Intensity Of Optical Signal Research Articles

Extracting powder bed features via electron optical images during electron beam powder bed fusion

Electron beam powder bed fusion offers the unique opportunity to observe the process by measuring scattered electrons on a metal detector. This technique is the state of the art in generating electron optical images of the build area after melting using single- or multi-detector setups. The images enable the detection of surface defects like porosity or material transport by reconstructing the surface topography. Internal defects such as layer-bonding defects cannot be identified. Many of these defects, particularly layer-bonding defects, often originate from an irregular distribution of the powder bed.This work introduces an additional process step by recording an electron optical image after the distribution of the powder bed. Combining this with an electron optical image after melting the previous layer enables extraction of powder bed features such as the current powder bed height. The underlying method bases on the correlation of experimental measurements and numerical simulations of the intensity of the electron optical signal for different powder bed heights. With this approach, it is possible to identify irregular powder distributions, such as uncovered areas of previously molten material or locally varying powder bed heights. This information is crucial for online monitoring and real time process control. Exemplary, this opens the opportunity of healing the powder bed by an additional raking step.

Adjustable optical fiber displacement-curvature sensor based on macro-bending losses with a coding of optical signal intensity

In this work, a simple design and cost-effective displacement-curvature sensor based on macro-bend single-mode fiber (SMF) is planned and demonstrated. The optical fiber sensor encompasses a bending configuration and the macro-bending losses were exploited as the sensing process for the capturing of angular displacement motion in an angle span between 0° and 90° (that corresponds to curvature displacement between 0 and 49.5 cm). A straight SMF shape and other four bent sensor structures (U-like, drop-like, Knot-like, and eight-like) have been fabricated from sections of 90 cm length SMF. These five sensor configurations will provide high maneuvering for versatile applications. In these adjustable sensing schemes, the fiber sensors were described by monitoring the power loss corresponding to the diverse angular displacement at various bending structures in terms of the shape of the bend, the bending diameter, and the number of wrapping turns. Then, these measurement schemes based on the macro-bending losses were employed to detect the human motion elbow joint, and a proper sensing scheme was adopted to examine the flexion/extension joint motion in detail. The proposed sensors showed enhanced sensitivity to flexion/extension joint motion range between −0.25 and −0.477 dB/° and good sensitivity to curvature ranging between −0.552 and −1.052 dB/cm. The demonstrated and planned sensing techniques are adjustable and accessible for different types of human and mechanical movements.

DMSO synergized with sugars: optical clearing agent modulation of optical coherence tomography of skin tissues.

The stratum corneum of the outermost skin is an important barrier impeding transdermal permeation, and permeation enhancers can reduce the barrier resistance of the stratum corneum and enhance the permeation of drugs in tissues. The optical imaging depth, signal intensity, and scattering coefficient variation rules of skin tissues in time dimension are obtained by using optical coherence tomography (OCT). The effect of optical clearing agents (OCAs) on OCT imaging is obtained by quantitatively analyzing the changes in the optical properties of tissues. D-fructose, one of the monosaccharides, and sucrose, one of the disaccharides, were selected for the ex vivo optical clearing experiments on pig skin tissues utilizing the dimethyl sulfoxide (DMSO) carrier effect. We find that DMSO synergized with sugars applied to skin tissue has a more significant increase in the optical imaging depth and signal intensity, and a reduction in the scattering coefficient with an increasing concentration of DMSO. DMSO with a high concentration and D-fructose with saturated concentration (10:1; v/v) effectively reduce light attenuation in OCT imaging and improve the image quality. This operation will also shorten the application time to minimize skin damage from hyperosmotic agents.

Automatic Detection of Fiber Optic Gyroscope Intrinsic Frequency Based on Optimal Projection Approximation

To address the complexity and low detection accuracy issues in the intrinsic frequency detection process of fiber optic gyroscopes, a highly precise automatic measurement method based on optimal projection approximation is proposed. Building upon the digital closed-loop fiber optic gyroscope hardware circuit, this method generates a frequency-adjustable square wave with a 25% duty cycle through field-programmable gate array (FPGA) fractional division. Subsequently, it calculates the difference between the high and low levels of the sign bits of the modulated optical intensity signal sampled by the analog-to-digital converter (ADC). This yields an error signal related to the modulation frequency and intrinsic frequency. The modulation frequency is then approximated using the nearest projection of this error signal, thereby achieving automatic detection of the fiber optic gyroscope’s intrinsic frequency. The experimental results indicate that this method, requiring no external auxiliary equipment, enables rapid and highly accurate measurement of the intrinsic frequency of the fiber optic gyroscope. The measurement of intrinsic frequency takes approximately 300 milliseconds, achieving a measurement accuracy of up to 0.001 Hz.

