This PDF file contains the front matter associated with SPIE Proceedings Volume 11815, including the Title Page, Copyright information, and Table of Contents.

A system for measuring the orientation and power of sphero-cylindrical lenses has been developed. The system attempts to minimize the need for specialized equipment and training and instead relies on the ubiquitous cell phone camera, a magnetic stripe card, and a target pattern. By capturing an image of the target through the lenses under test and analyzing the distortion in the resulting image, the orientation and powers on sphero-cylindrical lenses can be determined. In modern eye clinics, the measurement of sphero-cylindrical spectacle lenses is readily measured with a lensmeter. However, there are many examples where this measurement is not feasible. This may include remote or rural locations where access to eye care may not exist, or require impractical travel. Furthermore, the on-going global pandemic has often put restrictions on contact between the patient and the eye care provider. Telemedicine, which can connect patients to eye care providers, lacks physical access to the spectacles for measurement. The system developed in this effort overcomes this limitation by allowing remote measurement of the lenses with items found in most households. Such a system would be beneficial to often underserved populations and expand access to quality eye care.

Optoacoustic imaging, also termed photoacoustic imaging, is an emerging functional imaging method in the field of biomedical applications. It combines the light absorption characteristics of tissues with the advantages of ultrasonic detection, and has the advantages of strong contrast, high sensitivity, and deep imaging depth. Therefore, this article uses the finite element software COMSOL Multiphysics to study the relationship between ultrashort laser pulses and the generated photoacoustic signals. In COMSOL, a laser with a pulse width of 5 ps and a wavelength of 532 nm is used as the excitation light source. Use mathematics module, heat transmission module, etc. to simulate the process of photothermal conversion-thermal expansion-generation of ultrasound in the photoacoustic imaging of the tissue-absorber system. In this way, the photoacoustic signal and its image are obtained. This study provides a theoretical basis for the application of picosecond laser pulses in photoacoustic imaging.

Recently, holographic optics such as volume holographic optical elements (vHOEs) receive increasing attention as optical combiners in augmented reality (AR) applications. Especially vHOEs fabricated by means of wave front printing have the potential to realize complex optical functions with high diffraction efficiency while maintaining excellent transmittance. We present the recording of a holographic combiner for AR applications fabricated by means of individually modulated recording wave fronts in our extended immersion-based holographic wave front printer setup. Holographic elements from our setup are made up of individual sub-holograms, so called Hogels. The implementation of two phase-only reflective spatial light modulators (SLMs) allows for the recording of Hogels and consequently vHOEs in a wide range of different configurations. Large-area vHOEs are achieved by adjacent recording of multiple Hogels in a step-wise fashion. Our immersion-based printer setup ensures a high numerical aperture for the recording configuration, which is directly linked to a wide angular range of possible replay configurations for wave front propagation in air. We present a reflective vHOE realizing a large off-axis to on-axis wave front transformation suitable as holographic combiner for retinal scanning displays. The vHOE is characterized by evaluating the diffractive properties of the hologram’s volume gratings, as well as investigating the vHOE’s combiner characteristics by means of field of view (FoV) and eye box size evaluation.

Clarity enhancement is a common treatment method to improve the appearance of gemstones. Classifying the level of enhancement is an important task to gemological laboratories since it is associate with gemstone’s value. Current visual observation based evaluation requires considerable time and experience to identify the filling materials consistently. It is also unable to record the distribution, nor to quantify the visual influence of fracture filling. To improve the quality of identification, we demonstrate a treatment detection technique based on multi-excitation fluorescence imaging. The system is designed to reveal the filling materials while mitigate the background fluorescence from the mineral. Proper excitation wavelengths were selected based on preliminary spectroscopy and imaging studies. The experimental prototype used multiple light emitting diodes as the light sources; and adapted color camera combined with filters to monitor the fluorescence image of treated gemstones. This research utilized emerald treatment detection for demonstration. The system can reveal popular fillers in emerald such as oil, resin, and mixture of chemical compounds, and demonstrates rapid detection of clarity enhancement in emeralds.

