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1.
Animals (Basel) ; 14(8)2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38672343

RESUMO

Nosema ceranae, a microsporidian parasite, as one of the stressors that contribute to honey bee decline, has a significant negative impact on the longevity, productivity, and reproductive capacity of honey bee colonies. There are several different strategies for Nosema infection control, including natural-based and antibiotic-based products. In this study, we tested wormwood and oak bark-based supplement "Medenko forte" on survival, Nosema infection, oxidative stress, and expression of immune-related genes in artificially N. ceranae-infected bees. The results revealed a positive influence on the survival of Nosema-infected bees, irrespectively of the moment of supplement application (day 1, day 3, or day 6 after bee emergence), as well as reduction of Nosema loads and, consequently, Nosema-induced oxidative stress. Supplementation had no negative effects on bee immunity, but better anti-Nosema than immune-stimulating effects were affirmed based on expression levels of abaecin, defensin, hymenoptaecin, apidaecin, and vitellogenin genes. In conclusion, the tested supplement "Medenko forte" has great potential in the health protection of Nosema-infected bees. However, further investigations need to be performed to elucidate its mechanisms of action.

2.
Animals (Basel) ; 13(22)2023 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-38003159

RESUMO

One of the most important approaches in the prevention and treatment of nosemosis is the use of herbal preparations as food supplements for bees. Therefore, the aim of this study was to investigate the effects of a plant-based supplement branded as "B+" on honeybees in a laboratory experiment. Four experimental groups were established: treated group (T), N. ceranae-infected and treated group (IT), N. ceranae-infected group (I) and non-infected group (NI). Survival, N. ceranae spore load and oxidative stress parameters together with expression levels of antioxidant enzyme genes and vitellogenin gene were monitored. The mortality in the T, IT and NI groups was significantly (p < 0.001) lower than in than in the I group. Within Nosema-infected groups, the IT group had a significantly lower (p < 0.001) number of N. ceranae spores than the I group. In addition, expression levels of genes for antioxidant enzymes were lower (p < 0.001) in the IT group compared to the I group. The concentration of malondialdehyde and the activities of antioxidant enzymes (superoxide dismutase, catalase and glutathione S-transferase) were significantly lower (p < 0.001) in the IT group compared to the I group. No negative effects of the tested supplement were observed. All these findings indicate that the tested supplement exerted beneficial effects manifested in better bee survival, reduced N. ceranae spore number and reduced oxidative stress of bees (lower expression of genes for antioxidant enzymes and oxidative stress parameters).

3.
Science ; 380(6641): 198-203, 2023 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-37053312

RESUMO

Direct imaging of gas giant exoplanets provides information on their atmospheres and the architectures of planetary systems. However, few planets have been detected in blind surveys with direct imaging. Using astrometry from the Gaia and Hipparcos spacecraft, we identified dynamical evidence for a gas giant planet around the nearby star HIP 99770. We confirmed the detection of this planet with direct imaging using the Subaru Coronagraphic Extreme Adaptive Optics instrument. The planet, HIP 99770 b, orbits 17 astronomical units from its host star, receiving an amount of light similar to that reaching Jupiter. Its dynamical mass is 13.9 to 16.1 Jupiter masses. The planet-to-star mass ratio [(7 to 8) × 10-3] is similar to that of other directly imaged planets. The planet's atmospheric spectrum indicates an older, less cloudy analog of the previously imaged exoplanets around HR 8799.

4.
Artigo em Inglês | MEDLINE | ID: mdl-36240662

RESUMO

Malignant ovine babesiosis or ovine babesiosis caused by Babesia ovis is an important hemoprotozoan tick-borne disease of sheep. After 70 years, a study was conducted in Bosnia and Herzegovina, in the geographical areas of Podrinje and Eastern Herzegovina, aiming to molecularly identify and determine the presence of B. ovis infection in the sheep population. From 2019-2021, a clinical and molecular study was conducted in 53 flocks, and 192 sheep were examined, divided into two groups: clinically suspected and asymptomatic sheep. The presence of B. ovis was confirmed by PCR in blood samples of 75 % and 11.21 % of clinically affected and asymptomatic sheep, respectively. The majority of clinical cases of malignant ovine babesiosis were confirmed in the Rudo epidemiological unit (78.78 %) within the Podrinje region indicating typical seasonal pattern of disease occurrence and endemic focus. Rhipicephalus bursa was only tick species identified in Podrinje and Eastern Herzegovina. Acute form of disease was observed with dominant clinical signs of depression, fever, loss of appetite and respiratory distress. Fatal outcome was recorded in 12.28 % of cases. This study describes the molecular detection of B. ovis in sheep in Bosnia and Herzegovina for the first time. To the authors knowledge, this survey represents a report of the highest number of clinical cases of malignant ovine babesiosis in Europe. Since the disease has been recorded in the south-eastern border of Bosnia and Herzegovina, there is a high risk of disease transmission to a wider area of the Balkan region.