Difunctional Magnetic Nanoparticles Employed in Immunochromatographic Assay for Rapid and Quantitative Detection of Carcinoembryonic Antigen.

Immunochromatographic assay (ICA) plays an important role in in vitro diagnostics because of its simpleness, convenience, fastness, sensitivity, accuracy, and low cost. The employment of magnetic nanoparticles (MNPs), possessing both excellent optical properties and magnetic separation functions, can effectively promote the performances of ICA. In this study, an ICA based on MNPs (MNP-ICA) has been successfully developed for the sensitive detection of carcinoembryonic antigen (CEA). The magnetic probes were prepared by covalently conjugating carboxylated MNPs with the specific monoclonal antibody against CEA, which were not only employed to enrich and extract CEA from serum samples under an external magnetic field but also used as a signal output with its inherent optical property. Under the optimal parameters, the limit of detection (LOD) for qualitative detection with naked eyes was 1.0 ng/mL, and the quantitative detection could be realized with the help of a portable optical reader, indicating that the ratio of optical signal intensity correlated well with CEA concentration ranging from 1.0 ng/mL to 64.0 ng/mL (R2 = 0.9997). Additionally, method comparison demonstrated that the magnetic probes were beneficial for sensitivity improvement due to the matrix effect reduction after magnetic separation, and the MNP-ICA is eight times higher sensitive than ICA based on colloidal gold nanoparticles. The developed MNP-ICA will provide sensitive, convenient, and efficient technical support for biomarkers rapid screening in cancer diagnosis and prognosis.

Dispersion of optical constants of Si:PbGeO crystal in the terahertz range

Objectives. Advances in laser physics over the last decade have led to the creation of sources of single-period electromagnetic pulses having a duration of about 1 ps, corresponding to the terahertz (THz) frequency range and a field amplitude of several tens of MV/cm. This allows the electrode-free application of an electric field to a ferroelectric for observing not only the excitation of coherent phonons, but also ultrafast (at the sub-picosecond timescale) dynamic polarization switching. To detect polarization switching, a pump-probe technique is used in which a THz pulse is used with an optical probe. Since its intensity is proportional to the square of the polarization, the signal of the optical second harmonic is used to measure polarization switching under the action of a THz pulse. To evaluate switching efficiency, both linear (refractive index and absorption coefficient) and non-linear optical characteristics (quadratic and cubic susceptibilities) are required. For any application of ferroelectric crystals in the THz range, knowledge of the relevant linear optical characteristics is also necessary.Methods. The technique of THz spectroscopy in the time domain was used; here, a picosecond THz pulse transmitted through the crystal is recorded by strobing the detector with a femtosecond optical pulse. The THz-induced dynamics of the order parameter in a ferroelectric was studied by detecting the intensity of a nonlinear optical signal at the frequency of the second optical harmonic.Results. The transmission of a THz wave and the intensity of second harmonic generation on a lead germanate crystal doped with silicon in the time and spectral domains were measured. On this basis, the absorption coefficient dispersion and cubic nonlinear susceptibility were calculated in the range of 0.5-2.0 THz. The presence of a region of fundamental absorption near the phonon modes was confirmed along with a resonant enhancement of the cubic nonlinear susceptibility for two phonon modes Ω1 = 1.3 THz and Ω2 = 2.0 THz.Conclusions. The proposed technique is effective for analyzing the dispersion of the optical characteristics of ferroelectric crystals. The significantly improved spectral resolution (0.1 THz) increases the accuracy of determining nonlinear susceptibility due to the detailed analysis of the linear and nonlinear contributions to the second harmonic intensity.

