed by the combination of the light absorption component, scattering medium, and refractive index.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1626-1626
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• 2001

In this study, a newly constructed optical measurement system, whose main components were a parametric tunable laser and a near infrared photoelectric multiplier, was applied to detection of the information for the inside of Satsuma mandarin using time-of-flight near infrared spectroscopy (TOF-NIRS). The combined effects on the time resolved profile of sample diameter, sugar content, the wavelength of the laser beam, and the detection position of transmitted light were investigated in detail. The samples used were Satsuma mandarin (Citrus unshu $M_{ARC}$.) (location: Wakayama, Japan) having the diameters of 50-84 mm. The sugar content measured by a refractometer varied from 9.9 to 16.3 Brix%. Equator of sample was irradiated vertically with the pulsed laser, and transmitted output power was measured on the restricted position of the equator using the optical fiber cable. The sampling time and the number of averaging the output power were 100 ns and 100 times, respectively. The variation of the attenuance of peak maxima At, the time delay of peak maxima $\Delta$t and the variation of full width at half maximum Δw were strongly dependent on the detection position and the wavelength of the laser beam. At, $\Delta$t and $\Delta$w increased gradually as the sample diameter increased to be much absorbed and vigorously scattered. On the other hand, each optical parameter had a tendency to increase as the sugar content increased. Such behavior was remarkable when the transmitted light was detected at the side face of a sample. When we apply TOF-NIRS to detection of the information for the inside of fruit with high moisture content like Satsuma mandarin, it is very important to give attention to the difference in the scattered light within tissues and the semi-straightly propagated light. Furthermore, we tried to express the resulting phenomena by using a model samples composed of water, sucrose, and milk. The variation of the time resolved profile is strongly governed by the combination of the light absorption component, scattering medium, and refractive index.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.706-715
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• 2012

Electro-optical sigma-delta modulators are the core module of digital receiver to digitize wideband radio-frequency signals directly at an antenna. Electro-optical sigma-delta modulators use a pulsed laser to oversample an input radio-frequency signals at two Mach-Zehnder Interferometer(MZI) and shape the quantization noise using a fiber-lattice accumulator. Decimation filtering is applied to the quantizer output to construct the input signal with high resolution. The jitter affects greatly on reconstructing the original input signal of modulator. This paper analyzes the performance of first order single bit electro-optical sigma-delta modulator in the time domain and the frequency domain. The performance of modulator is analyzed by using asynchronous spectral averaging of the reconstructed signal's spectrum in the frequency domain. The reference value of time jitter is presented by analyzing the performance of jitter effects. This kind of jitter value can be used as a reference value on the design of modulators.