Assuntos
Babesiose , Rhipicephalus , Doenças dos Ovinos , Ovinos , Animais , Babesiose/epidemiologia , Babesiose/diagnóstico , Bósnia e Herzegóvina/epidemiologia , Península Balcânica
5.
Opt Express ; 30(20): 36745-36760, 2022 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-36258597

RESUMO

Spectral shaping is critical to many fields of science. In astronomy for example, the detection of exoplanets via the Doppler effect hinges on the ability to calibrate a high resolution spectrograph. Laser frequency combs can be used for this, but the wildly varying intensity across the spectrum can make it impossible to optimally utilize the entire comb, leading to a reduced overall precision of calibration. To circumvent this, astronomical applications of laser frequency combs rely on a bulk optic setup which can flatten the output spectrum before sending it to the spectrograph. Such flatteners require complex and expensive optical elements like spatial light modulators and have non-negligible bench top footprints. Here we present an alternative in the form of an all-photonic spectral shaper that can be used to flatten the spectrum of a laser frequency comb. The device consists of a circuit etched into a silicon nitride wafer that supports an arrayed-waveguide grating to disperse the light over hundreds of nanometers in wavelength, followed by Mach-Zehnder interferometers to control the amplitude of each channel, thermo-optic phase modulators to phase the channels and a second arrayed-waveguide grating to recombine the spectrum. The demonstrator device operates from 1400 to 1800 nm (covering the astronomical H band), with twenty 20 nm wide channels. The device allows for nearly 40 dBs of dynamic modulation of the spectrum via the Mach-Zehnders , which is greater than that offered by most spatial light modulators. With a smooth spectrum light source (superluminescent diode), we reduced the static spectral variation to ∼3 dB, limited by the properties of the components used in the circuit. On a laser frequency comb which had strong spectral modulations, and some at high spatial frequencies, we nevertheless managed to reduce the modulation to ∼5 dBs, sufficient for astronomical applications. The size of the device is of the order of a US quarter, significantly cheaper than their bulk optic counter parts and will be beneficial to any area of science that requires spectral shaping over a broad range, with high dynamic range, including exoplanet detection.

6.
Front Physiol ; 13: 1000944, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36171978

RESUMO

With an almost global distribution, Varroa destuctor is the leading cause of weakening and loss of honey bee colonies. New substances are constantly being tested in order to find those that will exhibit high anti-Varroa efficacy at low doses/concentrations, without unwanted effects on bees. Lithium (Li) salts stood out as candidates based on previous research. The aims of this study were to evaluate Li citrate hydrate (Li-cit) for its contact efficacy against Varroa, but also the effect of Li-cit on honey bees by estimating loads of honey bee viruses, expression levels of immune-related genes and genes for antioxidative enzymes and oxidative stress parameters on two sampling occasions, before the treatment and after the treatment. Our experiment was performed on four groups, each consisting of seven colonies. Two groups were treated with the test compound, one receiving 5 mM and the other 10 mM of Li-cit; the third received oxalic acid treatment (OA group) and served as positive control, and the fourth was negative control (C group), treated with 50% w/v pure sucrose-water syrup. Single trickling treatment was applied in all groups. Both tested concentrations of Li-cit, 5 and 10 mM, expressed high varroacidal efficacy, 96.85% and 96.80%, respectively. Load of Chronic Bee Paralysis Virus significantly decreased (p < 0.01) after the treatment in group treated with 5 mM of Li-cit. In OA group, loads of Acute Bee Paralysis Virus and Deformed Wing Virus significantly (p < 0.05) increased, and in C group, loads of all viruses significantly (p < 0.01 or p < 0.001) increased. Transcript levels of genes for abaecin, apidaecin, defensin and vitellogenin were significantly higher (p < 0.05-p < 0.001), while all oxidative stress parameters were significantly lower (p < 0.05-p < 0.001) after the treatment in both groups treated with Li-cit. All presented results along with easy application indicate benefits of topical Li-cit treatment and complete the mosaic of evidence on the advantages of this salt in the control of Varroa.