Abstract 14241: Feasibility and Safety of Non-Contrast Optical Coherence Tomography Imaging Using Hydroxyethyl Starch in Coronary Arteries

Background/Objectives: Contemporary high-resolution intracoronary optical coherence tomography (OCT) requires injection of flushing media for image acquisition. There is a growing need for an alternative flushing media other than iodine contrast to reduce the risk of acute kidney injury. To address this issue, we investigated the safety and feasibility of hydroxyethyl starch (pentastarch) as a flushing media for OCT image acquisition and compared with the contrast media flushed images. Methods: We prospectively enrolled 43 patients with 70 coronary lesions (46 stented and 24 pre-stented or non-culprit lesions). Paired OCT images were obtained by manual injection of iodine contrast (average 12 mL), followed by pentastarch (average 15 mL). A total of 162 runs (81 pairs) were analyzed and each OCT pullback was assessed on a frame-by-frame basis by automated customized lumen contour and stent strut segmentation algorithm. Results: Image quality as assessed by proportion of clear image segments were comparable between the contrast media and pentastarch flushed images (93.3% vs. 93.7%; p=0.501). Pixel-based flushing capability showed no significant difference between the paired image segments (median(IQR), 0.951(0.947-0.953) vs. 0.951(0.949-0.952), p=0.264; Figure). Quantitative measurements of minimal stent area (R 2 =0.977, p<0.001), minimal lumen area (R 2 =0.983, p<0.001) correlated well between the paired OCT runs. There were no clinically relevant complications associated with OCT imaging with pentastarch such as anaphylaxis, life-threatening arrhythmia, or acute renal deterioration. Conclusions: Intracoronary OCT using pentastarch is safe and technically feasible without affecting the optical signal intensity and overall image quality. Non-contrast imaging with pentastarch significantly reduces the obligatory iodine contrast load, therefore, could be considered as a promising strategy in high-risk patients for renal impairment.

Cystatin C as a biomarker for cardiorenal syndrome diseases quantitative diagnostics and monitoring via point-of-care.

With heart failure (HF) and renal malfunction becoming global public health issues, there is an urgent need to monitor diseases at home or in the community. Point-of-care testing (POC) would shorten the patients waiting time compared with laboratory molecular analysis. This work evaluates two types of gold nanomaterials, and two assay protocols, to develop a lateral flow (LF) system for Cystatin C (CysC) quantification. Of the protocols, the 'delayed-release' shows the alleviation of the hook effects with 1% BSA running buffer (RB), albeit at increased complexity with three steps of washing. The standard method with sample dilution (1: 150 sample dilution for GNPs, and 1:10 sample dilution for GNRs) can ensure the clinical range detection of CysC as 1 mg/L with partial LF assays. GNPs have stronger optical signal intensity compared with GNRs and developed full LF assays with GNPs require 1:1.5 sample dilution in recombinant Cys C detection. The ideal sample dilution ratio is different for partial and full LF assays. Clinical Relevance- This work is the basis of future work that will use LF devices for human serum/plasma monitoring to assess kidney function related to heart failure during medication. The specificity, sensitivity, and limit of detection will be validated via a clinical trial before potential clinical use.

Probability of Erroneous Data Registration in a Single Photon Erasure-Type Communication Channel with a Receiver Based on a Photon Counter

When measuring low-power optical signals, it is necessary to ensure the highest reliability of the received data, which is especially important for single-photon communication channels. This determines the expediency of using photon counters as receiving modules for such channels. They are highly sensitive, but are characterized by data recording errors. Therefore, the purpose of this work was to investigate the influence of the intensity of the registered optical radiation J0 during the transmission of binary symbols “0” on the probability of registering symbols “1” at the output of the communication channel in the presence of symbols “0” at its input P(1/0).The statistical distributions of the mixture of the number of dark and signal pulses at the output of the photon counter during the registration of binary symbols “0” Pst0 (N ) were determined. To do this, a technique was used to reduce information loss. As a result, the minimum probability P(1/0) was reached.The probabilities P(1/0) were calculated for a communication channel containing a photon counter as a receiving module. This calculation was carried out at different values of the supply voltage of the avalanche photodetector U and the intensity of the optical signal used to transmit the binary symbols “0” J0 .The experimental results showed that with increasing optical signal intensity J0 , the dependences P(1/0) on J0 initially remain almost unchanged and retain a constant value. However, with a further increase in J0 , there is a linearly increasing character of the dependences P(1/0) on J0 . Moreover, with other equal reception parameters, such a character of the dependences P(1/0) on J0 begins to manifest itself at higher intensities of the optical signal J0 with an increase in the supply voltage of the avalanche photodetector.

