Spatial monitoring of flying insects over a Swedish lake using a continuous-wave lidar system.

We have used a continuous-wave bi-static lidar system based on the Scheimpflug principle in measurements on flying insects above, and in the vicinity of, a small lake located in a forested area in Southern Sweden. The system, which operates on triangulation principles, has a high spatial resolution at close distance, followed by a subsequent decline in resolution further from the sensor, related to the compact system design with a separation of transmitter and receiver by only 0.81 m.

Perspectives on interstitial photodynamic therapy for malignant tumors.

Significance: Despite remarkable advances in the core modalities used in combating cancer, malignant diseases remain the second largest cause of death globally. Interstitial photodynamic therapy (IPDT) has emerged as an alternative approach for the treatment of solid tumors.

Aim: The aim of our study is to outline the advancements in IPDT in recent years and provide our vision for the inclusion of IPDT in standard-of-care (SoC) treatment guidelines of specific malignant diseases.

Gas Monitoring in Human Frontal Sinuses-Stability Considerations and Gas Exchange Studies.

Acute rhinosinusitis is a common infectious disease, which, in more than 90% of cases, is caused by viruses rather than by bacteria. Even so, antibiotics are often unnecessarily prescribed, and in the long run this contributes to the alarming level of antibiotics resistance. The reason is that there are no good guiding tools for defining the background reason of the infection.

Identification of Flying Insects in the Spatial, Spectral, and Time Domains with Focus on Mosquito Imaging.

Insects constitute a very important part of the global ecosystem and include pollinators, disease vectors, and agricultural pests, all with pivotal influence on society. Monitoring and control of such insects has high priority, and automatic systems are highly desirable. While capture and analysis by biologists constitute the gold standard in insect identification, optical and laser techniques have the potential for high-speed detection and automatic identification based on shape, spectroscopic properties such as reflectance and fluorescence, as well as wing-beat frequency analysis.

Foreground Scattering Elimination by Inverse Lock-in-Like Spatial Modulation.

We describe a simple approach to enhance vision, which is impaired by close range obscuring and/or scattering structures. Such structures may be found on a dirty windscreen of a car, or by tree branches blocking the vision of objects behind. The main idea is to spatially modulate the obscuration, either by periodically moving the detector/eye or by letting the obscuration modulate itself, such as branches swinging in the wind.

Mercury as a Geophysical Tracer Gas - Emissions from the Emperor Qin Tomb in Xi´an Studied by Laser Radar.

Mercury is, because of its high vapor pressure and its prevalence in the atmosphere as atoms, an interesting geophysical tracer gas, also with potential archaeological applications. According to historical records dating back 2200 years, the mausoleum chamber of the "Terracotta Army Emperor" Qin in Xi´an, China, contains large amounts of liquid mercury, considered as an elixir of life at the time. We here report on measurements of the atmospheric contents of atomic mercury above the tomb mound performed with a mobile differential absorption lidar (light detection and ranging) system.

Short-range remote sensing of water quality by a handheld fluorosensor system.

Laser-induced fluorescence is a powerful measurement method for determining the concentration of organic pollutants as well as the amount of algae in water. It can be applied in remote sensing of natural waters and has the advantages of high speed and sensitivity. In this paper, we present a compact handheld fluorosensor system for water quality assessment.

Ripening of avocado fruits studied by spectroscopic techniques.

Avocados are considered very healthy due to the high content mono-unsaturated lipid, essential vitamins and minerals, minimal sugar and no cholesterol and are therefore sometimes referred to as "the perfect fruits". Avocados, mainly grown in Latin-America, are harvested unripe and sent overseas. However, the ripening process is very difficult to assess visually and tactilely.

Vis/NIR reflectance spectroscopy for hybrid rice variety identification and chlorophyll content evaluation for different nitrogen fertilizer levels.

Nitrogen is one of the most important nutrient indicators for the growth of crops, and is closely related to the chlorophyll content of leaves and thus influences the photosynthetic ability of the crops. In this study, five hybrid rice varieties were cultivated during one entire growing period in one experimental field supplied with six nitrogen fertilizer levels. Visible and near infrared (vis/NIR) reflectance spectroscopy combined with multivariate analysis was used to identify hybrid rice varieties and nitrogen fertilizer levels, as well as to detect chlorophyll content associated with nitrogen levels.

Laser-based gas absorption spectroscopy in decaying hip bone: water vapor as a predictor of osteonecrosis.

Affluent blood flow through a complicated net of vessels supplies skeletal bone tissue with oxygen and nutrients. Due to accidental events or physiological processes, the blood supply might be deficient or even disrupted, and the healthy bone decays in a process that, for the hip location, is denoted as osteonecrosis of the femoral head (ONFH) or avascular femoral head necrosis. Early diagnosis is important for the prognosis.

Non-intrusive studies of gas contents and gas diffusion in hen eggs.

A detailed study of the condition of eggs was performed using tunable diode lasers to monitor free gas in hen eggs. We detected oxygen and water vapor signals from 13 unfertilized eggs and studied the growth of the egg air cell over a time period of 3 weeks. We also studied the gas exchange through the egg shell, which is of particular interest for fertilized eggs.

Towards an optical diagnostic system for otitis media using a combination of otoscopy and spectroscopy.

