Coaxial Telescope Research Articles

Lumboscopic-Assisted Pyeloplasty: A Single-Port, Retroperitoneoscopic Approach for Children with Pelvi-Ureteric Junction Obstruction.

Introduction:Pelvi-ureteric junction obstruction (PUJO) is one of the most common conditions presenting to a pediatric urologist. As laparoscopic or robotic-assisted pyeloplasty, either transperitoneal or retroperitoneal, involves intracorporeal suturing skills and has a long learning curve, they have not gained popularity among beginners in laparoscopy.Objective:We conducted a study to assess the results of a single-port, retroperitoneoscopic approach to renal access, i.e. lumboscopic-assisted pyeloplasty (LAP), by single surgeon at our institute.Materials and Methods:A retrospective review of all children who underwent LAP from July 2013 to March 2018 was conducted. Patients who presented with PUJO and required surgical treatment were included. A single-port lumboscopy using coaxial telescope was performed in prone position in all patients. The renal pelvis was dissected and retrieved through the port site followed by extracorporeal hand-sewn pyeloplasty over a double–J stent or a nephrostent. The operative time, postoperative pain, surgical complications, duration of hospital stay, follow-up, and cosmesis at 6 months postsurgery were evaluated.Results:A total of 96 children were included (72 males and 24 females), with the age at operation ranging from 3 months to 10 years (mean = 4.9 years). All patients had an uneventful postoperative recovery. Two patients had a superficial wound infection, and one patient was converted to open approach due to excessive bleeding. The average operating time was 80 ± 22.5 min, the median duration of hospital stay was 3 days, and the average scar length at 3 months was 15.6 ± 0.4 mm. Follow-up renogram (diethylenetriamine pentaacetic acid) showed satisfactory postpyeloplasty drainage pattern in 93 children while three showed obstructive drainage curves.Conclusion:LAP can be performed safely with minimal retroperitoneal dissection, excellent cosmetic results, and minimal postoperative pain in children with PUJO. It has a shorter learning curve as compared to laparoscopic pyeloplasty as it involves time tested extracorporeal hand-sewn anastomosis.

Detection of concentration small gas components of atmosphere by DOAS method

A differential optical absorption spectroscopy (DOAS) gas-analyzer was successfully tested. A high pressure 150-W Xe arc lamp was employed as a light source. This system consisted of a coaxial telescope, a spectrometer, an analyzer and retroreflector. In order to record the spectra, a monochrometer with a grating and photodiode array was adopted. Gas analyzer spectral data bank includes more than 30 moleculas absorbed in UV spectral region. The measured absorption spectra were evaluated by using a least-squares to determine the average mixing ratio of each species in the atmosphere. A number of air pollutants concentrations: SO2, NO2, O3, etc were trace measured. Minimally detected concentration on pathlength 400 m is the unit of ppb at the time of accumulation of 2 min. The results of the field test measurements of pollutants in Tomsk are presented.

Tandem gratings spectrometer for spectroscopy broadband anastigmatic imaging

A tandem gratings spectrometer with high imaging quality is designed. By applying the geometric analysis, the spectral broadband anastigmatic imaging conditions have been obtained. It offers an advanced design with low aberrations for the whole spectral range of the small-scale spectrometer both in the off-axis and coaxial telescope applications. A UV design exhibiting excellent optical performance is presented. The specifications of design have also been investigated.

Advanced astigmatism-corrected tandem Wadsworth mounting for small-scale spectral broadband imaging spectrometer

Tandem gratings of double-dispersion mount make it possible to design an imaging spectrometer for the weak light observation with high spatial resolution, high spectral resolution, and high optical transmission efficiency. The traditional tandem Wadsworth mounting is originally designed to match the coaxial telescope and large-scale imaging spectrometer. When it is used to connect the off-axis telescope such as off-axis parabolic mirror, it presents lower imaging quality than to connect the coaxial telescope. It may also introduce interference among the detector and the optical elements as it is applied to the short focal length and small-scale spectrometer in a close volume by satellite. An advanced tandem Wadsworth mounting has been investigated to deal with the situation. The Wadsworth astigmatism-corrected mounting condition for which is expressed as the distance between the second concave grating and the imaging plane is calculated. Then the optimum arrangement for the first plane grating and the second concave grating, which make the anterior Wadsworth condition fulfilling each wavelength, is analyzed by the geometric and first order differential calculation. These two arrangements comprise the advanced Wadsworth mounting condition. The spectral resolution has also been calculated by these conditions. An example designed by the optimum theory proves that the advanced tandem Wadsworth mounting performs excellently in spectral broadband.