Monochromatic Light Source Research Articles

Design and characterization of a novel turbidity sensor based on quadrature demodulation

Abstract Turbidity is regarded as a comprehensive indicator in water quality monitoring, and the turbidity sensor deployed in the water supply network can record the dynamic changes of water quality in time. However, the weak photoelectric signal from the photodetector contains a quantity of noise. In order to improve signal-to-noise ratio (SNR), a novel on-line turbidity sensor based on quadrature demodulation principle has been proposed in this paper. A near-infrared light-emitting diode (LED) with a wavelength of 860 nm was selected as a stable monochromatic light source, and a photodiode (PD) with an angle of 90° to the incident light from the LED was selected as the photodetector. Using signal modulation and demodulation technology, the weak photoelectric signal extraction, conversion, amplification and output of the turbidity sensor were realized through the effective integration. A corresponding test apparatus of the turbidity sensor was established and experimental results showed that within a 0~5 NTU measurement range, the turbidity sensor had good linearity and stability, the relative measurement error was within ±1% and the limit of detection could reach as low as 0.0049 NTU. The developed turbidity sensor has good detection performance and can meet the needs of low turbidity detection of drinking water.

Simulation and analysis of fresnel diffraction with arbitrary shaped apertures

Abstract When studying diffraction and related issues, one often encounters the need to anticipate and estimate the diffraction patterns of variously shaped apertures. Optical experiments demand high environmental standards, and creating diffraction screens is cumbersome. Designing specialized optical experiments for such simple purposes is time-consuming and labor-intensive, and the clarity of the diffraction patterns is hard to guarantee. Therefore, obtaining diffraction patterns quickly and accurately in different situations has become a bottleneck. This article first obtains the integral expression of the Fresnel diffraction light field produced by a monochromatic point light source illuminating a diffraction hole based on Kirchhoff’s diffraction theory. Then, it establishes a mathematical model of the hole to obtain the integral element and uses mathematical software for computational simulation, obtaining diffraction patterns applicable to any shape hole. The paper performs calculations taking uppercase English letters as shaped aperture examples and conducts detailed analysis of their diffraction patterns.

A Photoenzymatic Pathway for Gram-Scale Synthesis of 25-Hydroxyvitamin D3.

Vitamin D and its analogues play a crucial role in promoting the well-being of both humans and animals. However, the current synthesis of this vital class of nutrients heavily relies on chemical transformations, which suffer from low step- and atom-efficiency due to lengthy synthetic pathways. To enhance sustainability in the chemical industry, it is necessary to develop alternative synthetic processes. Herein, we present a photoenzymatic approach for synthesizing 25-hydroxyvitamin D3 from 7-dehydrocholesterol. In this sequential synthesis, 7-dehydrocholesterol is initially hydroxylated at the C25 C-H bond, resulting in an 85 % conversion to 25-hydroxyl-7-dehydrocholesterol. Subsequently, by employing photo-irradiation using a monochromatic LED ultraviolet light source in a batch reactor and thermal isomerization, 25-hydroxyvitamin D3 is obtained in satisfactory yield. This photoenzymatic process significantly reduces the need for purification steps and allows for gram-scale synthesis of the target product. Our work offers a selective, efficient, and environmentally friendly method for synthesizing 25-OH-vitamin D3, addressing the limitations of current synthetic approaches.

A Study on the Irradiance Scintillation Characteristics of Monochromatic LED-Based Visible Light Communication Systems in Weak-to-Strong Turbulence

Atmospheric turbulence causes transmitted light to fade randomly, which results in irradiance scintillation fluctuations in the received signal and significantly affects the quality of wireless optical communication systems. In this paper, we investigate the propagation characteristics of a monochromatic light-emitting diode (LED) light beam through weak-to-strong turbulence. Considering the spatial incoherence of a monochromatic LED light source, the emitted light field of a monochromatic LED light source is represented by a random field multiplied by a deterministic field that follows a Gaussian distribution. Then, based on the extended-Rytov theory, a closed expression for the irradiance scintillation index under weak-to-strong turbulence is derived. In addition, the expression for the fading probability governed by the Gamma–Gamma model is given. Finally, the effects of near-earth atmospheric refractive index structural parameters, signal propagation distances, and working light wavelengths on propagation characteristics of the LED-based VLC system are simulated and compared with those of the laser-based one. The results theoretically confirm that laser light sources are more susceptible to atmospheric turbulence along the propagation path than monochromatic LED light sources. The investigation in this paper can provide theoretical support for the design of visible light communication systems in practical applications.

