High-sensitivity Camera Research Articles

Time Resolved Observation of Streamer Discharges in Dielectric Barrier Discharge by Highly Sensitive Camera and Image Analyzing Procedure

ABSTRACT In dielectric barrier discharge (DBD) type ozone generators, improving energy efficiency, or ozone generation efficiency, is an active field of research. In ozone generation by a DBD device, numerous micro-discharges consisting of streamer channel and surface discharge are generated in a discharge gap, and ozone is generated in these discharges. Since streamer channel and surface discharge are considered to affect ozone generation characteristics, it is important to quantitatively evaluate the generation aspects of these discharges. In this study, we developed a method to extract streamer channel and surface discharge from the grayscale value distribution of the micro-discharges photograph taken from the top side of the DBD device, which consists of a transparent high voltage electrode and a metal electrode, using an image-analyzing procedure and a high-sensitivity camera equipped an image intensifier. In the method, by applying appropriate thresholding methods, binary images of micro-discharges and streamer channels can be generated from the micro-discharge photograph. Statistical analysis of these binary images enabled the estimation of the average projected area diameters of streamer channels and the average lengths of surface discharges. This approach also allowed for time-resolved observations of the number of streamer channel per unit discharge area (streamer channel density), their average projected area diameter, and the average length of surface discharge. The findings from time resolved observation revealed that a positive correlation between the streamer channel density and the magnitude of the discharge current density. Moreover, the magnitude or polarity of the discharge current did not influence the average projected area diameter of streamer channels. However, the average length of surface discharge slightly decreased with increasing streamer channel density.

Dual-cameras terahertz imaging with multi-kilohertz frame rates and high sensitivity via Rydberg-atom vapor

Abstract Terahertz (THz) imaging holds increasing importance across various scientific fields and practical applications due to its unique characteristics. However, achieving high sensitivity and high frame rates simultaneously remains a major challenge for most current THz imaging techniques. In this paper, we demonstrate an improved THz imaging system based on Rydberg-atom vapor, which converts THz waves into visible fluorescence. A high-sensitivity camera and a high-speed camera are used simultaneously to capture the visible fluorescence. Specifically, for a 0.55 THz source, a sensor with a minimum detectable power of 41.7 aW/μm² at 100 fps and 43 fW/μm² at 6000 fps has been achieved simultaneously, with an effective imaging area larger than 100 mm². To demonstrate the spectral properties, the measured spectrum of the emitted fluorescence is presented with a high resolution of 0.1 nm. The demonstrated system can promote the development of the Rydberg-atom vapor based THz imaging technique to practical THz imaging frontier applications.

High sensitivity cameras can lower spatial resolution in high-resolution optical microscopy

High-resolution optical fluorescence microscopies and, in particular, super-resolution fluorescence microscopy, are rapidly adopting highly sensitive cameras as their preferred photodetectors. Camera-based parallel detection facilitates high-speed live cell imaging with the highest spatial resolution. Here, we show that the drive to use ever more sensitive, photon-counting image sensors in cameras can, however, have detrimental effects on the spatial resolution of the resulting images. This is particularly noticeable in applications that demand a high space-bandwidth product, where the image magnification is close to the Nyquist sampling limit of the sensor. Most scientists will often select image sensors based on parameters such as pixel size, quantum efficiency, signal-to-noise performance, dynamic range, and frame rate of the sensor. A parameter that is, however, typically overlooked is the sensor’s modulation transfer function (MTF). We have determined the wavelength-specific MTF of front- and back-illuminated image sensors and evaluated how it affects the spatial resolution that can be achieved in high-resolution fluorescence microscopy modalities. We find significant differences in image sensor performance that cause the resulting spatial resolution to vary by up to 28%. This result shows that the choice of image sensor has a significant impact on the imaging performance of all camera-based optical microscopy modalities.

Real-time imaging of intracellular deformation dynamics in vibrated adherent cell cultures.