Light in nature is complex and dynamic, and varies along spectrum, space, direction, and time. While both spectrally resolved measurements and spatially resolved measurements are widely available, spectrally and spatially resolved measurements are technologically more challenging. Here, we present a portable imaging system using off-the-shelf components to capture the full spherical light environment in a spectrally and spatially resolved fashion. The method relies on imaging the 4π-steradian light field reflected from a mirrored chrome sphere using a commercial hyperspectral camera (400-1000 nm) from multiple directions and an image-processing pipeline for extraction of the mirror sphere, removal of saturated pixels, correction of specular reflectance of the sphere, promotion to a high dynamic range, correction of misalignment of images, correction of intensity compression, erasure of the imaging system, unwrapping of the spherical images, filling-in blank regions, and stitching images collected from different angles. We applied our method to Wytham Woods, an ancient semi-natural woodland near Oxford, UK. We acquired a total of 168 images in two sites with low and high abundance of ash, leading to differences in canopy, leading to a total 14 hyperspectral light probes. Our image-processing pipeline corrected small (<3°) field-based misalignment adequately. Our novel hyperspectral imaging method is adapted for field conditions and opens up novel opportunities for capturing the complex and dynamic nature of the light environment.

Lockheed Martin Space Systems Company Optical Payloads Center of Excellence is in process of standing up the Robotic Optical Assembly System (ROAS) capability at Lockheed Martin Coherent Technologies in Colorado. This currently implemented Robotic Optical Assembly has enabled Lockheed Martin to create world-leading, ultra-lowSWAP photonic devices using a closed-loop control robot to precisely position and align micro-optics with a potential fill factor of <25 optics per square inch. This paper will discuss the anticipated applications and optical capability when ROAS is fully operational, as well as challenge the audience to update their "rules of thumb" and best practices when designing low-SWAP optical-mechanical systems that take advantage of Lockheed Martin's ROAS capability. This paper will reveal demonstrated optical pointing and stability performance achievable with ROAS and why we believe these optical specifications are relevant for the majority of anticipated applications. After a high level overview of the ROAS current state, this paper will focus in on recent results of the "Reworkable Micro-Optics Mounting IRAD". Results from this IRAD will correlate to the anticipated optical specifications required for relevant applications.

The photonic band structure of plasmonic and nanophotonic materials and devices can be controlled by physical features much smaller than the optical diffraction limit. We present a methodology to correlate nanoscale structure to the photonic band structure directly using the cathodoluminescence (CL) signal generated by a sample in the scanning electron microscope. Further to conventional electron microscope imaging, we record the wavelength- and angular- distributions of luminescence in a highly-parallelized manner. The result is a wavelength- and angle- resolved data cube, which was transformed to observe the emission intensity in the energy-momentum basis revealing the photonic band structure.

Printing of optical waveguides is an approach to large-volume implementation of optical data transmission in conventional electronic systems. Flexographic printing can be used to apply optical waveguides with circular-segment cross-sections to planar substrates. In this work, a concept for integrating printed optical waveguides into printed circuit boards (PCBs) is investigated, taking the requirements of industrial processing into account. A planar waveguide structure model is defined that is applicable to lamination processes used in PCB manufacturing. Due to thermal stress on the substrate during this process, polymer waveguides are printed on polyimide (PI) substrate. To ensure optical functionality, matching refractive indices in the form of printed cladding structures are required. Manufacturing multilayer waveguide structures requires new processes for generating the end facets of the waveguide core. To reduce the attenuation caused by optical coupling, one primary requirement is low facet roughness. In this paper, we present a way to flexographic print fully cladded waveguides on PI substrates. Different waveguide layer compositions are characterized with respect to their geometry by confocal measurements. Milling with monocrystalline diamond cutters is presented as a method for preparing the end facets. Finally, the attenuation of the prepared waveguides is measured and discussed as a function of the waveguide and end facet properties. By this, flexographic printed and ready-to-integrate waveguides are achieved, approaching the target of optical PCBs.