Optimization of vibration and sound insulation in GPLRC honeycomb structures based on circle chaos mapping and Levy flight-enhanced YDSE with constraints

Utilizing the first-order shear deformation theory (FSDT) and Hamilton's principle, dynamic equations for tunable Poisson's ratio metamaterial honeycomb sandwich panels have been derived. These panels include petal-shaped, star-shaped, and butterfly-shaped designs. The acoustic response of these panels when subjected to plane harmonic sound waves has been formulated, treating them as fluid-structure interaction systems. To enhance the structural vibration and sound propagation attributes, traditional metallic aluminum has been replaced with graphene platelet-reinforced composites (GPLRC). Through computational analysis and finite element simulation data, the natural frequencies and sound transmission loss (STL) characteristics of the panels have been determined. An improved heuristic algorithm called the circle chaos mapping and levy flight enhanced Young's double-slit experiment optimizer (CLYDSE) has been introduced to optimize their vibrational and acoustic properties. This algorithm builds upon Young's double-slit experiment optimizer (YDSE) by incorporating circle chaos mapping for initializing a monochromatic light source and utilizing the levy flight principle for more accurate search results. These enhancements allow the CLYDSE algorithm to avoid local optima and improve convergence velocity. A penalty function method was employed to establish mass and equivalent elastic modulus as optimization constraints, aiming to achieve superior specific stiffness. Finally, structural optimization using the proposed CLYDSE method was conducted to enhance the vibrational and acoustic performance of the three types of honeycomb sandwich panels. The results validate the effectiveness of the theoretical model in predicting vibration and acoustic response, as well as the improved performance of the CLYDSE algorithm in terms of convergence velocity and optimization accuracy. This demonstrates the algorithm's efficacy in refining the acoustic and vibrational qualities of these advanced honeycomb structures.

Influence of spectral bandwidth on the working curve in vat photopolymerization

In vat photopolymerization, 3-dimensional parts are fabricated by using patterned light to spatially cure a liquid resin. One of the foundational measurements for vat photopolymerization is known as the working curve whereby the depth (i.e. thickness) of cured resin is measured as a function of radiant exposure. The commonly applied mathematical model for the working curve – known widely as the Jacobs model – assumes a monochromatic light source. The Jacobs model has been widely used, but in many cases significant deviations between the Jacobs model and the data have been observed. Herein, we extend the Jacobs model by deriving a polychromatic model that accounts for broadband light sources (e.g. light emitting diodes, LEDs). We demonstrate through experiment and theory that in certain cases the deviations from Jacobs’ original model can be explained and understood as an optical ‘inner filter’ effect. The ability of the Jacobs model to capture the working curve behavior is shown to be dependent on the bandwidth of the light source in conjunction with the gradient in the absorption spectrum of the resin in the vicinity of the light source spectrum. Additionally, we offer an empirical model function that better fits experimental data and allows for an improved estimate of model parameters. Broadly, this work aims to strengthen the conceptual link between the working curve measurement and the photophysical parameters that are intrinsic to vat photopolymerization printing.

