Interferometric measurement of distance using a femtosecond frequency comb is demonstrated and compared with a counting interferometer displacement measurement. A numerical model of pulse propagation in air is developed and the results are compared with experimental data for short distances. The relative agreement for distance measurement in known laboratory conditions is better than 10(-7). According to the model, similar precision seems feasible even for long-distance measurement in air if conditions are sufficiently known. It is demonstrated that the relative width of the interferogram envelope even decreases with the measured length, and a fringe contrast higher than 90% could be obtained for kilometer distances in air, if optimal spectral width for that length and wavelength is used. The possibility of comb radiation delivery to the interferometer by an optical fiber is shown by model and experiment, which is important from a practical point of view.

• MeSH
• algoritmy * MeSH
• analýza selhání vybavení MeSH
• atmosféra analýza   chemie   MeSH
• design s pomocí počítače MeSH
• design vybavení MeSH
• interferometrie přístrojové vybavení   MeSH
• lasery * MeSH
• radiační rozptyl MeSH
• reprodukovatelnost výsledků MeSH
• senzitivita a specificita MeSH
• světlo MeSH
• vzduch * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Chloride (Cl-) is an inorganic anion present in a broad range of samples (e.g. biological, environmental, food, water, etc.), the determination of which is of widespread significance. In this work, we translate the well-established traditional argentometric method (Mohr's precipitation titration) into a small, simple, portable, and low-cost paper-based microfluidic diagnostic device, which provides rapid and quantitative analysis. The developed device enables the determination of chloride sample volumes as small as 5 μL. A distance-based detection method is implemented providing fully instrument-free quantitation. The beneficial effects of channel geometry (variable widths with constant heights) on analytical parameters were investigated. Trapezoidal channels (channel width changes linearly with height) were used to create a gradient of paper surface (titrant) available for the reaction, compared to the typical uniform rectangular channels (constant channel width). The trapezoid with increasing width offered higher sensitivity and lower detection limits (i.e. 0.05 mM vs 0.1 mM from the rectangular channel) for chloride determination across the concentration range of 0.05-25 mM. In addition, the effect of concentration of the deposited reagent on the obtained distance signals was investigated using varying concentrations of titrant (AgNO3), which allowed determination of chloride across a wider dynamic range (up to 200 mM). The utility of the paper devices was demonstrated by determination of chloride in a variety of matrices including body fluids (sweat, serum, and urine) and water samples (drinking, mineral, river water).

• Klíčová slova
• Argentometric determination, Asymmetric trapezoidal microfluidic channels, Chloride determination, Distance-based measurement, Microfluidic paper-based analytical device,
• MeSH
• chloridy analýza   MeSH
• lidé MeSH
• mikrofluidní analytické techniky * MeSH
• papír * MeSH
• povrchové vlastnosti MeSH
• tělesné tekutiny chemie   MeSH
• voda chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chloridy MeSH
• voda MeSH

We propose a new commercial laser triangulation sensor modification to enable the measurement of slots or bores side distance. The study showed the possibility of extending the sensor depth range for a slot or bore side distance measurement using a bypass of the illumination laser beam compared to a simple single mirror attachment to the sensor probe. We derived relations allowing for evaluation of the modified sensor side measurement range in desired depth based on the sensor parameters and the reflective mirror size and position. We demonstrated the functionality of the proposed measurement arrangement with an attachment to the commercial laser triangulation sensor and assessed the side-wall distance measurement. The results show the correct measurement depth and range prediction and the ability to perform side surface distance measurements at depths of more than 3.5 times the slot size.

• Klíčová slova
• aspect ratio, bore, distance measurement, edge, laser triangulation, mirror, slot,
• Publikační typ
• časopisecké články MeSH

Among other things, passive methods based on the processing of images of feature points or beacons captured by an image sensor are used to measure the relative position of objects. At least two cameras usually have to be used to obtain the required information, or the cameras are combined with other sensors working on different physical principles. This paper describes the principle of passively measuring three position coordinates of an optical beacon using a simultaneous method and presents the results of corresponding experimental tests. The beacon is represented by an artificial geometric structure, consisting of several semiconductor light sources. The sources are suitably arranged to allow, all from one camera, passive measurement of the distance, two position angles, the azimuth, and the beacon elevation. The mathematical model of this method consists of working equations containing measured coordinates, geometric parameters of the beacon, and geometric parameters of the beacon image captured by the camera. All the results of these experimental tests are presented.

• Klíčová slova
• LED, camera, measurement errors, optical beacon, passive position measurement, simultaneous method,
• Publikační typ
• časopisecké články MeSH

The aim of the research is to analyze the possibility of the development and realization of a common laser triangulation sensor arrangement-based probe for the measurement of slots and bore sides with the help of a mirror attachment. The analysis shows the feasibility and limits of the solution with respect to the maximum measurement depth and surface distance measurement working range. We propose two possible solutions: one for maximizing the ratio of the measurement depth to the measured bore size and the second for maximizing the total depth, intended for the measurement of slots and large bore sizes. We analyzed measurement error sources. We found that the errors related to the reflection mirror misalignment can be fully compensated. We proved the validity of the proposed solution with the realization of a commercial laser triangulation sensor-based probe and demonstrated a slot side and a bore side surface distance scanning measurement. The probe working range was assessed with regard to the obscuration effect of optical beams.