Mechanical vibration has been shown to regulate cell proliferation and differentiation in vitro and in vivo. However, the mechanism of its cellular mechanotransduction remains unclear. Although the measurement of intracellular deformation dynamics under mechanical vibration could reveal more detailed mechanisms, corroborating experimental evidence is lacking due to technical difficulties. In this study, we aimed to propose a real-time imaging method of intracellular structure deformation dynamics in vibrated adherent cell cultures and investigate whether organelles such as actin filaments connected to a nucleus and the nucleus itself show deformation under horizontal mechanical vibration. The proposed real-time imaging was achieved by conducting vibration isolation and making design improvements to the experimental setup; using a high-speed and high-sensitivity camera with a global shutter; and reducing image blur using a stroboscope technique. Using our system, we successfully produced the first experimental report on the existence of the deformation of organelles connected to a nucleus and the nucleus itself under horizontal mechanical vibration. Furthermore, the intracellular deformation difference between HeLa and MC3T3-E1 cells measured under horizontal mechanical vibration agrees with the prediction of their intracellular structure based on the mechanical vibration theory. These results provide new findings about the cellular mechanotransduction mechanism under mechanical vibration.

Fluorescence microscopy for brain activity imaging: one-photon microscopy and its application to pharmacological research

The development of genetically-encoded fluorescent probes for the detection of intracellular calcium ions and various neurotransmitters has progressed significantly in recent years, and there is a growing need for techniques that rapidly and efficiently image these signals in the living brain for pharmacological studies of the central nervous system. In this article, we discuss one-photon fluorescence microscopy techniques used for brain activity imaging, particularly wide-field imaging and head-mounted miniaturized microscopy, and introduce their basic principles, recent advances, and applications in pharmacological research. Wide-field calcium imaging is suitable for mesoscopic observation of cortical activity during behavioral tasks in head-fixed awake mice, while head-mounted miniaturized microscopes can be attached to the animal's head to image brain activity associated with naturalistic behaviors such as social behavior and sleep. One-photon microscopy allows for the development of a simple and cost-effective imaging system using an affordable excitation light source such as a light-emitting diode. Its excitation light illuminates the entire field of view simultaneously, making it easy to perform high-speed imaging using a high-sensitivity camera. In contrast, the short wavelength of the excitation light limits the field of observation to areas on or near the brain surface due to its strong light scattering. Moreover, the out-of-focus fluorescence makes it difficult to obtain images with a high signal-to-noise ratio and spatial resolution. The use of one-photon microscopy in brain activity imaging has been limited compared to two-photon microscopy, but its advantages have recently been revisited. Therefore, this technique is expected to become a useful method for pharmacologists to visualize the activity of the living brain.

Preliminary study of luminescence phenomena from various materials under ultra-high dose rate proton beam irradiation for dose management

This research aimed to identify materials capable of emitting visible light useful for dose management at ultra-high dose rate (uHDR). Various materials were irradiated with proton beams at a normal dose rate (NDR) and uHDR, and the resulting surface luminescence was captured using a high-sensitivity camera. The luminescence images were compared with the corresponding dose distributions. The luminescence of Tough Water Phantoms (Kyoto Kagaku Co. Ltd.) with various thicknesses was also observed to evaluate the depth distributions. Dose distributions were measured using two-dimensional ionization chamber detector arrays. The Tough Bone Phantom (Kyoto Kagaku Co. Ltd.) exhibited the strongest luminescence among the materials, followed by the Tough Water Phantom. The metals exhibited relatively weak luminescence. The luminescence profiles of the Tough Water Phantom, water, the Tough Lung Phantom (Kyoto Kagaku Co. Ltd.), and an acrylic were similar to the dose profiles. The luminescence distribution of the Tough Water Phantom in the depth direction was similar to that of the dose distributions. The luminescence at uHDR and NDR were approximately equivalent. The Tough Water Phantom was found to be a suitable material for dosimetry, even at uHDR. More detailed measurement data, such as wavelength data, must be collected to elucidate the luminescence mechanism.

