A new approach to precise 3D topometry for medical applications has been applied for the documentation of cultural heritage. The 3D imaging system works with pulsed holography. With a single pulse of a Nd:YLF laser, a surface is recorded with a holographic camera on photosensitive material. The short exposure time of 35 ns allows for high resolution 3D measurement without movement artefacts. The pulsed technique is robust against vibrations and the latest generation of cameras is portable and works at daylight. The holograms are digitized in a second selfcontained unit where the projections of the optically reconstructed real image of the hologram are recorded. Numerical data processing leads to a 3D computer model of the surface with intrinsic gray scale texture. In addition, full-scale daylight copies of the master hologram give an impressive detailed 3D view of the recorded object. The technique is used for 3D imaging of the Windeby Child bog body.

The diffusion of NaH molecules in H2 gas and its reactive loss mechanism are described. The temporal behaviour of photochemically produced NaH in the reactive Na(3p)-H2(v″ = 2;3) collision system was observed by means of resonant coherent anti-Stokes Raman scattering (RECARS). A simple diffusion model, presented in this article, applies well in the lower pressure region (0 mbar). The binary diffusion constant for NaH molecules in H2, D0 = 0:7 cm2/s at 1 atm and 273 K, was determined. At higher pressures (up to 900 mbar), where the influence of diffusion decreased, an unexpectedly rapid decay of the NaH signal is observed. From this time behaviour we identify a new NaH loss mechanism and shown for the first time by means of time resolved CARS that this reaction can be described by a second-order rate equation in NaH.

Laser-spectrometric methods to derive absolute and traceable carbon monoxide (CO) amount fractions in exhaled human breath could be of advantage for early disease detection as well as for treatment monitoring. As proof-of-principle laboratory experiment, we employed intra-pulse and continuous wave (cw) quantum cascade laser spectroscopy (QCLAS), both at 4.6 μ m. Additional experiments were carried out applying cw cavity ring-down spectroscopy (CRDS) with a CO sideband laser and a QCL. We emphasize metrological data quality objectives, thatis, traceability and uncertainty, which could serve as essential benefits to exhaled breath measurements. The results were evaluated and compared on a 100 μ mol/mol CO level using the two QCLAS spectrometers, and the cw CO sideband laser CRDS setup. The relative standard uncertainties of the pulsed and the cw QCLAS CO amount fraction results were ±4.8 and ±2.8%, respectively, that from the CO sideband laser CRDS was ±2.7%. Sensitivities down to a 3 nmol/mol CO level were finally demonstrated and quantified by means of cw CRDS equipped with a QCL yielding standard uncertainties of about ±2.5 that are exclusively limited by the available line strength figure quality. With this study we demonstrate the achieved comparability of CO quantifications, adhering metrological principles.

The aim of the study was to compare the histological results after complete osteotomies of the sheep tibia using either the prototype carbon dioxide (CO2) laser osteotome ‘OsteoLAS’ (n = 12) or an oscillating saw (n = 12). The laser parameters were as follows: wavelength 10.6 µm; energy of laser pulses 75–85 mJ; pulse duration 80 μs; pulse repetition rate 200 Hz; spot diameter 460 μm (1/e2 level); radiant exposure 45–51 J/cm2; peak irradiance 0.56–0.64 MW/cm2. Both groups were divided into two subgroups (n = 6), and the animals were killed after 4 weeks or 12 weeks, respectively. Light and fluorescence microscopy with semiquantitative analysis and histomorphometry were performed to compare bone healing. Charring-free laser osteotomies were possible up to a depth of 20 mm with the short-pulsed CO2 laser. The laser, however, required a significantly longer time to perform, and a wedge-shaped gap was present on the cis-cortex. After 4 weeks the osteotomy gaps were almost unchanged in both groups and filled with connective tissue. After 12 weeks the gaps were filled with newly formed bone in both groups. Primary gap healing was predominant in the laser group and longitudinal cortical remodelling in the control group. On a cellular level, no fundamental differences were observed for early and late stages of bone healing. Further research has to be focussed on improving the CO2 laser ostetome in order to reduce the long duration of the laser osteotomy and the necessity of creating a wedge-shaped cut in thick bones.