Chemical bath deposited CdTe thin film: Optical, electrical, and photoresponse aspects

Owning a narrow bandgap, remarkable optical and electrical properties with notable stability has made cadmium telluride (CdTe) an immensely vital semiconductor to develop cutting-edge optoelectronics. Taking these properties in to account, CdTe thin film is deposited employing the chemical bath deposition (CBD) technique. The X-ray diffraction analysis of the as-deposited thin film unveiled the composite crystalline structure, incorporating cubic, hexagonal, and tetragonal phases. The energy dispersive X-ray analysis and X-ray photoelectron spectroscopy ascertained the chemical composition of CdTe thin film. Distinctive Raman peaks are detected at 141 and 167 cm−1, signifying the presence of Cd-Te bond in the deposited thin film. The comprehensive evaluation of scanning electron micrographs emphasized the firm adhesion of the film to the substrate and displayed a uniform overlay of microstructures resembling rods. The observations from atomic force microscopy unveiled uniform grain structure with topographical features of hills and valleys. The UV-Visible spectroscopic examination elucidated that the as-deposited thin films exhibits a direct optical bandgap value of 1⋅59 eV. Temperature-dependent analysis of d.c. electrical resistivity exhibited a descending pattern, substantiating thin film's semiconducting attributes. The investigation into the photoresponse attributes of the thin film is accomplished by subjecting it to a polychromatic light, green and red monochromatic light source with an intensity of 50 mW/cm² employing three different biasing voltages. The thin film demonstrated maximum photocurrent for red light source than polychromatic and green light with maximum responsivity of 59⋅4 μA/W and detectivity of 17⋅7 × 106 Jones. These findings provide valuable insights on the photoresponse behavior of CBD deposited CdTe thin film in its as-deposited form.

Tuning the luminescence color of Eu3+- and alkali-ion-codoped Sr2CaWO6 orange-red phosphors: Eu3+ site distribution and site-selective photoluminescence studies

In this study, Eu3+- and alkali-ion (M+)-codoped Sr2CaWO6:x (Eu3+, M+) (x = 0.01–0.10) were synthesized via a solid-state reaction. The effects of different Sr/Ca ratios, types of monovalent metal ions (M+ = Na+, K+, and Li+), and doping concentrations were systematically investigated. The crystalline phase, photoluminescence (PL) properties, lattice site occupied by the Eu3+ ion, Eu3+ site distribution, and site-selective PL properties were evaluated by x-ray diffraction, PL/photoluminescence excitation (PLE) spectroscopy with a monochromatic light source, PL quantum efficiency (QE) measurements, and high-resolution PL/PLE spectroscopy with a wavelength-tunable laser. A dependence of the PL asymmetry ratio for the 5D0–7F1,2 transitions on the Sr/Ca ratio was identified and quantified for the first time. Based on the site-selective PL measurements, this behavior was ascribed to the enhancement of Eu3+ local distortion by Sr2+ substitution at the A site at lower Sr/Ca ratios (<2) and to the high symmetry of the ligand structure of EuO6 octahedra owing to Ca2+ substitution at the B site at higher Sr/Ca ratios (>2). The PLE results provided insight into the Eu3+ site distribution, which explained the orange-red PL and PL QEs of the synthesized phosphors.

INFLUENCE OF LOW-INTENSITY LIGHT ON THE BIOSYNTHETIC ACTIVITY OF THE MEDICINAL MACROMYCETE LARICIFOMES OFFICINALIS Laricifomes officinalis (Fomitopsidaceae, Polyporales) in vitro

Understanding the impact of artificial lighting on the biosynthetic and biological activity of medicinal mushrooms will help enhance technologies aimed at obtaining bioactive compounds. The aim of our work was to determine the influence of low-intensity quasi-monochromatic light on biosynthetic activity, including the antioxidant activity of the medicinal fungus Laricifomes officinalis under submerged cultivation conditions. Methods. The effect of light on the biosynthetic activity of L. officinalis was studied using sources of low-intensity coherent monochromatic laser light and quasi-monochromatic radiation of light-emitting diodes (LEDs) with specified spectral-intensity characteristics. Results. The most stimulating effect on the biosynthetic activity of the L. officinalis strain was observed when samples were irradiated with blue (488 nm laser and 470 nm LED) and red (650 nm LED) light. Under these conditions, there was an increase in the synthesis of mycelial mass, polysaccharides, and the quantity of total phenolic compounds. Low-intensity light irradiation caused changes in both the quantitative and qualitative composition of the fatty acid profile of the mycelial mass. Red light irradiation resulted in an increase in the quantity of polyunsaturated fatty acids. A correlation was established between the quantity of total phenolic compounds and antioxidant activity. Conclusions: The research results provide grounds to consider low-intensity visible light as a promising regulator of the biosynthetic activity of L. officinalis in the biotechnology of its cultivation.