An improved method, where conventional otoscope investigation of human suspicious otitis media is combined with diffuse reflectance spectroscopy and gas in scattering media absorption spectroscopy (GASMAS) is being developed. Otitis media is one of the most common infectious diseases in children, whose Eustachian tube connecting the middle ear with the nasal cavity is more horizontal than for adults, which leads to impaired fluid drainage. At present, the use of an otoscope to visually observe possible changes in the tympanic membrane appearance is the main diagnostics method for otitis media.

Particle profiling and classification by a dual-band continuous-wave lidar system.

A dual-band continuous-wave (CW) light detection and ranging (lidar) system has been developed for particle classification. In this lidar system, the range-resolved atmospheric backscattering signal is recorded by an optical imaging system satisfying the Scheimpflug principle instead of the conventional time-of-flight approach. It is thus possible to employ low-cost and compact CW diode lasers, facilitating the development of a robust multiple-wavelength atmospheric lidar system that can attain high accuracy of the retrieved parameters of atmospheric particles.

Optical characterization of Chinese hybrid rice using laser-induced fluorescence techniques-laboratory and remote-sensing measurements: publisher's note.

This publisher's note corrects the author listing and a figure caption in Appl. Opt.57, 3481 (2018)APOPAI0003-693510.

The bat-bird-bug battle: daily flight activity of insects and their predators over a rice field revealed by high-resolution Scheimpflug Lidar.

We present the results of, to our knowledge, the first Lidar study applied to continuous and simultaneous monitoring of aerial insects, bats and birds. It illustrates how common patterns of flight activity, e.g.

Lidar mapping of atmospheric atomic mercury in the Wanshan area, China.

A novel mobile laser radar system was used for mapping gaseous atomic mercury (Hg) atmospheric pollution in the Wanshan district, south of Tongren City, Guizhou Province, China. This area is heavily impacted by legacy mercury from now abandoned mining activities. Differential absorption lidar measurements were supplemented by localized point monitoring using a Lumex RA-915M Zeeman modulation mercury analyzer.

Optical characterization of Chinese hybrid rice using laser-induced fluorescence techniques-laboratory and remote-sensing measurements.

Chinese hybrid rice of different varieties, growing in paddies in the Pingqiao district, north of Xinyang city, Henan province, China, was studied in detailed spectroscopic characteristics using laser-induced fluorescence. The base for the studies was the new South China Normal University mobile lidar laboratory, which was dispatched on site, providing facilities both for laboratory studies using a 405 nm excitation source as well as remote sensing measurements at ranges from around 40 m-120 m, mostly employing the 532 nm output from a Nd:YAG laser. We, in particular, studied the spectral influence of the species varieties as well as the level of nitrogen fertilization supplied.

Detection of free oxygen and water vapor in fertilized and unfertilized eggs by diode laser spectroscopy-Exploration of diagnostics possibilities.

Nonintrusive methods for characterizing food products are of increasing interest related to the greater awareness of food safety issues. Hen eggs are an important part in food consumption in most parts of the world. We have investigated an optical method utilizing tunable diode lasers for monitoring free gas in eggs.

Sensitivity enhancement and fringe reduction in tunable diode laser spectroscopy using hemispherical diffusers.

The use of diffuse, highly reflective optical components, in particular, a hemispherical BaSO diffuser, at the point of light injection into non-transparent or turbid media was evaluated as a means to increase the measurement sensitivity of spectroscopic absorption measurements. By performing the light injection from, e.g.

Diagnostics of femoral head status in humans using laser spectroscopy - In vitro studies.

Osteonecrosis of the femoral head (ONFH), a recalcitrant and disabling disease, is caused by inadequate or fully disrupted blood supply to the affected segment of the subchondral bone. Theoretically, there will develop gas-filled pores during the bone decay process due to lacking blood supply. Unfortunately, the relationship between the gas-filled pores and ONFH is still unclear.

Gas exchange in fruits related to skin condition and fruit ripening studied with diode laser spectroscopy.

The concentration of the biologically active molecular oxygen gas is of crucial importance for fruits in the metabolic respiration, maturation, and ripening processes. In our study, oxygen content and oxygen transport in fruits, exemplified by apples and guavas, were studied noninvasively by gas in scattering media absorption spectroscopy. The technique is based on the fact that free gases typically have 10,000 times narrower absorption features than the bulk material.

Application of Tunable Diode Laser Spectroscopy for the Assessment of Food Quality.

Adequate food packaging is important to ensure food quality and prolong the shelf life of food. Frequently, the method of modified atmosphere packaging (MAP) is used. We used a tunable diode laser spectroscopy technique to detect the oxygen content in food packages, e.

Reflectance and fluorescence characterization of maize species using field laboratory measurements and lidar remote sensing.

Laser-induced fluorescence is an important technique to study photosynthesis and plants. Information on chlorophyll and other pigments can be obtained. We have been using a mobile laboratory in a Chinese experimental farm setting to study maize (Zea mays L.

Laser spectroscopy applied to environmental, ecological, food safety, and biomedical research.

Laser spectroscopy provides many possibilities for multi-disciplinary applications in environmental monitoring, in the ecological field, for food safety investigations, and in biomedicine. The paper gives several examples of the power of multi-disciplinary applications of laser spectroscopy as pursued in our research group. The studies utilize mostly similar and widely applicable spectroscopic approaches.

Laser spectroscopic studies of gas diffusion in alumina ceramics.

Experiments for measuring gas diffusion through porous alumina ceramics are described. With the gas in scattering media absorption spectroscopy (GASMAS) technique, gaseous oxygen signals are measured continuously during the gas diffusion process. It is experimentally demonstrated that the time-dependence of the transient oxygen signal is described by an exponential curve.