• Klíčová slova
• beam, diffraction, distance measurement, edge, hole, laser triangulation, mirror, slot,
• Publikační typ
• časopisecké články MeSH

Mouth-to-microphone (MTM) distance is important when measuring the sound of voice. However, determining the MTM distance for laryngoscope-mounted microphones during laryngoscopic examinations is cumbersome. We introduce a novel solution for such cases, using the depth of insertion of the laryngoscope into the mouth DI as a reference distance. We measured the average insertion depth, DI, in 60 adult women and 60 adult men for rigid laryngoscopes with 70° and 90° view. We found the DI for the 70°/90° laryngoscope to be 9.7 ± 0.9/9.4 ± 0.6 cm in men, 8.9 ± 0.9/8.7 ± 0.7 cm in women, and 9.3 ± 0.9/9.0 ± 0.7 cm in all adults. Using these values, we show that, for microphones fixed at 15-40 cm from the tip of the laryngoscope, the final MTM distances are between 5 and 35 cm from the lips, and the standard uncertainties of these distances are between 16% and 2.5%. Our solution allows laryngologists and laryngoscope manufacturers to set and estimate the MTM distance for any rigid laryngeal endoscope with a microphone attached with reasonable accuracy, avoiding the need to measure this distance in vivo in routine practice.

• Klíčová slova
• mouth-to-microphone distance, oral cavity length, rigid laryngoscopy, voice recording,
• Publikační typ
• časopisecké články MeSH

PURPOSE: Compared to unattended office blood pressure (uOBP), attended office blood pressure (aOBP) is higher. It is not known, however, to what extent distance between physician and patient influences blood pressure (BP) values. MATERIALS AND METHODS: Participants were stable hypertensive patients, followed in the university hospital-based out-patient center. During a session, automated office BP was measured three times after a pre-set five-minute pause, using the Omron 907 device; both aOBP and uOBP were done, in a random order. Simultaneously, beat-to-beat BP measurement was performed using the Finapress device. During aOBP, some participants were in close contact with the physician while others were in loose contact where the doctor was sitting in the room about 2.5 m apart. One year later, the second session with the same protocol was organized, but the close and loose contact were interchanged. The data were analyzed using a paired t-test. RESULTS: Complete data were collected in 32 patients, baseline uOBP was 122.8 ± 14.8/69.5 ± 11.7 mmHg. Systolic and diastolic aOBP with close contact was higher by 4.6 ± 6.9 and 1.9 ± 3.4 mmHg (p < 0.0007 and 0.0039, respectively), while aOBP with loose contact was not different from uOBP. Beat-to-beat BP increased during aOBP by 6.5 ± 8.5/3.3 ± 4.8 mmHg. The increase persisted during all the three aOBP measurements (p < 0.0001 for all systolic and diastolic BP values); the results were similar for close and loose contact. The peak increase during uOBP was of similar magnitude as during aOBP but it lasted shorter: it reached the significance level of p < 0.0001 only during the first uOBP measurement. CONCLUSIONS: Compared to uOBP, aOBP values were higher with close, but not with loose contact between physician and patient. These differences were, however, not detected by beat-to-beat BP measurement.

• Klíčová slova
• Blood pressure measurement, attended office blood pressure, beat-to-beat BP measurement, unattended office blood pressure,
• MeSH
• ambulantní monitorování krevního tlaku metody   MeSH
• automatizace MeSH
• hypertenze * diagnóza   MeSH
• krevní tlak MeSH
• lékaři * MeSH
• lidé MeSH
• měření krevního tlaku metody   MeSH
• systolické šelesty * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

In modern industrial geodesy, high demands are placed on the final accuracy, with expectations currently falling below 1 mm. The measurement methodology and surveying instruments used have to be adjusted to meet these stringent requirements, especially the total stations as the most often used instruments. A standard deviation of the measured distance is the accuracy parameter, commonly between 1 and 2 mm. This parameter is often discussed in conjunction with the determination of the real accuracy of measurements at very short distances (5-50 m) because it is generally known that this accuracy cannot be increased by simply repeating the measurement because a considerable part of the error is systematic. This article describes the detailed testing of electronic distance meters to determine the absolute size of their systematic errors, their stability over time, their repeatability and the real accuracy of their distance measurement. Twenty instruments (total stations) have been tested, and more than 60,000 distances in total were measured to determine the accuracy and precision parameters of the distance meters. Based on the experiments' results, calibration procedures were designed, including a special correction function for each instrument, whose usage reduces the standard deviation of the measurement of distance by at least 50%.

• Klíčová slova
• EDM, absolute distance, baseline, calibration, forced centring, interferometer, pillar, short distance, standard deviation, systematic error,
• Publikační typ
• časopisecké články MeSH

In this work we present a design of an external optical cavity based on Fabry-Perot etalons applied to a 100 MHz Er-doped fiber optical frequency comb working at 1560 nm to increase its repetition frequency. A Fabry-Perot cavity is constructed based on a transportable cage system with two silver mirrors in plano-concave geometry including the mode-matching lenses, fiber coupled collimation package and detection unit. The system enables full 3D angle mirror tilting and x-y off axis movement as well as distance between the mirrors. We demonstrate the increase of repetition frequency by direct measurement of the beat frequency and spectrally by using the virtually imaged phased array images.

• Publikační typ
• časopisecké články MeSH

We present a fiber-optical sensor for distance measurement of smooth and rough surfaces that is based on white-light interferometry; the sensor measures the distance from the sample surface to the sensor head. Because white light is used, the measurement is absolute. The measurement uncertainty depends not on the aperture of the optical system but only on the properties of the rough surface and is commonly approximately 1 microm. The measurement range is approximately 1 mm. The sensor includes no mechanical moving parts; mechanical movement is replaced by the spectral decomposition of light at the interferometer output. The absence of mechanical moving parts enables a high measuring rate to be reached.

• Publikační typ
• časopisecké články MeSH