A comparative study of EM-CCD and CMOS cameras for particle ion trajectory imaging

High-resolution and real-time imaging of particle ion trajectories is essential in nuclear medicine and nuclear engineering. One potential method to achieve high-resolution real-time trajectory imaging of particle ions involves utilizing an imaging system that integrates a scintillator plate with a magnifying unit and a cooled electron multiplying charge-coupled device (EM-CCD) camera. However, acquiring an EM-CCD camera might prove challenging due to the discontinuation of CCD sensor manufacturing by vendors. As an alternative imaging approach, a low-noise, high-sensitivity camera utilizing a cooled complementary metal-oxide-semiconductor (CMOS) sensor offers a promising solution for imaging particle ion trajectories. Yet, it remains uncertain whether CMOS-based cameras can perform as effectively as CCD-based cameras in capturing particle ion trajectories. To address these concerns, we conducted a comparative analysis of the imaging performance between a CMOS-based system and an EM-CCD-based system for capturing alpha particle trajectories. The results revealed that both systems could image the trajectories of alpha particle, but the spatial resolution with the CMOS-based camera exceeded that of the EM-CCD-based camera, primarily due to the smaller pixel size of the sensor. While the signal-to-noise ratio (SNR) of the trajectory image from the CMOS-based camera initially lagged behind that from the EM-CCD-based camera, this disparity was mitigated by implementing binning techniques on the CMOS-based camera images. In conclusion, our findings suggest that a cooled CMOS camera could serve as a viable alternative for imaging particle ion trajectories.

Atomic-scale imaging of electron sensitive zeolites with aberration corrected transmission electron microscopy

The spatial resolution of transmission electron microscopes (TEMs) and scanning transmission electron microscopes (STEMs) has been drastically improved by introducing aberration correction. However, observable range in electron sensitive zeolites are still limited due to electron irradiation damages. Nevertheless, atomic resolution imaging of some zeolites is currently being realized by various developments in electron microscopic hardware, such as high sensitivity cameras. On the other hand, surveying the status of TEM and STEM imaging is very important for further progress in the structural analysis of zeolites. Here, we demonstrate and compare the high-resolution imaging of zeolites with several kinds of imaging modes.

Novel Method to Obtain Contact Angles of Tumor Biopsies.

Characterizing the strength of a solid-liquid interface can be done by depositing a single drop of liquid on a planar solid surface and measuring the angle of the formed semicircle, called the contact angle. The contact angle of pure water is indicative of a surface's hydrophobicity and is a useful metric in biomedical applications such as tissue scaffolding and drug/tissue interactions. However, the roughness and inhomogeneity of most biological surfaces make obtaining accurate contact angles of such materials challenging. Here, we developed an instrument and methodology to obtain contact angles of tissue sections. Breast cancer tumor and nearby healthy tissue sections were used as the model biological surface. The custom instrument was built on existing equipment by improving drop dispensing accuracy in the nanoliter range, an XYZ stage, additional side view cameras, and microscope-based sample visualization. The method takes into account the inherent surface inhomogeneity and topology of tissue and the required method of illumination for contact angle acquisition. As such, the system uses an inverted microscope with a high sensitivity camera, an XYZ stage for accurate droplet placement on tissue, and multiple cameras to obtain contact angles around the entire perimeter of the drop. We tested the system with breast cancer biopsies and adjacent normal tissue from 75 patients and report here a trend of tumor exhibiting higher water contact angles, and thus higher hydrophobicity, compared to their respective normal adjacent tissue. The system described here can be used to characterize any type of biological tissue, which can be sectioned, with any liquid including water or solutions with dissolved or suspended therapeutic molecules and particles.