7.
Front Vet Sci ; 8: 678880, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34532351

RESUMO

Native goat breeds in Serbia has been recognized as an important element of regional agrobiodiversity and play an important role in the safeguarding of cultural and traditional heritage. The aim of this study was to identify the main welfare issues likely to be encountered in extensive goat farming systems with an emphasis on parasitological infections. The study was conducted during the winter season on four small farms of native Balkan and Serbian white goats. For welfare assessment, animal-based indicators from AWIN protocol for goats were used. All fecal samples for parasites were qualitatively and quantitatively examined. The main welfare issues identified were poor hair coat condition (62.79%), dirty and light soiling hindquarters (31.40%), thin body condition score (26.74%), abscesses (19.78%), and udder asymmetry (18.60%). In addition, an important and prevalent welfare problem identified across all farms was parasite infection and weak significant (p < 0.001) correlation between certain parasites (Strongylidae, Moniezia spp., Buxtonella sulcate, and Protostrongylidae) and welfare indicators such as poor hair coat condition and nasal discharge. The results of this study provided the first overview and valuable insight into the impact of extensive systems on the welfare of native goats in the Balcan region.

8.
Appl Opt ; 60(19): D15-D32, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34263825

RESUMO

Integrated photonic spectrographs offer an avenue to extreme miniaturization of astronomical instruments, which would greatly benefit extremely large telescopes and future space missions. These devices first require optimization for astronomical applications, which includes design, fabrication, and field testing. Given the high costs of photonic fabrication, multi-project wafer (MPW) silicon nitride (SiN) offerings, where a user purchases a portion of a wafer, provide a convenient and affordable avenue to develop this technology. In this work, we study the potential of two commonly used SiN waveguide geometries by MPW foundries, i.e., square and rectangular profiles, to determine how they affect the performance of mid/high-resolution arrayed waveguide grating (AWG) spectrometers around 1.5 µm. Specifically, we present results from detailed simulations on the mode sizes, shapes, and polarization properties, and on the impact of phase errors on the throughput and cross talk as well as some laboratory results of coupling and propagation losses. From the MPW run tolerances and our phase-error study, we estimate that an AWG with R ∼10,000 can be developed with the MPW runs, and even greater resolving power is achievable with more reliable, dedicated fabrication runs. Depending on the fabrication and design optimizations, it is possible to achieve throughputs ∼60% using the SiN platform. Thus, we show that SiN MPW offerings are highly promising and will play a key role in integrated photonic spectrograph developments for astronomy.

9.
Appl Opt ; 60(19): D33-D42, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34263826

RESUMO

One key advantage of single-mode photonic technologies for interferometric use is their ability to easily scale to an ever-increasing number of inputs without a major increase in the overall device size, compared to traditional bulk optics. This is particularly important for the upcoming extremely large telescope (ELT) generation of telescopes currently under construction. We demonstrate the fabrication and characterization of a hybridized photonic interferometer, with eight simultaneous inputs, forming 28 baselines, which is the largest amount to date, to the best of our knowledge. Using different photonic fabrication technologies, we combine a 3D pupil remapper with a planar eight-port ABCD pairwise beam combiner, along with the injection optics necessary for telescope use, into a single integrated monolithic device. We successfully realized a combined device called Dragonfly, which demonstrates a raw instrumental closure-phase stability down to 0.9° over $8\pi$ phase piston error, relating to a detection contrast of ${\sim}6.5 \times {10^{- 4}}$ on an adaptive-optics-corrected 8 m telescope. This prototype successfully demonstrates advanced hybridization and packaging techniques necessary for on-sky use for high-contrast detection at small inner working angles, ideally complementing what can currently be achieved using coronagraphs.

10.
Appl Opt ; 60(19): D108-D121, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34263844

RESUMO

By combining integral field spectroscopy with extreme adaptive optics, we are now able to resolve objects close to the diffraction limit of large telescopes, exploring new science cases. We introduce an integral field unit designed to couple light with a minimal plate scale from the SCExAO facility at NIR wavelengths to a single-mode spectrograph. The integral field unit has a 3D-printed micro-lens array on top of a custom single-mode multi-core fiber, to optimize the coupling of light into the fiber cores. We demonstrate the potential of the instrument via initial results from the first on-sky runs at the 8.2 m Subaru Telescope with a spectrograph using off-the-shelf optics, allowing for rapid development with low cost.