For medical applications, erbium lasers are usually equipped with articulated mirror arms or special glass fibers. However, only with mirror arms is it so far possible to transmit high average powers or pulse energies in the region of 1 J to achieve suitable energy densities for fast tissue preparation. An alternative to the glass fiber systems mentioned above are liquid-core light guides. An extremely flexible liquid-core light guide was used to connect a dental Er:YAG laser system to an especially adapted dental laser applicator. The core liquid was continuously circulated during laser irradiation to transmit pulse energies up to 1.1 J. A modified laser handpiece was used for exemplary clinical treatment. The experimental setup with the highly flexible light guide was completed successfully, and its ease of handling for a dental surgeon was demonstrated in the clinical treatment of leukoplakia of the oral cheek mucosa. Complete ablation of the epithelium with the laser was performed. One year postoperatively, the patient remains disease-free. This article describes the technical realization of a liquid-core light guide system for medical applications. We report about the first successful clinical treatment of oral hyperkeratosis using this new light guide technology.

This chapter contains sections titled: Introduction Trace Gases in Medicine and Biology Instrumentation for Laser Analytics of Breath and Other Biological Gas Samples Applications to Life Sciences Conclusion and Perspectives Acknowledgements References

Our aim is the development of a method for determining the total hemoglobin mass with a noninvasive method using Cavity Leak-Out Spectroscopy in the mid-infrared region. A possible application would be detection of blood doping.

Carbon monoxide (CO) detection in human breath is the focus of much research because of CO's possible use as a marker molecule for different diseases. Detecting CO in human breath remains a tough challenge because of the low concentrations of CO (ppm range) that must be detected. Another problem is that many other molecules, which can be found in human breath, can interfere in these measurements. Additionally, a time resolution of less than 1 s is needed to resolve the CO curve of an exhalation. In this study 13CO instead of 12CO concentration is measured. The measurements are performed with a cavity leak-out spectroscopy system. The system's properties match the above-mentioned specifications for measurements, even of the rare isotopologue with high specificity, a time resolution of less than 1 s and a detection limit of 7 ppb Hz−1/2. Two investigations are presented here. The first is a measurement showing intraday changes between 9.5% and 23.3% of the exhaled CO level due to vigorous exercise. The second shows a long-term observation of the CO base level revealing natural variations in the recorded CO concentration. The covered time period is 25 weeks during which the differences between the minimum and maximum CO levels for each test case reached 84%.

A precise cochleostomy is a crucial step in cochlear implantation, particularly if residual hearing is to be preserved. A contactless ablation of the promontory bone by a pulsed CO(2) laser system seems to be a promising approach. The bone is removed by a scan head controlled laser beam in sequential scan cycles with a pulse rate of 50-100 mus. Digital picture analysis and pattern detection are used to identify the membranous lining of the cochlea. We achieved a bone ablation in a micrometer range per scan cycle with the laser. A perforation of the promontory bone could be detected by automatic pattern detection. The enhancement of automatic pattern detection can lead to a minimally invasive, function-preserving laser cochleostomy.

We report on monitoring of nitric oxide (NO) traces in human breath via infrared cavity leak-out spectroscopy. Using a CO sideband laser near 5 μm wavelength and an optical cavity with two high-reflectivity mirrors (R=99.98%), the minimum detectable absorption is 2×10−10 cm−1 Hz1/2. This allows for spectroscopic analysis of rare NO isotopologues with unprecedented sensitivity. Application to simultaneous online detection of 14NO and 15NO in breath samples collected in the nasal cavity is described for the first time. We achieved a noise-equivalent detection limit of 7 parts per trillion for nasal 15NO (integration time: 70 s).

We report on monitoring of nitric oxide (NO) traces in human breath via infrared cavity leak-out spectroscopy. Using a CO sideband laser near 5 mu m wavelength and an optical cavity with two high-reflectivity mirrors (R=99.98%), the minimum detectable absorption is 2x10(-10) cm(-1) Hz(1/2). This allows for spectroscopic analysis of rare NO isotopologues with unprecedented sensitivity. Application to simultaneous online detection of (NO)-N-14 and (NO)-N-15 in breath samples collected in the nasal cavity is described for the first time. We achieved a noise-equivalent detection limit of 7 parts per trillion for nasal (NO)-N-15 (integration time: 70 s).