While glass is an ideal material for optics, only a few microprocessing technologies are available. These technologies are usually limited regarding precision and freedom of design. A novel glass micromachining process is Laser Induced Deep Etching (LIDE). Without generating micro-cracks, introducing stress or other damages, it offers the possibility to precisely machine many types of glass. A broad range of features such as high-aspect ratio through holes, cutouts and slits in glass are available. In this work, LIDE is used to produce glass carrier substrates for integrated optical systems. Due to transmission characteristics and refractive index, the glass can be used as optical cladding for integrated polymer optical waveguides (refractive indices < 1.45). Cavities in glass, which can have different cross-sections e.g. u- or v-shaped, are filled with photoactive material by a doctor blade and function as an optical waveguide core. An additional approach examined in this work is the integration of optical fiber into v-shaped cavities. The system uses bare die laser diodes as transmitters and photo diodes as receivers bonded in front of the waveguide. LIDE technology allows to passively align the manufactured optical waveguide in front of the light source and detector due to mechanical features in the carrier substrate itself, eliminating the need for time-consuming and complex active alignment processes. This paper shows geometrical characteristics of waveguides and cavities, with a particular focus on surface roughness and subsequent filling ratio of the optical waveguide. Furthermore, the relative intensity distribution in the waveguide is presented and analyzed.

In order to suppress the polishing defects of single crystal silicon optical elements, the material removal mechanism and defect suppression technology in the polishing process of single crystal silicon were carried out. Based on the nanoindentation test, the mechanical properties of single crystal silicon were analyzed. Based on the X-ray photoelectron spectroscopy (XPS) test, the chemical element on the processed surface was studied, and then the chemical-mechanical coordinated removal mechanism in the polishing of single crystal silicon was analyzed. Then, this paper carried out the research on the bonnet polishing process of single crystal silicon optical elements. According to the experimental results, the influence of slurry characteristics on the removal efficiency and defects had been obtained, and an efficient processing method by bonnet polishing for obtaining high quality single crystal silicon elements was mastered.

As a new non-destructive imaging technology in the field of biomedicine, photoacoustic imaging technology combines the advantages of pure optical and pure acoustic imaging with good spatial resolution, high sensitivity, and strong penetrating power. In the photoacoustic microscopy imaging system, the acousto-optic coupling prism is a component for optical transmission and ultrasonic detection. It is usually composed of an irregular prism and a spherical concave acoustic lens at the bottom. Because the spherical acoustic lens has a poor focusing effect on the ultrasonic beam, the accuracy of ultrasonic detection is low. In order to solve this problem, we propose an optimization method to eliminate the influence of acoustic lens on the beam transmission. A collimating lens is added to the acousto-optic coupling prism with an aspheric acoustic lens at the bottom of the system. In this paper, Zemax optimizes the curvature coefficient and thickness of the collimating lens to eliminate the deteriorating effect of the aspheric acoustic lens on the beam transmission, and evaluates the optimization effect by analyzing the spot and MTF image. The simulation results show that the collimating lens can eliminate the influence of the aspheric acoustic lens on the beam transmission, so that the optical focus and the acoustic focus can be kept coaxial and confocal, and the detection efficiency of the photoacoustic signal can be improved. This work has theoretical guiding significance for the study of photoacoustic microscopy imaging with large depth of field.

Through the immense scientific efforts of the past two decades, light field visualization is now emerging in the industry, and commercial, everyday use cases are also expected to benefit from this glasses-free true 3D technology in the near future. While the technology itself may enable a natural 3D experience, there are, in fact, certain situations where visualization quality is not optimal. This can be due to the attributes of light field capture, transmission, compression, and numerous other factors that may degrade the perceived quality. However, the impact of such degraded quality fundamentally depends on the actual use case at hand. For example, while a specific amount of generic blur or disruption in the smoothness of the continuous horizontal and/or vertical parallax may cause minor inconveniences in a given use case, it may result in significant errors and substantial issues in another. In this paper, we analyze the use-case-specific quality degradations of light field visualization. Each and every key performance indicator of light field visualization quality is addressed, and their effects are separately studied in the context of each use case. Display and content parameters, such as angular resolution, are examined on the level of individual and combined thresholds. The investigated use cases cover industrial, medical, commercial, educational, cultural and communicational scenarios. Therefore, both active and passive utilizations are considered, and a special emphasis on task performance is included in this paper.