Optical signal intensity incorporated rice seed cultivar classification using optical coherence tomography

Here, the optical signal intensity of swept-source optical coherence tomography (SS-OCT) was incorporated to assess the images of different rice seeds for precise cultivar classification. Such classification is essential from various agricultural viewpoints but remains challenging because rice seeds have a similar visual appearance. Thus, studies on rice seed cultivar classification play a key role in achieving a successful rice yield. To investigate the feasibility of the proposed approach, two-dimensional OCT images were acquired from two types of rice seed cultivars (Chucheong and Hopyeong), which were then subjected to an optical signal intensity assessment. Based on the depth-dependent optical scan profile results, the averaged and normalized back-scattered light intensity curves revealed a distinct difference between each cultivar, which aided the precise classification of the cultivars. Therefore, the developed optical signal-sensing approach can be extensively applicable to seed cultivar classification in the agricultural industry.

Peptide-Encapsulated Single-Wall Carbon Nanotube-Based Near-Infrared Optical Nose for Bacteria Detection and Classification

Sense of smell has been used as a diagnostic tool for almost entire human history. While successful examples of the use of the human nose for diagnostics are rare in modern history, there are ample reports of use of animals to diagnose various medical conditions. Bacterial infections often result in strong odors. In recent years, electronic noses (e-nose) and optical noses (o-nose) are of high interest in diagnostics and classification of bacterial infections. Artificial olfactory sensors can perform noninvasively, immediately at the point of care, do not require extensive sample handling, and promise to be highly cost-effective. This manuscript demonstrates the development of a near-infrared optical sniffer comprised of peptide-encapsulated (6,5) single-wall carbon nanotubes (SWCNTs) for bacteria detection and classification. Sixteen different peptides that include tyrosine in different proportions and positions were synthesized. The ability of these peptides to disperse SWCNTs in water was tested, and the intensity of the resultant optical signal was evaluated. Overall, longer peptides provided better dispersion as compared to shorter peptides. Addition of the fluorenylmethyloxycarbonyl chloride (Fmoc) group to positively charged peptides tested in the current study significantly improved SWCNT dispersion and signal intensity. The sensors successfully distinguished between the odor of sterile growth medium, Escherichia coli, and Klebsiella pneumoniae. Moreover, we demonstrated the possibility of using the developed sensors for antibiotics susceptibility testing. The sensors provided results in real-time, enabled multiple-usage, and operated at room temperature.

Research on RP-EDF amplification characteristics based on φ-OTDR system

Extending the sensing distance is of great significance for expanding the application of phase-sensitive optical time-domain reflectometry (φ-OTDR) in remote perimeter monitoring. Due to the inevitable fiber loss, the optical signal intensity decays exponentially with the length of the sensing fiber, and the sensing distance is greatly limited. In this study, a remote-pumped single-ended incident optical signal amplification scheme using erbium-doped fiber (EDF) is reported, and the factors affecting the amplification effect are comprehensively investigated. The experimental results show that the optimal amplification effect can be achieved when the input signal optical power is − 20 dB, the input signal optical wavelength is 1550 nm, the pump power is 100 mW and the erbium-doped fiber length is 10 m.

Rapid and direct concentration range judgment of lamotrigine in plasma by the multi test lines with different detection limits on the same lateral flow strip

Continuous and interval monitoring of target drug concentration is of great importance for the effective and controllable therapy of diseases. In this research, the colloidal gold labeled lateral flow strip (LFS) is utilized for rapid and direct judgement of lamotrigine (LTG) concentration range, a specific medicine for epilepsy with the effective therapeutic concentration from 2.5 to 15 μg/mL in serum (corresponding to 25–150 ng/mL after 100-time dilution). Interestingly, two test lines of different detection limits on the same LFS can show different optical signal intensities at the same concentration of LTG in serum. Therefore, for concentration range judgment, it can be directly judged by the combination results of the two test lines on the same LFS without aid of any instruments. Typically, just with the dilution treatment of serum samples for 100 times, three concentration ranges including 0–25 ng/mL, 25–150 ng/mL, and higher than 150 ng/mL can be easily distinguished by the different test line combination results on the same LFS. The clinical serum samples at different concentrations of LTG have also been successfully measured with this multi detection limits LFS, which is 100% consistent with those of the HPLC. The simple operation and judgement standards of LFS with multi detection limits will make the home-test or self-test of therapeutic drug monitoring possible.