Design and Control of a Laser Cooling System for Wavelength Stabilization of a Monochromatic Light Source

Design and Control of a Laser Cooling System for Wavelength Stabilization of a Monochromatic Light Source

One pot synthesizing of cobalt (III) and (IV) oxides/polypyrrole nanocomposite for light sensing in wide optical range

A highly porous potato-shaped nanocomposite, Co(111) and Co(IV) oxide/polypyrrole (Co2O3-Co3O4/Ppy), is synthesized employing a one-pot procedure involving the slow oxidation of pyrrole using Co(NO3)2. The exceptional physical characteristics of this nanocomposite are accompanied by impressive optical properties, marked by a bandgap of 1.72 eV. Its absorbance spans across the UV, visible (Vis), and infrared (IR) regions, making it a promising candidate for optoelectronic applications such as photodetectors designed for light sensing within this extensive optical range that encompasses a substantial portion of the electromagnetic spectrum. This Co2O3-Co3O4/Ppy thin film photodetector is subjected to electrical testing under varying light conditions, leading to the determination of the photocurrent density (Jph) value of 0.26 mA.cm−2. When evaluated under different monochromatic light sources ranging from 340 to 730 nm, distinct Jph values are observed for each wavelength, reflecting the nanocomposite’s ability to effectively interact with photons across this spectrum. The measured responsivity (R) and detectivity (D) values further underscore the photodetector’s efficiency. At 340 nm, the R and D values stand at 1.22 mA.W-1 and 0.275 × 109 Jones, respectively. Similarly, at 730 nm, these values are 1.21 mA.W−1 and 0.270 × 109 Jones. The combination of these favorable findings, including cost-effectiveness and high stability, position the Co2O3-Co3O4/Ppy nanocomposite as an optimal choice for a wide range of industrial applications, attesting to its potential impact in the field.

16-channel snapshot multispectral imaging based on integrated Fabry Perot microcavity array

<sec>By designing and fabricating a narrow-band Fabry-Perot multi-beam interference spectroscopic microcavity array, and integrating it with a visible light detector focal plane array, we demonstrate a small compact multispectral imaging detector. The micro-cavity filter array with 4×4 basic repeating units and a total of 2048×2048 pixels is obtained on a quartz substrate by the four-fractal combination lithograph-etching process. Then the micro miniatured multispectral imaging detector is formed by fitting with the detector chip. The depth and precision of the etching will determine the distribution and offset of the central wavelength of the narrowband spectral channel respectively. The results show that the etching rate of reactive ion is (3.6 ± 0.2) Å/s, and the process is stable and controllable. Due to the different etching depths, the basic repeating unit forms 16 different levels of steps, and the process achieves the design expectation well.</sec><sec>The results are obtained as follows: the response spectrum peak of the microcavity array sample varies from 520 to 680 nm, the free spectrum range is 160 nm, the full width at the half-peak is less than 10 nm, the transmittance is about 70%, the relative half-width of the transmittance peak at 590 nm is 1.19%, and the waveform coefficient is 2.78. A 16-channel multispectral camera is constructed by using the optical micro-precision assembly device to realize the precise alignment and the fitting of the micro-cavity filter array and the image sensor. Xenon lamp and monochromator are used as tunable wavelength monochromatic cooperative light source to detect the effect of 16-channel snapshot multispectral imaging on a pixel scale. The results show that the multispectral imaging detector has 16 different narrow-band response spectra. The characteristic spectrum of the target can be clearly distinguished by spectral channel.</sec><sec>When imaging the target with known spectral characteristics, for a certain frame of multi-spectral image, selecting a suitable spectral channel can eliminate the background in the field of view through image subtraction and improve the contrast of the target. In the dark room condition, we take the LED light source with center wavelength varying in a range between 528 and 589 nm as the target (the wavelength coincides with the working wavelength of the spectral channel), and effectively suppress the background through the spectral differential intensity subtraction, which can improve the accuracy and sensitivity of the target capture. The 16-channel snapshot multi-spectral imaging detector based on integrated Fabry-Perot microcavity array has the advantages of small size, high integration and strong environmental adaptability, and is expected to play a role in realizing the real-time detection of weak moving targets, auxiliary diagnosis of skin surface observation, and high dynamic range imaging of target observation under backlight conditions.</sec>