Three-dimensional numerical evaluation of skin surface thermal contrast by application of hypothermia at different depths and sizes of the breast tumor

Background and Objective: Thermal procedures can provide improvements in the thermal contrast of thermographic images in an attempt to diagnose early cases of breast cancer. This work aims to analyze the thermal contrast of different stages and depths of breast tumors from hypothermia treatment using an active thermography analysis. The influence of variation in metabolic heat generation and adipose tissue composition on thermal contrasts is also analyzed.Methods: The proposed methodology was based on the solution of the Pennes equation for a three-dimensional model similar to the real anatomy of the breast by commercial software COMSOL Multiphysics. The thermal procedure consists of three steps: Stationary, hypothermia and thermal recovery. During hypothermia, the boundary condition of the external surface was replaced by a constant temperature of 0, 5, 10, and 15 ∘C, simulating a gel pack, for cooling times of up to 20 min. In the thermal recovery, after the removal of the cooling, the breast was submitted again to the condition of natural convection on the external surface.Results: Thermal contrasts in superficial tumors, for all hypothermia resulted in improvements in thermographs. For smallest tumor, the use of high resolution and sensitive thermal imaging cameras to acquire this thermal change may be necessary. For tumor of diameter of 10 cm, cooling from 0 ∘C can increase the thermal contrast by up to 136% compared to the passive thermography. Analyzes with deeper tumors showed very small temperature variations. Even so, the thermal contrast gain in cooling at 0 ∘C for the tumor with a diameter of 1 cm reached 37% in relation to passive thermography.Conclusions: Thus, this work contributes as an important tool in the analysis of the appropriate use of hypothermia for different cases in early stages of breast cancer, considering that long times are needed to obtain the best thermal contrast.

Employment of astronomical cameras ZWO ASI120MM for investigation of molecular light scattering

Molecular light scattering – the method allow to determine the intensity and coefficient of scattering of the substance. For most of aqueous solutions, the value of this coefficient is comparable to that for benzene, but an order of magnitude more than for water. Therefore, it is necessary to register the emitting intensity of the order of . For provide such experiments it has been proposed to used the high sensitive astronomical cameras, for eliminate interference, which allowed with physical-chemical processes. The aim of this work is to apply the high sensitive cameras ZWO ASI120MM in the investigation of molecular light scattering. In astronomical research for study the objects with weak light flows (comets, meteors, asteroids), usually used the CCD-cameras. For comparison three types of cameras, which used in the astronomical observations, are given. The CCD-camera VIDEOSCAN-415-2001 has been used for observation of the comets and asteroids, it has a small sizes and can to accumulate the signal without a system of refrigeration. The camera Watec WAT-902H2 ULTIMATE has high sensitive, that allow to fix the fast flying astronomical objects, meteors for example. The CCD-camera DMK 21AU04.AS, which is an analogue of ZWO ASI120MM, has been used for registration of fast processes. This article shows a successful application of the astronomical cameras ZWO ASI120MM in the investigation of molecular light scattering. The scheme of experimental setup using that camera is presented. It is shown that as a result of the experiments, it is possible to determine the intensity of the refracted and main ray and calculate the scattering coefficient for the solutions under study. For work with images obtained as a result of experiments, special software has been created. The developed program “Light” is allowed to conduct to measure the average value of the intensity. In the course of subsequent experiments, when setting new tasks, the software will be refined and improved. In the future, it is planned to use this technique for investigation the water-protein solutions.

A study both to measure and to visualize the scattering of fine particles generated during dental treatment

