Single Optical Port Research Articles

Хірургічна корекція пахвинних гриж в дітей із застосуванням міні-інвазивного методу PIRS

Вступ. Пахвинна грижа (ПГ) — одне із найбільш поширених захворювань дитячого віку, що вимагають хірургічного лікування. Основним показанням до оперативного лікування ПГ є ризик її защемлення. Серед способів лапароскопічної герніорафії особливо перспективним є метод PIRS (percutaneous internal ring suturing). Мета роботи — провести аналіз власного клінічного матеріалу хірургічного лікування ПГ у дітей із використанням методу PIRS. Матеріали та методи. У дослідження включено 62 дитини з ПГ віком від 2 місяців до 7 років, яких прооперували впродовж 2012–2015 років методом PIRS з ушиванням внутрішнього кільця пахвинного каналу. Серед пацієнтів було 48 (77,4 %) хлопчиків і 14 (22,6 %) дівчат. Правобічну грижу діагностовано в 45 (72,6 %) хворих, а лівобічну — у 10 (16,1 %). Двобічну ПГ перед операцією діагностовано в 7 (11,3 %) дітей. Для оперативних втручань використовували прямий або 30° лапароскоп 5 мм.Результати та обговорення. Серед переваг лапароскопічних методів, і зокрема способу PIRS, виділяють можливість виявлення незарощення вагінального паростка очеревини з контралатерального боку. Так, у 6 (9,7 %) хворих розширення внутрішнього кільця пахвинного каналу з протилежного боку візуалізовано інтраопераційно. Також перевагами цього методу є використання лише одного оптичного порту діаметром 3–5 мм та відсутність потреби в накладанні інтракорпоральних швів. Жоден оперований пацієнт при застосуванні нитки Ethibond* Excel 2–0 не скаржився в післяопераційному періоді на неприємні відчуття в ділянці післяопераційного вузла, що розміщували підшкірно в пахвинній ділянці. У дослідженні рецидив ПГ виявлено в 2 (3,2 %) хлопчиків. Цих пацієнтів повторно також прооперовано з використанням методики PIRS. Висновки. PIRS — простий та ефективний міні-інвазивний метод хірургічної корекції ПГ, що дає добрий косметичний результат. Застосування лапароскопічного методу в лікуванні ПГ у дітей дозволяє ретельно оглянути внутрішні кільця пахвинних каналів і, за потреби, виконати корекцію вади з обох боків. Використання нитки Ethibond* Excel 2–0 для ушивання внутрішнього кільця пахвинного каналу є ефективним та дає оптимальні функціональні результати. Ризик рецидиву ПГ після операції методом PIRS є порівнянним з ризиком рецидиву після операції класичним методом.

Time-resolved, single-ended laser absorption thermometry and H2O, CO2, and CO speciation in a H2/C2H4-fueled rotating detonation engine

Rotating detonation engines (RDEs) require novel diagnostic tools to better understand complex detonation behavior and improve performance. To this end, a single-ended laser absorption sensor for in situ, time-resolved measurements of temperature, H2O, CO2, and CO concentrations has been developed and deployed within the annulus of a hydrogen/ethylene/air-fed RDE. With a measurement rate of 44 kS/s, the sensor delivers four co-aligned, mid-infrared laser beams into the annular detonation chamber and captures the back-reflected radiation through a single optical port. A ray-tracing optimization algorithm, designed to maximize signal-to-noise ratio and beam-perturbation tolerance, was used to determine the optimal sensor optical configuration. Wavelength-modulation spectroscopy (WMS) further compensated for interference sources in the harsh detonation environment. Time-resolved and time-averaged sensor measurements of gas temperature and species at equivalence ratios of 0.74, 0.87, and 1.03 are presented.

Method and apparatus for measuring the stability of large lateral transfer retroreflectors through a single optical port.