Time-resolved single-photon detection is a robust technique exploited in many fields, ranging from biology, e.g. in fluorescence lifetime imaging (FLIM), to industrial fields, such as in Light Detection and Ranging (LiDAR). Such technique can take major advantage from Single-Photon Avalanche Diodes (SPADs) and their single-photon sensitivity and picosecond time-resolution. For best system design, environmental conditions and optics should be simulated along with SPAD’s actual parameters. Monte Carlo simulations are usually employed, being able to emulate detector’s non idealities and photons’ statistical behavior. However, those simulations are time-consuming. As an effective alternative, we present a detailed discrete-time statistical model for SPAD detectors. The proposed analytical model provides the expected photon time-distribution, given the actual incoming photon-rate, optical setup, laser power and pulse width, background light, object properties, and takes into account all SPAD’s nonidealities, such as hold-off time, crosstalk, afterpulsing, photon detection efficiency, and dark-counting rate. Moreover, the model can predict and correct one big limitation of SPAD systems, namely the detector dead-time (every time a photon is revealed, the SPAD needs to stay quenched for a not nil time interval), which causes distortion in the measured timing histogram, known as “pile-up”. To this purpose, we present how our reversed model can be applied to the measured histogram in order to compensate and correct such a distortion, so to estimate the actual incoming photon distribution. Eventually, the model can be used for both single photon Time-Correlated Single Photon Counting (TCSPC) and multi-photon detection (free-running) regimes, whether the timing electronics has a dead-time shorter than the detector’s one, resulting in a powerful design tool.

Compressive sensing has been used to demonstrate scene reconstruction and source localization in a wide variety of devices. To date, optical compressive sensors have not been able to achieve significant volume reduction relative to conventional optics of equivalent angular resolution. Here, we adapt silicon-photonic optical phased array technology to demonstrate, to our knowledge, the first application of compressive imaging in a photonicintegrated device. Our novel sensor consists of an 8 × 8 grid of grating couplers with a spacing of 100 μm. Path-matched waveguides route to a single multimode interferometer (MMI), which mixes and randomizes the signals into 64 outputs to be used for compressed sensing. Our device is fully passive, having no need for phase shifters, as measurement matrix calibration makes the measurements robust to phase errors. For testing, we use an Amplified Spontaneous Emission (ASE) source with a bandwidth of 40 nm, centered at 1545 nm. We demonstrate simultaneous multi-point (2 sources demonstrated in this work) brightness recovery and localization with better than 10 arcsecond precision in a sub-millimeter thick form-factor. We achieve a single source recovery rate higher than 99.9% using 10 of the 64 outputs, and a 90% recovery rate with only 6 outputs, 10 times fewer than the 64 needed for conventional imaging. This planar optical phased array compressive sensor is well-suited for imaging sparse scenes in applications constrained by form factor, volume, or high-cost detectors, with the potential to revolutionize endoscopy, beam locators, and LIDAR.

In this paper, work to intensify the security of a forward compatible integrated asynchronous GPON/XGPON is presented by incorporating pseudo user scheme (PUS). Both the PON standards can work on same optical distribution network and security is beefed up from optical line terminal and optical network units without any tampering with the transmission line. Comparison of GPON/XGPON system has been done with and without PUS scheme and probability of correct bit detection is analyzed, both for authenticate receiver and eavesdropper. The performance of spectral amplitude codes such as Diagonal Double Weight (DDW) codes, Multi-Diagonal (MD) codes is studied as pseudo user. Further, their reliability to hide the authentic information under virtual user is observed. It is evident that system with PUS provides high security and out of DDW, MD codes, cross-correlation based DDW codes are less correctly detectable at eavesdropper receiver.

Raman optical cooling has been observed in structured fiber optics designed to enhance the Raman anti-Stokes emission through resonance. However, these approaches are not amenable to large area cooling under a portion of the solar spectrum. This work explores the use of planar structures to increase cooling efficiency, increase device area, broaden the working wavelength band, and reduce cost. Simple, planar structure require optical thin Raman shift layers. Since, so that a simple quarter-wave or series of quarter-wave reflector can be engineered to suppress the heat releasing Stoke’s shifted light. In-turn the main material challenges associated with ~ 10 nm crystalline films is the requirement for at least one dimension of the film to support domains (grain sizes) large enough to support the phonons needed for Raman scattering. As expected ten nanometer diamond particles do not appear to support the bulk-crystal phonon modes responsible for the 1332 cm-1 Raman shift suggesting new material approaches. A new scalable approach is presented and in parallel new applications such as water vapor recovery by cooling explored.