11.
Nat Commun ; 12(1): 2465, 2021 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-33927206

RESUMO

Characterisation of exoplanets is key to understanding their formation, composition and potential for life. Nulling interferometry, combined with extreme adaptive optics, is among the most promising techniques to advance this goal. We present an integrated-optic nuller whose design is directly scalable to future science-ready interferometric nullers: the Guided-Light Interferometric Nulling Technology, deployed at the Subaru Telescope. It combines four beams and delivers spatial and spectral information. We demonstrate the capability of the instrument, achieving a null depth better than 10-3 with a precision of 10-4 for all baselines, in laboratory conditions with simulated seeing applied. On sky, the instrument delivered angular diameter measurements of stars that were 2.5 times smaller than the diffraction limit of the telescope. These successes pave the way for future design enhancements: scaling to more baselines, improved photonic component and handling low-order atmospheric aberration within the instrument, all of which will contribute to enhance sensitivity and precision.

12.
Prev Vet Med ; 190: 105322, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33744676

RESUMO

It is common knowledge that nutritive stress resulting from decreased diversity and quality of food, pollution of food sources and beekeeping errors may lead to increased susceptibility of bees to pathogens and pesticides. The dearth of adequate food is frequently compensated with supplements. Thus, this research was aimed to study the effects of the plant-based supplement B + on colony strength (assessed according to open and sealed brood area, honey and pollen/bee bread reserves, and the number of adult bees). In addition, Nosema ceranae spores and viruses were quantified and the level of infestation with Varroa destructor assessed. The experiment was conducted in late summer and early spring. In colonies which were given B + in feed a significant increase (p < 0.05) in the parameters of colony strength were noticed in comparison to the control (colonies fed on sugar syrup). Moreover, it was proven that the bees from these colonies had significantly lower (p < 0.05) N. ceranae spore counts, and acute bee paralysis, deformed wing and sacbrood virus loads. Our results suggest that the addition of B + supplement to the colonies provide them with nutrients, contribute to their strengthening, might prevent nutritive stress and increase the success of bees in combating pathogens.


Assuntos
Criação de Abelhas , Dieta/veterinária , Microsporidiose/veterinária , Infestações por Ácaros/veterinária , Complexo Vitamínico B/administração & dosagem , Animais , Abelhas , Microsporidiose/prevenção & controle , Infestações por Ácaros/prevenção & controle , Nosema , Varroidae , Vitaminas
13.
Opt Lett ; 44(9): 2204-2207, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31042184

RESUMO

Vortex fiber nulling is a method for spectroscopically characterizing exoplanets at small angular separations, ≲λ/D, from their host star. The starlight is suppressed by creating an optical vortex in the system point spread function, which prevents the stellar field from coupling into the fundamental mode of a single-mode optical fiber. Light from the planet, on the other hand, couples into the fiber and is routed to a spectrograph. Using a prototype vortex fiber nuller (VFN) designed for monochromatic light, we demonstrate coupling fractions of 6×10-5 and >0.1 for the star and planet, respectively.

14.
J Invertebr Pathol ; 151: 76-81, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29113738

RESUMO

A recently described trypanosomatid species Lotmaria passim and the microsporidium Nosema ceranae infect the honey bee (Apis mellifera), but the interspecific dynamic of these two common gut parasites is unknown. In this study, a real-time qPCR assay was developed to enable the specific detection and quantification of L. passim. The annual dynamics of N. ceranae and L. passim infections were evaluated in ten A. mellifera colonies naturally infected with both parasites at one apiary in Serbia from March 2016 to March 2017. Ten samples (60 bees abdomens) were taken from each colony on 8 sampling occasions. L. passim infection level was evaluated with qPCR, while N. ceranae infection was measured by spore counts. N. ceranae infection level was significantly higher in comparison with that of L. passim (spore or cell equivalents/bee, respectively). Significant positive correlation between infection levels of the parasite species indicates their similar annual dynamics, whilst the differences in the levels of infection between particular months point to a seasonal pattern in the incidence of both parasites. The assay which has been developed and validated creates opportunity for detailed study of L. passim infection kinetics and the improvement in the management practices in beekeeping related to these two parasites.