Achieving precise alignment between spatially separated optical axes is a challenging problem in optical applications such as boresighting, rangefinding, laser tracking, and optical beam delivery. The Advanced Topographic Laser Altimeter System (ATLAS) developed for NASA's Ice, Cloud and Land Elevation Satellite-II (ICESat-2) mission launched in 2018 was one such application where the alignment of the transmitter laser beam to the receiver telescope is critical for the operation of the instrument. This paper discusses a novel approach for verifying the stability of high-precision beam pointing in the conditions of the Thermal Vacuum (TVAC) test, developed for ATLAS testing at NASA Goddard Space Flight Center. It includes a method and an optical assembly that enables measuring tiny variations in the pointing of the beams of a large lateral transfer retroreflector through a single optical access port such as a TVAC chamber window. The method can be applied for verifying the alignment of optical beams separated by extended distances of tens of meters in vacuum.

Single-Ended Sensor for Thermometry and Speciation in Shock Tubes Using Native Surfaces

A single-ended laser absorption sensor for time-resolved measurements of temperature and H2O, CO2, and CO concentrations was designed and deployed on a cylindrical shock tube operating at combustion-relevant conditions. The sensor transmitted four monochromatic laser beams probing strong species-specific mid-infrared absorption transitions through a single optical port and measured the backscattered laser radiation from the native surface across the 13.97-cm-diameter shock tube. Despite the non-ideal concave reflective surface and the long optical path relative to the port diameter (1.37 cm), an optimal optical configuration that maximized signal-to-noise ratio and was free of physical blockage was found and implemented using a numerical ray-tracing optimization algorithm. Wavelength-modulation spectroscopy was employed to further compensate for interference sources in the shock tube environment. The four lasers were sinusoidally injection-current modulated at various frequencies near 100 kHz to yield a measurement rate of 44 kS/s. Demonstration measurements involving non-reacting mixtures of the target species and reacting mixtures of ethane and oxygen in a N2 bath were performed in a shock tube facility at temperatures between 1100 and 1800 K and pressures between 2 and 9 atm, with measured quantities demonstrating excellent agreement with the expected values. Despite experiencing strong vibrations induced by the dynamic shock tube environment, the sensor resolved sub-millisecond transients during ethane oxidation and detected H2O, CO2, and CO mole fractions as low as 0.025%, 0.012%, and 0.005%, respectively, representing highly sensitive detection limits suitable for single-port low-concentration multi-species sensing in shock tubes and other flow channels of comparable dimensions.

Single-ended mid-infrared laser-absorption sensor for time-resolved measurements of water concentration and temperature within the annulus of a rotating detonation engine

Abstract A novel single-ended mid-infrared laser-absorption sensor for time-resolved measurements of water mole fraction and temperature was developed and deployed within the annulus of a hydrogen/air-fed rotating detonation engine (RDE). The sensor transmitted two laser beams targeting mid-infrared water transitions through a single optical port on the outer wall of the cylindrical RDE annulus and measured the backscattered radiation from the RDE inner surface using a photodetector for a round-trip path of 1.52 cm. Optimizing the sensor's optical arrangement using numerical ray tracing to minimize interference from optical emission, beam steering, and scattered laser light from window surfaces was essential to sensor performance. Scanned-wavelength-modulation spectroscopy with second-harmonic detection and first-harmonic normalization was implemented to allow for frequency-domain multiplexing of the two lasers and to suppress non-absorbing interference sources such as beam-steering and emission. Tunable diode lasers near 2551 and 2482 nm were modulated at 100 and 122 kHz, respectively, and sinusoidally scanned across the peaks of their respective water transitions at 10 kHz to provide a measurement rate of 20 kHz and detection limit of 0.5% water by mole. Experimentally derived spectroscopic parameters enabled water and temperature sensing with respective uncertainties of 7.3% and 5.3% relative to the measured values. Time-resolved and time-averaged sensor measurements of gas temperature and water vapor mole fraction allow quantitative evaluation of the combustion progress at the measurement location and thus provide a design tool for RDE optimization. Broadly, this single-ended laser sensor should find applications in other combustion systems where optical access is limited.

Single-ended mid-infrared laser-absorption sensor for simultaneous in situ measurements of H2O, CO2, CO, and temperature in combustion flows.