With the rapid development of information in the new era, a concept is put forward. You can observe a scene that doesn't exist near you at home, outdoors and anywhere. It can be a swimming pool, a museum or even an Olympic Games. In this paper, we design a 3D scene roaming system based on augmented reality, which uses augmented reality technology to build a 3D virtual world presented by AR devices in the real world, and with the support of AR devices, users can walk around freely and autonomously in the 3D virtual world to observe the presented scene in an all-round way. The design of the roaming system is mainly developed in Windows environment. The unity3d platform is used for 3D scene design and creation. Mask technology is used to realize the Mask on the basis of 3D scene. A transparent invisible film is pasted on the surface of 3D scene to hide some scenes. It is required that the hidden scenes can be seen only after the scene roaming through the Mask film. Using the ARcore development technology of building the software platform of augmented reality application launched by Google to realize the presentation of 3D scene and human-computer interaction. Package all programs into SDKs and send them to Android platform for running and effect verification.

Photoacoustic imaging (PAI) has gradually developed into a new and important imaging technology, which combines the high contrast of optical imaging and the high resolution of ultrasonic imaging to achieve a deeper imaging of biological tissue, and has been widely used in biological imaging. The basic principle of photoacoustic imaging is that a short pulse of laser is used to illuminate biological tissue. As photons pass through biological tissue, some of them are absorbed by biological molecules such as hemoglobin, DNA-RNA, fat, water, melanin and cytochrome. In PAI, the light absorption mechanisms generally include electron absorption, vibration absorption, stimulated Raman absorption and surface plasmon resonance absorption. The absorbed light energy is usually completely converted to heat energy by the non-radiative relaxation of the excited molecules, and the pressure wave caused by the heat energy is transmitted in the tissue to form ultrasonic wave, namely the photoacoustic signal. The photoacoustic signal reconstruction generated by the detection of ultrasonic transducer can be obtained from biological tissue. The absorption of blood in visible band is much higher than that of other tissues (except melanin) to achieve high resolution imaging of blood vessels without exogenous markers. Due to the characteristics of biological tissue, it has different degrees of absorption to different wavelengths of light, resulting in different heat and pressure waves generated, the final received ultrasonic wave is different, which will affect the final image results. Based on the finite element analysis method, this paper establishes four complete coupling modules in COMSOL software: coefficient form partial differential equation module, biological heat transfer module, solid mechanics module and transient pressure acoustic module. By setting different optical parameters to explore the degree of absorption of different light waves by biological tissues, so as to find the best wavelength of light for the experiment.

As a kind of carcinoma with extremely high mortality and morbidity, there are immense demand for early detection and diagnosis of gastric carcinoma. At present, in medical research, the initial detection of gastric tumors mainly uses the laser detection methods. The Monte Carlo method has good adaptability for exploring the process of photon transportation, therefore, it has the value of extension and application in the research of photons’ transportation in biological tissues. Through exploring the influence of the tumor in gastric tissue on the photon transmission, it can help determine the existence of gastric tumor. After established the corresponding model, we using the program to perform the fitting process, analysising the result then we can draw a conclusion that: according to the trajectory analysis of photons, gastric tumors absorb more photons than the gastric tissues, and such basic features can be used to determine the existence of gastric tumors. Through the analysis of optical absorption density and fluence rate: when photons initially enter the first gastric tissue layer(the Z-axis 0-0.2cm region), because the water layer’s weak optical absorption and scattering effects, optical absorption decreases slowly: from 0.0805cm^-1 drop to 0.073cm^-1. After entering the second layer, the layer of gastric tissue, because the absorption and scattering effect of gastric tissue is higher than water, the optical absorption density rises sharply to 8.7028cm^-1, then with the photon weight decreasing, the optical absorption density continues to drop to 0.7128cm^-1. After entering the third layer, the layer of gastric tumor, the optical absorption density rises again. When z=0.5cm, the optical absorption density approaches to 1.8848cm-1 and then slowly drops to 0.1338cm^-1. Finally, photons enter the second layer of gastric tissue and water layers, and continue to decrease to approach 0cm^-1. These data demonstrate that there are effects of gastric tumor on photon transport in gastric tissues. This research will also provide reference and theoretical guidance for the optical imaging and diagnosis of gastric tumors.