Abstract 12618: Feasibility of Non-Contrast Optical Coherence Tomography Imaging in Coronary Arteries

Background/Objectives: Contemporary high-resolution intracoronary optical coherence tomography (OCT) requires injection of flushing media for image acquisition to avoid signal attenuation by red blood cells. There is a growing need for an alternative flushing media other than iodine contrast to reduce the risk of renal dysfunction. To address this issue, we investigated the safety and feasibility of pentastarch solution as a flushing media for OCT image acquisition and compared with the contrast media flushed images. Methods/Results: We prospectively enrolled 12 patients with 15 coronary lesions (12 stented lesions and 3 non-culprit lesions). Paired OCT images were obtained by manual injection of iodine contrast (average 12 mL), followed by pentastarch (average 18-20 mL). A total of 30 runs were analyzed and each OCT pullback was assessed on a frame-by-frame basis by automated customized pixel-wise comparison algorithm. The number of clear image segments (CIS) and pre-specified quantitative measurements were compared between the paired OCT images. Image quality as assessed by proportion of CIS showed no significant difference between the contrast media and pentastarch (98.5% vs. 97.5%; p=0.850). Quantitative measurements including minimal lumen area, mean lumen area, and pixel-wise blood flushing capability correlated well between the paired image segments (p<0.001) (Figure). There were no clinically relevant complications associated with OCT imaging with pentastarch administration such as anaphylactic reaction, life-threatening arrhythmia, heart failure, or acute renal deterioration. Conclusions: Intracoronary OCT using pentastarch is safe and technically feasible without affecting the optical signal intensity and overall image quality. Non-contrast imaging with pentastarch significantly reduces the obligatory iodine contrast load, therefore, could be considered as a promising strategy in high-risk patients for renal impairment.

Quantitative measurement of disturbances based on optical-fibre multiparameter optimization method

Phase-sensitive optical time domain reflectometry (φ-OTDR) has been applied in security monitoring. However, φ-OTDR cannot directly measure strain and intensity of an applied disturbance, thereby limiting the choice of features for intrusion pattern recognition and hazard assessment. This paper proposes a quantitative method to measure disturbances using amplitude-based φ-OTDR. The optical-fibre multiparameter optimization (FMPO) method is developed. The FMPO analyses the curve pattern of optical intensity signals to calculate strain. No extra module is needed, instead a specially designed bio-inspired algorithm is introduced. Quantification indices to gauge disturbance intensities are derived for practical use. A piezoelectric ceramic cylinder test demonstrated a linear correlation between the quantification indices and the vibration amplitude (R2 = 0.8956). The calculated strains of 34 driven voltages agreed well with theoretical values within 1000 nε. In a pendulum-impact experiment, five intrusion intensities were successfully identified, which indicated that FMPO performed well in the field.

Direct modulation of microwave by visible light based on graphene microstrip patch antenna

A method for modulating microwave directly by visible light based on a graphene microstrip patch antenna is proposed. In the antenna, the microwave radiation is modulated with the variation of visible light intensity when both are interacting with the graphene layer. Simulation results indicate that the S11 coefficient of the microwave radiation can change by 20 dB if the Fermi level of graphene varies from 0.1 eV to 0.5 eV when it is radiated by the antenna. With normal incidence, the experimentally measured microwave modulation depth of the S11 coefficient is 1.3 dB when the intensity of the modulation light is 100 mW at the wavelength of 532 nm. The result indicates that the graphene microstrip patch antenna is capable of converting optical intensity signal to microwave intensity signal directly.

Performance of transmitted optical fiber hydrogen sensing system based on orthogonal demodulation method

A transmitted optical fiber sensing system based on orthogonal demodulation algorithm is used for hydrogen detection in this paper. WO3/Pt fabricated by sol–gel method was used as sensing material. WO3 film reacts with hydrogen by the catalysis of Pt and refractive index of the sensing film changed, by measuring the transmitted optical power the concentration of hydrogen can be detected. Orthogonal demodulation algorithm was used to demodulate the weak transmitted optical intensity signals. Compared with the traditional ratio-type transmitted optical fiber hydrogen sensing system, the noise reduced by 28 times. The limit of detection is 495ppm and with good repeatability and stability. In order to improve the sensitivity of the system, three pieces of sensing film were used to increase the interaction length of the sensing material with hydrogen and the sensitivity increased by 2.592 times. With the orthogonal demodulated technique and multi pieces of sensing film, high sensitivity, fast response and low cost hydrogen sensing system was implemented and is very promising for the monitoring of hydrogen leakage in the field of hydrogen production, transportation, and storage.