The development and demonstration of a four-color single-ended mid-infrared tunable laser-absorption sensor for simultaneous measurements of H2O, CO2, CO, and temperature in combustion flows is described. This sensor operates by transmitting laser light through a single optical port and measuring the backscattered radiation from within the combustion device. Scanned-wavelength-modulation spectroscopy with second-harmonic detection and first-harmonic normalization (scanned-WMS-2f/1f) was used to account for variable signal collection and nonabsorption losses in the harsh environment. Two tunable diode lasers operating near 2551 and 2482 nm were utilized to measure H2O concentration and temperature, while an interband cascade laser near 4176 nm and a quantum cascade laser near 4865 nm were used for measuring CO2 and CO, respectively. The lasers were modulated at either 90 or 112 kHz and scanned across the peaks of their respective absorption features at 1 kHz, leading to a measurement rate of 2 kHz. A hybrid demultiplexing strategy involving both spectral filtering and frequency-domain demodulation was used to decouple the backscattered radiation into its constituent signals. Demonstration measurements were made in the exhaust of a laboratory-scale laminar methane-air flat-flame burner at atmospheric pressure and equivalence ratios ranging from 0.7 to 1.2. A stainless steel reflective plate was placed 0.78 cm away from the sensor head within the combustion exhaust, leading to a total absorption path length of 1.56 cm. Detection limits of 1.4% H2O, 0.6% CO2, and 0.4% CO by mole were reported. To the best of the authors' knowledge, this work represents the first demonstration of a mid-infrared laser-absorption sensor using a single-ended architecture in combustion flows.

Two photon absorption laser induced fluorescence measurements of neutral density in a helicon plasma

We have developed a new diagnostic based on two-photon absorption laser induced fluorescence (TALIF). We use a high intensity (5 MW/cm2), narrow bandwidth (0.1 cm−1) laser to probe the ground state of neutral hydrogen, deuterium and krypton with spatial resolution better than 0.2 cm, a time resolution of 10 ns, and a measurement cadence of 20 Hz. Here, we describe proof-of-principle measurements in a helicon plasma source that demonstrate the TALIF diagnostic is capable of measuring neutral densities spanning four orders of magnitude; comparable to the edge neutral gradients predicted in the DIII-D tokamak pedestal. The measurements are performed in hydrogen and deuterium plasmas and absolute calibration is accomplished through TALIF measurements in neutral krypton. The optical configuration employed is confocal, i.e., both light injection and collection are accomplished with a single lens through a single optical port in the vacuum vessel. The wavelength resolution of the diagnostic is sufficient to separate hydrogen and deuterium spectra and we present measurements from mixed hydrogen and deuterium plasmas that demonstrate isotopic abundance measurements are feasible. Time resolved measurements also allow us to explore the evolution of the neutral hydrogen density and temperature and effects of wall recycling. We find that the atomic neutral density grows rapidly at the initiation of the discharge, reaching the steady-state value within 1 ms. Additionally, we find that neutral hydrogen atoms are born with 0.08 eV temperatures, not 2 eV as is typically assumed.

VID-09.01 Advantages of Single Optical Port in Laparoscopic Bilateral Adrenalectomy Cepeda

The removal of the adrenal gland under laparoscopy is the gold-standard treatment in benign tumor pathology, leaving the technical challenge in this regard limited to the size of the lesion, presence or absence of bilateral illness and skills of the surgeons. We show in this video a case of a obese female patient aged 46, with a clinical diagnosis of Cushing's Syndrome, CT images of bilateral adrenal gland volume increase, who is operated in a bilateral laparoscopic approach as an option therapy with a single optical port.

Pyrometric measurement of the temperature and size of individual combusting fuel particles

A two-color pyrometric technique was developed for the in situ simultaneous measurement of individual fuel-particle temperatures and sizes in a pressurized entrained flow reactor (PEFR). A method that requires only a single optical port was developed, and a specially designed optical probe was manufactured for the measurements at the PEFR. The fuel-particle temperature was obtained by applying two-color pyrometry. The particle size was determined from the same pyrometric signals. A discrimination method was developed to confirm that the detected particle was valid for particle sizing. Several series of measurements were made at a PEFR at different process conditions, and some typical results are shown.

Oblique laser-sheet visualization

A laser-sheet visualization technique is demonstrated in which the laser and camera systems are integrated into a single unit, reducing the need for optical access to a single optical port. The technique is based on the photographing of a plane oblique to the camera optical axis and has been successfully applied to the quarl region of a power-station pulverized coal burner. The geometry of oblique photographing is presented.