As a new non-destructive medical imaging technology, photoacoustic imaging combines the advantages of optical imaging and ultrasonic imaging, which has the characteristics of high contrast and strong penetration ability. It can effectively image biological tissues and functions, and be applied to the early diagnosis and treatment of tumors, cardiovascular and cerebrovascular diseases, which has broad prospects for development in the field of biomedicine. When photoacoustic imaging is used to collect a large number of pathological medical images, it is prone to slow data transmission and poor reconstruction effect. In an effort to speed up data transmission and improve image reconstruction quality, this article is based on photoacoustic imaging technology and compressed sensing reconstruction algorithm, a virtual simulation platform of photoacoustic tomography combined with compressive sensing is built by using K-wave simulation toolbox to simulate the propagation process of photoacoustic signals, and the hard thresholding pursuit algorithm is used to complete the signal reconstruction. In order to verify the performance of the virtual simulation platform, in this paper, the local vascular network map is compressed and reconstructed. The obtained image retains the main information in the original image, and the edge features are similar. The results show that the virtual simulation platform can reconstruct high quality images by a small amount of data, which provides important significance and theoretical research value for compressed sensing reconstruction algorithm applied in photoacoustic imaging.

Camouflage patterns consist of complex patterning where the reflectance, as a function of wavelength of each pattern segment is specified. The complexity of camouflage patterns establishes a need to determine camouflage pattern reflectance characteristics as a function of distance to an observer. Different camouflage pattern segments incoherently combine at far field to become a segment-weighted, space-averaged, reflectance spectrum, i.e., the apparent reflectance spectrum of the camouflage pattern. This report demonstrates application of an algorithm for camouflage pattern segmentation, which is for parametric modeling of apparent reflectance spectra.

Existing and future possibilities of using fibre-optical technologies to develop electronically controllable components are considered. The need for such fibre-optical components comes from the desire to bring more control over ultrashortpulsed all-fibre laser parameters and to create on their basis next-generation radiation sources. The report analyses the effects that could be used (some are already used) for controlling the electro-magnetic field inside the optical fibre. A conclusion is then reached that a directed development of fibre-optical technologies is needed, including hybrid technologies on their basis.

We present a teaching concept which combines theory, experimental work, project management and organization. As part of the Earth and Space Physics and Engineering education at DTU Space, a group of first year undergraduate students were given the task to design, build and test a DC magnetron sputtering system within a very limited budget and time frame. The teaching concept is designed to promote the students’ autonomous learning, and a major part of the project was to teach the students how to develop group dynamics successfully. The students successfully managed to build a direct current magnetron sputtering system wherein a plasma glow was produced. The system can be used for depositing thin film coatings, an enabling technology for numerous applications.

We present the concept of a new method for amplification of laser pulses. It is based on structured noise-like pulses (also known as double-scale pulses or chaotic bunches) capable of carrying relatively high energy and supporting high average radiation power. The possibility of efficient conversion of the energy carried by these incoherent pulses into coherent ones enables development of an alternative method for laser pulse amplification. The report discusses limitations and prospects of the proposed method.

In this work, an experimental analysis of the Schlieren technique is presented to get the temperature distribution that is generated around the optical fiber. Laser light (λ = 450 nm) travels through this fiber (multimode optical fiber, 105/125 μm) and on its tip contains silver nanoparticles. The thermal gradient arises from the absorption of laser radiation by the silver nanoparticles adhered on the fiber tip. Schlieren Z-type setup was used, which has of a light source, two parabolic mirrors, a knife, and the camera. The analysis of the temperature distribution was carried out by obtaining Schlieren images in air through the digital camera. As a temperature calibration factor, the boiling temperature of ethanol (78 °C) was used, that is, previously, the tip of the optical fiber was immersed in ethanol and the laser power was set to the value before the appearance of the boiling bubbles. Subsequently, the optical fiber was placed in the Schlieren arrangement, and taking the above we find that the tip of the optical fiber reaches ~ 80 °C when it is in the air, this value is approximate to the boiling temperature of ethanol, the possible cause of the temperature variation is given by the transfer of heat in and out of the ethanol.