Assuntos
Abelhas/parasitologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Trypanosomatina/fisiologia , Animais , DNA Fúngico/análise , DNA de Protozoário/análise , Nosema
15.
Vasc Endovascular Surg ; 51(7): 501-505, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28764607

RESUMO

We present a patient with blunt abdominal trauma with severe acute right limb ischemia and clinical signs of diffuse peritonitis. Computed tomography angiography showed circumferential dissection of the infrarenal aorta with occlusion of the right common iliac artery. We opted for simultaneous abdomen exploration and open repair of injured aorta. Critical weakening of the aortic wall with imminent rupture was identified intraoperatively. Aortotomy cranially from bifurcation showed circumferential intimomedial dissection. The fixation of fragile intimomedial flap of aortic dissection was achieved with reinforcement using an anterior longitudinal ligament. The long aortoiliac arteriotomy was repaired using a great saphenous vein patch. Patient had uneventful postoperative course and was discharged after 7 days. In patients with abdominal polytrauma with peritonitis, and no available endovascular tools, open surgery for circumferential aortic dissection is possible and successful. Described reinforcement of the posterior aortic wall to the anterior longitudinal ligament should be added to the armamentarium of aortic injury treatment.


Assuntos
Traumatismos Abdominais/cirurgia , Acidentes de Trânsito , Aorta Abdominal/cirurgia , Aneurisma da Aorta Abdominal/cirurgia , Ligamentos Longitudinais/cirurgia , Traumatismo Múltiplo/cirurgia , Veia Safena/transplante , Lesões do Sistema Vascular/cirurgia , Ferimentos não Penetrantes/cirurgia , Traumatismos Abdominais/diagnóstico por imagem , Traumatismos Abdominais/etiologia , Dissecção Aórtica/diagnóstico , Dissecção Aórtica/etiologia , Dissecção Aórtica/cirurgia , Aorta Abdominal/diagnóstico por imagem , Aorta Abdominal/lesões , Aneurisma da Aorta Abdominal/diagnóstico , Aneurisma da Aorta Abdominal/etiologia , Aortografia/métodos , Angiografia por Tomografia Computadorizada , Humanos , Artéria Ilíaca/cirurgia , Masculino , Pessoa de Meia-Idade , Traumatismo Múltiplo/diagnóstico por imagem , Traumatismo Múltiplo/etiologia , Resultado do Tratamento , Lesões do Sistema Vascular/diagnóstico por imagem , Lesões do Sistema Vascular/etiologia , Ferimentos não Penetrantes/diagnóstico por imagem , Ferimentos não Penetrantes/etiologia
16.
Acta Clin Croat ; 56(3): 391-398, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29479904

RESUMO

Microdiscectomy (MD) is accepted nowadays as the operative method of choice for lumbar disc herniation, but it is not rare for neurosurgeons to opt for standard discectomy (SD), which does not entail the use of operating microscope. In our study, differences in disc herniation recurrence and clinical outcome of surgical treatment of lumbar disc herniation with and without the use of operating microscope were assessed. Our study included 167 patients undergoing lumbar disc surgery during a three-year period (SD, n=111 and MD, n=56). Clinical outcome assessments were recorded by patients via questionnaire forms filled out by patients at three time points. Operation duration, length of hospital stay and revision surgeries were also recorded. According to study results, after one-year follow up there was no statistically significant difference between the SD and MD groups in functional outcome. However, we recorded a statistically significant difference in leg pain reduction in favor of the MD group. According to the frequency of reoperations with the mean follow up period of 33.4 months, there was a statistically significant difference in favor of the MD group (SD 6.3% vs. MD 3.2%). There appears to be no particular advantage of either technique in terms of functional outcome since both result in good overall outcome. However, we choose MD over SD because it includes significantly lower recurrent disc herniation rate and higher reduction of leg pain.


Assuntos
Discotomia , Deslocamento do Disco Intervertebral , Microdissecção , Reoperação , Adulto , Idoso , Pesquisa Comparativa da Efetividade , Discotomia/efeitos adversos , Discotomia/métodos , Discotomia/estatística & dados numéricos , Feminino , Humanos , Deslocamento do Disco Intervertebral/diagnóstico , Deslocamento do Disco Intervertebral/cirurgia , Tempo de Internação , Vértebras Lombares/fisiopatologia , Masculino , Microdissecção/efeitos adversos , Microdissecção/métodos , Microdissecção/estatística & dados numéricos , Pessoa de Meia-Idade , Medição da Dor , Recidiva , Reoperação/métodos , Reoperação/estatística & dados numéricos , Inquéritos e Questionários , Resultado do Tratamento
17.
Turk Neurosurg ; 26(3): 452-5, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27161476