Indoor Self-Powered Perovskite Optoelectronics with Ultraflexible Monochromatic Light Source.

Self-powered skin optoelectronics fabricated on ultrathin polymer films is emerging as one of the most promising components for the next-generation Internet of Things (IoT) technology. However, a longstanding challenge is the device underperformance owing to the low process temperature of polymer substrates. In addition, broadband electroluminescence (EL) based on organic or polymer semiconductors inevitably suffers from periodic spectral distortion due to Fabry-Pérot (FP) interference upon substrate bending, preventing advanced applications. Here, ultraflexible skin optoelectronics integrating high-performance solar cells and monochromatic light-emitting diodes using solution-processed perovskite semiconductors is presented. n-i-p perovskite solar cells and perovskite nanocrystal light-emitting diodes (PNC-LEDs), with power-conversion and current efficiencies of 18.2% and 15.2cd A-1 , respectively, are demonstrated on ultrathin polymer substrates with high thermal stability, which is a record-high efficiency for ultraflexible perovskite solar cell. The narrowband EL with a full width at half-maximum of 23nm successfully eliminates FP interference, yielding bending-insensitive spectra even under 50% of mechanical compression. Photo-plethysmography using the skin optoelectronic device demonstrates a signal selectivity of 98.2% at 87bpm pulse. The results presented here pave the way to inexpensive and high-performance ultrathin optoelectronics for self-powered applications such as wearable displays and indoor IoT sensors.

Off-Grid Electrogenerated Chemiluminescence with Customized p-i-n Photodiodes.

Electrochemiluminescence (ECL) is the generation of light induced by an electrochemical reaction, driven by electricity. Here, an all-optical ECL (AO-ECL) system is developped, which triggers ECL by the illumination of electrically autonomous "integrated" photoelectrochemical devices immersed in the electrolyte. Because these systems are made using small and cheap devices, they can be easily prepared and readily used by any laboratories. They are based on commercially available p-i-n Si photodiodes (≈1€unit-1), coupled with well-established ECL-active and catalytic materials, directly coated onto the component leads by simple and fast wet processes. Here, a Pt coating (known for its high activity for reduction reactions) and carbon paint (known for its optimal ECL emission properties) are deposited at cathode and anode leads, respectively. In addition to its optimized light absorption properties, using the commercial p-i-n Si photodiode eliminates the need for a complicated manufacturing process. It is shown that the device can emit AO-ECL by illumination with polychromatic (simulated sunlight) or monochromatic (near IR) light sources to produce visible photons (425nm) that can be easily observed by the naked eye or recorded with a smartphone camera. These low-cost off-grid AO-ECL devices open broad opportunities for remote photodetection and portable bioanalytical tools.

Photobiomodulation in clinical practice

For the past few years, we have been witnessing a gradual, but rapid change in the management of skin wounds: the so-called 'advanced' dressings have been joined, and partly replaced, by interactive dressings, in which the dressing itself interacts with the wound bed and perilesional skin, modulating one or more aspects of the tissue repair mechanism through the interaction with cells, chemical mediators and factors hindering healing.
 The even more recent introduction of high-tech devices has definitively propelled Wound Care into the modern era of Tech Treatment, in which one or more technologies are employed in the management of the wound and the reparative process.
 In this field, Regenerative Medicine and Surgery represent the most recent frontier reached by this 'technological expansion', through the use of dermo/epidermal substitutes and material stimulating the healing process in its different phases.
 