A simple and inexpensive method of measuring heart beats was established using Fabry-Perot interferometry (FPI). The sensor consists of a bracelet, the Fabry-Perot cavity is formed with a thin aluminum foil and the tip of a singlemode fiber optic. The fiber and aluminum foil are inserted into bracelet by means of easily assembled mechanical components. Fiber-coupled laser diode (1550 nm wavelength) was used to provide the optical signal through a 50:50 fiber coupler. Furthermore, we used a photodetector to transform this signal into an electrical one and an oscilloscope to analyze this signal. The sensor measures heart rate in the time domain, detecting interference fringes through the sensor and displayed on an oscilloscope. The interference phenomenon takes place in the Fabry-Perot cavity (CFP) which is formed by the thin aluminum plate and the tip of the optical fiber. By analyzing the signal from the oscilloscope, it is possible to measure the heart rate. The analysis presented in this work shows several advantages over traditional electrocardiograms, real-time measurement and simplification in the experimental setup, coupled with its high sensitivity for the analysis of cardiograms.

This work reviews the search for extraterrestrial life signatures with a special focus on the fluorescence microscope that we have been developing for the life-signature search on Mars and other sites. The surface and subterranean Mars, clouds of Venus, the Moon, asteroids, icy bodies, such as the moons of Jupiter and Saturn, and so on are important sites for life-signature exploration in the solar system. One possible exploration strategy is to target characteristics similar to those in terrestrial life, such as microorganisms with metabolic activity and similar uniform small structures microbes surrounded by a membrane that primarily comprise carbon-based molecules. These characteristics can be analyzed with fluorescence microscopy, which has a high spatial resolution and employs a combination of fluorescent pigments to distinguish microbial properties. Following an introduction, the life signature search and astrobiological analysis of the targeted characteristics are discussed. The extraterrestrial life exploration methods using a microscope are described. Also, other methods, including mass spectrometry, the sterilization-and-comparison method (detection of ability to die), proliferation, and analysis of shape, color, growth, or movement, are discussed. Lastly, we overview the life-signature detection fluorescence microscope that we have been developing, and present the Bread Board Model of it.

With latest significant improvements and changes in optical sensors characteristics it is inevitable that optical system requirements are getting tougher every day. In this work we would like to show benefits of taking a side step from rotational symmetry in optical systems design, introducing freeform optical elements, that can be a good instrument to push optical specifications to required level, especially with latest achievements in optical elements manufacturing and assembly. Main optical characteristics that can be addressed by applying freeform are optical / SMIA TV distortion and field curvature / astigmatism with most promising results in small total track wide angle and telephoto applications. In this work we would like to show main steps of design process as well as comparison with conventional rotationally symmetric optical systems.

The aim of the work was to compare measurements of eccentric fixation in children with amblyopia using two different methods, a traditional visuoscopy and MIT. Monocular fixation was evaluated using visuoscopy and MIT in 16 patients (from 5 to 9 years old). Measurements were started with the better seeing eye to compare the results obtained with the amblyopic eye. All study participants were selected with anisometropic and refractive amblyopia. Visuoscopy is simpler than MIT and less dependent on patient responses, so visioscopy can be used for young children who have not yet acquired verbal skills. Children over the age of 5 can more easily understand the MIT method and get more reliable results. By determining the visual acuity and fixation point, it is possible to determine the maximum visual acuity achievable with an appropriate fixation. The MIT and visuoscopy methods complement each other, both of which can be used to identify the fixation point. In Latvia, amblyopia treatment is carefully performed in various vision institutions, but assessment of eccentric fixation is very rare. Evaluation of eccentric fixation can help predict the outcome and treatment progression of amblyopia.

The report is devoted to the development of an optical scheme and design features for a sculptural group, which is supposed to be installed on a city street. The idea of the composition is that an optical system will be inserted into the sculpture, which will collect sunlight on the image receiver. In this case, the receiver will be wooden. During daylight, the optical elements should leave a track on the receiver. The operating conditions limit the desired disposition of the scheme elements. The manufacturing conditions and the quality of parts restrict the position of the receiver and structural parts. Thus the article will present the options for the optical scheme obtained for the implementation of the sculptural composition, also show optical solutions, which proposed for realization. The project is a part of the graduation project of the Stieglitz Academy's student, and the team from ITMO University helps with the design and calculation of the optical scheme.