RESUMO

We are reporting the case of a 53-year old woman presenting to our hospital with a hemorrhagic low-grade glioma (LGG). She was admitted to a nearby general hospital where she had presented with aphasia, right hemiplegia and change of mental status. Computer tomography (CT) images showed a left temporo-parietal hemorrhage with mass effect. She was transferred to our hospital neuro-intensive care unit where emergency craniotomy was performed. A tumor with hematoma was removed and further histopathology analysis revealed tumor progression. We reviewed the literature reporting cases of central nervous system tumors hemorrhage and found that these types of events are exquisitely rare in adults with LGG. However these events are possible, suggesting that it should be included in the differential diagnosis of any patient presenting with intracranial hemorrhage. This case raises questions regarding the benefit of early versus late intervention for patients known to have LGG.


Assuntos
Neoplasias Encefálicas/cirurgia , Hemorragia Cerebral/cirurgia , Glioma/cirurgia , Afasia/etiologia , Neoplasias Encefálicas/complicações , Neoplasias Encefálicas/psicologia , Hemorragia Cerebral/etiologia , Hemorragia Cerebral/psicologia , Quimiorradioterapia , Terapia Combinada , Craniotomia , Feminino , Glioma/complicações , Glioma/psicologia , Hemiplegia/etiologia , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Procedimentos Neurocirúrgicos , Convulsões/tratamento farmacológico , Convulsões/etiologia , Tomografia Computadorizada por Raios X
18.
Opt Express ; 23(6): 7946-56, 2015 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-25837132

RESUMO

Photonic technologies will be at the heart of future terrestrial planet hunting interferometers. In particular the mid-infrared spectral region between 3.5 - 4.2 µm is the ideal window for hunting for young extra-solar planets, since the planet is still hot from its formation and thus offers a favorable contrast with respect to the parent star compared to other spectral regions. This paper demonstrates two basic photonic building blocks of such an instrument, namely single-mode waveguides with propagation losses as low as 0.29±0.03 dB/cm at a wavelength of 4 µm as well as directional couplers with a constant splitting ratio across a broad wavelength band of 500 nm. The devices are based on depressed cladding waveguides inscribed into ZBLAN glass using the femtosecond laser direct-write technique. This demonstration is the first stepping stone towards the realization of a high transmission mid-infrared nulling interferometer.

19.
Opt Express ; 22(15): 18335-53, 2014 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-25089453

RESUMO

The detection and characterization of extra-solar planets is a major theme driving modern astronomy. Direct imaging of exoplanets allows access to a parameter space complementary to other detection methods, and potentially the characterization of exoplanetary atmospheres and surfaces. However achieving the required levels of performance with direct imaging from ground-based telescopes (subject to Earth's turbulent atmosphere) has been extremely challenging. Here we demonstrate a new generation of photonic pupil-remapping devices which build upon the Dragonfly instrument, a high contrast waveguide-based interferometer. This new generation overcomes problems caused by interference from unguided light and low throughput. Closure phase measurement scatter of only ∼ 0.2° has been achieved, with waveguide throughputs of > 70%. This translates to a maximum contrast-ratio sensitivity between star and planet at 1λ/D (1σ detection) of 5.3 × 10(-4) (with a conventional adaptive-optics system) or 1.8 × 10(-4) (with 'extreme-AO'), improving even further when random error is minimized by averaging over multiple exposures. This is an order of magnitude beyond conventional pupil-segmenting interferometry techniques (such as aperture masking), allowing a previously inaccessible part of the star to planet contrast-separation parameter space to be explored.

20.
Opt Express ; 21(22): 27197-208, 2013 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-24216943

RESUMO

There are numerous advantages to exploiting diffraction-limited instrumentation at astronomical observatories, which include smaller footprints, less mechanical and thermal instabilities and high levels of performance. To realize such instrumentation it is imperative to convert the atmospheric seeing-limited signal that is captured by the telescope into a diffraction-limited signal. This process can be achieved photonically by using a mode reformatting device known as a photonic lantern that performs a multimode to single-mode transition. With the aim of developing an optimized integrated photonic lantern, we undertook a systematic parameter scan of devices fabricated by the femtosecond laser direct-write technique. The devices were designed for operation around 1.55 µm. The devices showed (coupling and transition) losses of less than 5% for F/# ≥ 12 injection and the total device throughput (including substrate absorption) as high as 75-80%. Such devices show great promise for future use in astronomy.

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