 In the early 2000s, considerable interest was aroused by the attempt to apply 'phototherapy' to wound management: Taking their cue from the results obtained some time ago in the treatment of certain lesions, cutaneous and otherwise, neoplastic and not, with the use of Photodynamic Therapy (by means of red light and 5 amino-levulinic acid), a Florentine research group (to which some of the Authors of this paper belonged) began to study its effects on venous ulcers, with extremely encouraging results in terms of resumption of the reparative process, with evidence of increased angiogenesis, fibroblast number and antigen-presenting cells, amongst other things.
 Over the years, other types of biophotonic treatment have been developed, with the introduction of monochromatic light sources (red, green, blue), capable of selectively interacting with the different tissue chromophores, and of triggering effects (so-called photobiomodulation) in the treated tissues, which differ according to the wavelength used and the chromophores stimulated each time.
 More recent is the application of exogenous fluorophores, which can absorb radiant light and convert it into light of different wavelengths through a phenomenon known as fluorescence.
 The enormous therapeutic possibilities offered by different treatments have led to exciting results from a tissue regeneration point of view.
 However, as it often happens when a technology is affected by such sudden changes and developments, clinical practice currently suffers from certain biases, mainly related to the presence of uncoordinated protocols of use, for each technology, in the absence, therefore, of algorithms of use that would make their clinical application homogeneous, establishing, for each type of light stimulation, its role and real potential, setting its limits and indications, also on the basis of clinical risk.
 We felt it was time to sit around a table, bringing together some of the top experts in each field of this discipline, trying to clarify all the aspects that characterise the interaction of light with tissues, in a dialogue that brought together physicists, chemists, clinicians and experts in statistics and literature (among the best in the country, and with proven experience in the field in question), in order to find a common language and try to provide information for the correct indications for the use of this method of tissue regeneration, free from corporate and institutional influences, without any sponsorship and, above all, dictated by real experience developed in the various sectors, supported by data from Literature.

The impact of the duration of wave treatment on the development of yeast populations

Introduction: The scientific literature does not contain research on the influence of monochromatic light treatment on the development of bottom-fermenting beer yeast populations.Purpose: An analysis of the literature data allowed us to suppose the possibility of activating the development of the beer yeast Saccharomyces cerevisiae population through preliminary treatment with light of visible spectrum wavelengths, providing technological and economic efficiency of such an impact method on a production scale.Materials and Methods: The object of research was the process of cultivating a population of bottom-fermenting beer yeast Saflager S-189 (Fermentis). The subject was the influence of preliminary treatment of the seed yeast with monochromatic light with a wavelength of 980 nm on this process. Its effectiveness was assessed by the weight loss of the cultivation medium, the increase in the total cell titre, the proportion of unviable and "fed" cells. A KFK-2 photoelectrocolorimeter was used as a source of monochromatic light with wavelengths of the visible range. Seeding of mediums and sample preparation for analysis were performed in a BAVnp-01-"Laminar-S."-1.2 antibacterial air medium box. The yeast's fermenting activity was assessed by the weight loss of the nutrient medium; the total cell titre was established by counting in a Goryaev's chamber; the percentage of unviable cells was determined using methylene blue dye; the percentage of "fed" yeast cells was established by staining glycogen with iodine solution.Results: Preliminary treatment of the seed yeast with monochromatic light (980 nm) allowed increasing the fermenting activity of bottom-fermenting beer yeast by 10-15% compared to the control, which is consistent with the results of other research groups concerning populations of microorganisms of other genera and species. The values of other determined indicators - the proportion of "fed" and unviable cells, the total yeast cell titre - in the experimental variants were at the level of those in the control samples or slightly inferior to them. Data on the influence of the duration of seed yeast irradiation for 60, 120 or 180 minutes on the listed controlled indicators are presented, and the authors express the opinion about the appropriateness of its conduction for 60 minutes.Conclusion: The principle possibility of activating the development of a population of bottom-fermenting beer yeast by preliminary treatment of seed yeast with light with a wavelength of 980 nm, which can give an economic effect on an industrial scale, is substantiated; the necessity of testing the technological method under study in conditions close to production ones, i.e., for brewing wort with an irradiated suspension of seed yeast, is noted.