We describe a technique of simultaneous detection of 14NO and 15NO by means of Faraday Modulation Spectroscopy (FAMOS) based on a cw distributed feedback quantum cascade laser (QCL) operating near 5.4 μm. FAMOS is a spectroscopic method for selective, sensitive, and time-resolved detection of free radical molecules such as NO, in the mid-infrared spectral region. The selected spectral lines are the Q (1.5) for 15NO located at 1842.76 cm−1 and the P (9.5) for 14NO located at 1842.93 cm−1. The detection limit (1σ) of 6 ppb\(/\sqrt{\mathrm{Hz}}\) for 15NO and 62 ppb\(/\sqrt{\mathrm{Hz}}\) for 14NO has been achieved. The simultaneous detection was performed using a fast laser frequency switching between the two isotopologues with a time resolution of 2 s. The isotope ratio (δ 15N) has been determined with a precision (1σ) of 0.52‰ at 800-s averaging time for 100 ppm NO-gas with a time resolution of 2 s. δ 15N is determined after NO release from nitrite by chemical reduction with potassium iodine.

Facial reconstruction can be used as a forensic technique to identify a person, when no other identification method is applicable. The facial soft tissue thickness applied to the skull is crucial when performing an accurate facial reconstruction. Historically, scientists developed several techniques to measure the soft tissue of the face. It was their aim, to build a database of a unique point-set, differentiated by gender, age, ethnic origin, BMI. All used a limited number of landmarks and an inaccurate measuring technique. We developed a contact-free and precise measuring technique, using low-dose CT and holographic data. Due to the extremely short exposure time, the holographic measurement is very precise. We lay out our first experiences to create a facial soft tissue layer map of the face.

Cavity Leak-Out Spectroscopy is a potent method to detect NO and CO from breath and blood which doesn't need to fear the comparison to gold standard techniques. Applications of this technique are discussed. Article not available.

Comparison of two different methods for the measurement of ethane at the parts-per-billion (ppb) level is reported. We used cavity leak-out spectroscopy (CALOS) in the 3 microm wavelength region and gas chromatography-flame ionization detection (GC-FID) for the analysis of various gas samples containing ethane fractions in synthetic air. Intraday and interday reproducibilities were studied. Intercomparing the results of two series involving seven samples with ethane mixing ratios ranging from 0.5 to 100 ppb, we found a reasonable agreement between both methods. The scatter plot of GC-FID data versus CALOS data yields a linear regression slope of 1.07 +/- 0.03. Furthermore, some of the ethane mixtures were checked over the course of 1 year, which proved the long-term stability of the ethane mixing ratio. We conclude that CALOS shows equivalent ethane analysis precision compared to GC-FID, with the significant advantage of a much higher time resolution (<1 s) since there is no requirement for sample preconcentration. This opens new analytical possibilities, e.g., for real-time monitoring of ethane traces in exhaled human breath.

The aim of this study is a defined, visually based and camera controlled bone removal by a navigated CO2 laser on the promontory of the inner ear. A precise and minimally traumatic opening procedure of the cochlea for the implantation of a cochlear implant electrode (so-called cochleostomy) is intended. Harming the membrane linings of the inner ear can result in damage of remaining organ functions (e.g. complete deafness or vertigo). A precise tissue removal by a laser-based bone ablation system is investigated. Inside the borehole the pulsed laser beam is guided automatically over the bone by using a two mirror galvanometric scanner. The ablation process is controlled by visual servoing. For the detection of the boundary layers of the inner ear the ablation area is monitored by a color camera. The acquired pictures are analyzed by image processing. The results of this analysis are used to control the process of laser ablation. This publication describes the complete system including image processing algorithms and the concept for the resulting distribution of single laser pulses. The system has been tested on human cochleae in ex-vivo studies. Further developments could lead to safe intraoperative openings of the cochlea by a robot based surgical laser instrument.

Magnetic rotation spectroscopy signals of the nitric oxide (NO) fundamental band near 5 μm have been observed and compared with calculated signals. This spectroscopic approach exploits magnetic field modulation in the Faraday configuration for very sensitive detection of NO. Line shapes and strengths of the Faraday signals depend on molecular parameters, like J and Ω quantum numbers of the transitions involved, and on experimental parameters, like pressure of the gas sample and applied external magnetic field strength. In this study we implemented a software model which provides a simulation of the complete v=1–0 Faraday spectrum of NO. The algorithm considers the magnetic field modulation, the collisional and Doppler broadening of the line shapes, and the line intensities of 14NO and 15NO fundamental band lines. Optimum values for pressure and magnetic field modulation for maximum sensitivity are given. Suitable spectral windows for simultaneous detection of 14NO and 15NO are discussed. Experimental data were obtained in the wavenumber region from 1840 to 1900 cm−1 by means of a CO sideband laser and a quantum cascade laser. Comparison between calculated and observed signals shows excellent agreement.