An optical synapse based on a polymer waveguide with a GST225 active layer

This paper presents the results of an experimental study, implementation, and numerical simulation of the transmissivity of a polymer waveguide covered by a GST225 thin film with various phase states. The paper considers an optical synapse prototype based on the interface between the waveguide and an optically controlled GST225 film. We demonstrate the fundamental possibility of controlling an optical signal in the telecommunication C-range as it passes through the synaptic interface via the action of an external laser on an optically active GST225 film. Experimentally, 40% single- and multi-level modulations of the optical signal intensity are achieved. The numerical simulation results are in line with the experimental data. Based on this principle, next-generation all-optical storage and computing devices that simulate the properties of biological synapses and neurons can be developed.

Radiopharmaceutical and Eu3+ doped gadolinium oxide nanoparticles mediated triple-excited fluorescence imaging and image-guided surgery

Cerenkov luminescence imaging (CLI) is a novel optical imaging technique that has been applied in clinic using various radionuclides and radiopharmaceuticals. However, clinical application of CLI has been limited by weak optical signal and restricted tissue penetration depth. Various fluorescent probes have been combined with radiopharmaceuticals for improved imaging performances. However, as most of these probes only interact with Cerenkov luminescence (CL), the low photon fluence of CL greatly restricted it’s interaction with fluorescent probes for in vivo imaging. Therefore, it is important to develop probes that can effectively convert energy beyond CL such as β and γ to the low energy optical signals. In this study, a Eu3+ doped gadolinium oxide (Gd2O3:Eu) was synthesized and combined with radiopharmaceuticals to achieve a red-shifted optical spectrum with less tissue scattering and enhanced optical signal intensity in this study. The interaction between Gd2O3:Eu and radiopharmaceutical were investigated using 18F-fluorodeoxyglucose (18F-FDG). The ex vivo optical signal intensity of the mixture of Gd2O3:Eu and 18F-FDG reached 369 times as high as that of CLI using 18F-FDG alone. To achieve improved biocompatibility, the Gd2O3:Eu nanoparticles were then modified with polyvinyl alcohol (PVA), and the resulted nanoprobe PVA modified Gd2O3:Eu (Gd2O3:Eu@PVA) was applied in intraoperative tumor imaging. Compared with 18F-FDG alone, intraoperative administration of Gd2O3:Eu@PVA and 18F-FDG combination achieved a much higher tumor-to-normal tissue ratio (TNR, 10.24 ± 2.24 vs. 1.87 ± 0.73, P = 0.0030). The use of Gd2O3:Eu@PVA and 18F-FDG also assisted intraoperative detection of tumors that were omitted by preoperative positron emission tomography (PET) imaging. Further experiment of image-guided surgery demonstrated feasibility of image-guided tumor resection using Gd2O3:Eu@PVA and 18F-FDG. In summary, Gd2O3:Eu can achieve significantly optimized imaging property when combined with 18F-FDG in intraoperative tumor imaging and image-guided tumor resection surgery. It is expected that the development of the Gd2O3:Eu nanoparticle will promote investigation and application of novel nanoparticles that can interact with radiopharmaceuticals for improved imaging properties. This work highlighted the impact of the nanoprobe that can be excited by radiopharmaceuticals emitting CL, β, and γ radiation for precisely imaging of tumor and intraoperatively guide tumor resection.

Assessment of the influence of intensity of optical signal on the probability of erroneous data registration in a single-photon communication channel

When measuring low-power optical signals in single-photon communication channels, the receiving modules must ensure the minimum probability of erroneous data recording. In this regard, it is advisable to use photon counters. They are highly sensitive, but are characterized by data recording errors. The aim of the work was to determine the effect of intensity of optical signal on the probability of erroneous data recording in a single-photon communication channel with a receiving module based on a photon counter.Based on the results of experimental studies, the dependences of the probability of erroneous registration of binary symbols «0» Perr 0 on the intensity of the optical signal J0 , used to transmit these symbols for various supply voltages of the avalanche photodetector U, were obtained. It was found that with an increase of intensity of the optical signal, the dependences Perr 0(J0) first decrease, reaching their lowest value, and then increase. The performed assessment showed that the lowest probability of erroneous registration the binary symbols «0» for the investigated communication channel is equal to 17,56 • 10-2 and corresponds to J0 = 52,41 • 10-2 rel. units and U = 52,54 V.