Three-dimensional modelling of blur property for conventional optical microscopes

Intensity diffusion caused by optical diffraction limits the imaging resolution of conventional optical microscopes, therefore modelling and measuring the intensity transmission and distribution property of the light sources is a significant research topic in system development and pattern recognition. However, the complicated wave propagation process in optical imaging makes it difficult to provide a direct, analytical and simple mathematical model to measure the relationship between the blur degree and various camera parameters. In this study, an improved intensity transmission and distribution calculation method for conventional optical microscopes was proposed; furthermore, a simple mathematical relation between the blur degree and camera parameters was achieved based on the proposed method. First, the light intensity distribution and propagation characteristics of a conventional optical microscope were modeled based on the property of the Fresnel circular hole diffraction combined with the practical optical parameters. Second, by analyzing the property of intensity distribution and blurring imaging, a quantitative simplified mathematical relationship between the blur degree and camera parameters in optical microscope imaging was obtained, and the three-dimensional (3D) blur property in the optical imaging process was analyzed under different conditions. Third, the connection between diffractive optics and geometric optics was obtained by summarizing and generalizing the 3D blur property curve of each monochromatic light source. Finally, the proposed method was verified through a series of simulations and experiments.

Interferometer response characterization algorithm for multi-aperture Fabry-Perot imaging spectrometers.

In recent years, the demand for hyperspectral imaging devices has grown significantly, driven by their ability of capturing high-resolution spectral information. Among the several possible optical designs for acquiring hyperspectral images, there is a growing interest in interferometric spectral imaging systems based on division of aperture. These systems have the advantage of capturing snapshot acquisitions while maintaining a compact design. However, they require a careful calibration to operate properly. In this work, we present the interferometer response characterization algorithm (IRCA), a robust three-step procedure designed to characterize the transmittance response of multi-aperture imaging spectrometers based on the interferometry of Fabry-Perot. Additionally, we propose a formulation of the image formation model for such devices suitable to estimate the parameters of interest by considering the model under various regimes of finesse. The proposed algorithm processes the image output obtained from a set of monochromatic light sources and refines the results using nonlinear regression after an ad-hoc initialization. Through experimental analysis conducted on four different prototypes from the Image SPectrometer On Chip (ImSPOC) family, we validate the performance of our approach for characterization. The associated source code for this paper is available from Zenodo (http://dx.doi.org/10.5281/zenodo.7978514).

Using a Diffraction Grid to Measure the Wavelength of a POF Laser

The research has been carried out to determine the wavelength of the POF laser using a diffraction grating. The diffraction grating used consists of three kinds of grid constants, namely 100 lines/mm, 300 lines/mm, and 600 lines/mm. Furthermore, the variation of the distance between the grid and the screen with a length of 40 cm, 60 cm, and 90 cm is carried out. The results showed that the wavelength of the POF laser light was between 664.07 nm-728.31 nm and the red monochromatic light source obtained the interference pattern of light on the screen as well as red monochromatic light. Based on the results of the research, it can be proven that the wavelength obtained from the use of a diffraction grating to measure the wavelength of the red laser is close to the wavelength value of 664.07 nm.

Optical properties of 3D printed orthodontic retainers

The orthodontic retainers, used after orthodontic treatment are mainly produced by thermoforming. Studies and knowledge regarding directly printed orthodontic retainers and their optical properties are limited. The optical properties were tested using a source of monochromatic light and a spectrometer, which measures the intensity of the light passing through the specimens at different wavelengths. The best optical properties are seen with thermoformed specimens, whereas with 3D printed specimens polishing diminished the intensity of light passing through. The transparency of thermoformed materials is superior to that of 3D printed ones. Polishing the materials reduced their optical properties. Despite the fact that less light is transmitted through the 3D printed specimens, the materials offer clinically acceptable and satisfying optical properties.