There is an urgent need to examine the risk of infection from aerosols generated during dental treatment and to review infection control. However, existing research on aerosol particles associated with dental treatment is by no means sufficient, and little research has been done on the details of aerosol particle generation in the clinical environment, the mechanisms, and patterns of distribution in open and closed spaces, the time they are suspended in the air, the amount and size of particles present. Therefore, to minimize the influence of background particles, laser beams, a high-sensitivity camera, and a particle counter were used in a large super-clean laboratory (SCL) to investigate the dynamics of aerosols generated during dental micromotor operation. The large number of aerosol particles generated by the use of the micro-engine rose rapidly within 30 seconds and were suspended in the room atmosphere. Within a 100 cm radius of the user, the scattering peaked at about 90 seconds. The particles were further diffused into the room with the passage of time, reaching a maximum at 210 seconds and gradually decreasing thereafter, confirming that the 4 x 4 m room had returned to equilibrium. The experiment was conducted under sealed conditions in the SCL without the use of any suction device inside or outside the oral cavity. Although the conditions did not faithfully reproduce the actual conditions in a dental clinic, we were able to obtain groundbreaking results that demonstrated for the first time the scattering of fine particles, eliminating various possible complications in the background. At present, our knowledge of the infectivity of COVID-19 from patients' oral cavity and saliva is still insufficient, and further studies and information are needed.

The impact of oxygen supply flow rates on the distribution of aerosols between the patient and the surgeon during lung intubation

The outbreak of COVID-19 has caused a worldwide pandemic. The widespread infection of the medical staff has caused great attention from all quarters of society. There is a particular concern when considering intubation treatment in the emergency operating room, where a significant amount of virus droplets are typically spread within the room, exposing the medical staff to a high risk of infection. Hence, there is currently a pressing need to develop an effective protection mechanism for the medical staff to prevent them from being infected during routine work. In order to understand the spread of droplets and aerosols when different oxygen supply devices are used for intubation therapy, this study uses particle image velocimetry (PIV) technology to analyze the airflow distribution between the medical staff and the patient. In the experiment, a simple version of the respirator was established to reproduce the breathing of human lungs. This model used oil to create smoke as a tracer aerosol, then a high-sensitivity camera was used to record the scattering light from this smoke (which is irradiated by the green laser sheet). Ultimately, after applying post-processing techniques, the airflow distribution is analyzed. PAO aerosol is the primary aerosol source in this experiment, and it is used to quantify the patient’s breathing; the concentration of PAO aerosol was measured at three different points: head, trunk, and feet. In addition, flow field visualization can effectively present the flow field distribution of the entire operating room; also, the results can be mutually verified with the PAO concentration measurement results. Aerosol concentrations were measured for six different oxygen supply devices with various tidal volumes of the artificial respirator, and the results were ranked from high to low concentrations for different oxygen supply devices and their operational oxygen supply flowrates: HFNC (70 l/min) > CPAP (40 l/min) > HFNC (30 l/min) > nasal cannula (15 l/min) > NRM (15 l/min) > VAPOX (28 l/min).

Non-RGB color filter options and traffic signal detection capabilities

Recently, non-RGB image sensors gain a traction in the automotive applications for high sensitivity camera system. Some color filter combinations have been proposed, such as RCCB, RCCG, RYYCy, etc. However, some of them have a difficulty to differentiate Yellow and Red traffic signals. This paper proposes the solution to that issue by shifting Red color filter edge. The differentiation performance was verified by the segmentation in the color space using the traffic signal spectrum database we built up. This result was also checked with image data by using a hyperspectral camera simulation. For the SNR comparison between those color filter options, we propose SNR10-based scheme for an apple-to-apple comparison and discuss on the overall pros / cons.

Reduction of saliva-derived droplet diffusion by mouth-closed tooth brushing in the era of COVID-19.

To clarify the effect of mouth-closed tooth brushing on the suppression of droplet generation in comparison with ordinary (mouth-open) tooth brushing and to investigate the difference in plaque removal efficacy between mouth-open and mouth-closed tooth brushing. Fourteen adults participated in the study. The labial/buccal, lingual, and occlusal surfaces of each sextant were brushed with the mouth open and closed, and a high-sensitivity camera and a high-power light source were used to measure the number of generated droplets. The plaque removal efficacy of each type of tooth brushing was evaluated according to the O'Leary Plaque Control Record. Significantly more droplets were generated by mouth-open brushing than by mouth-closed brushing. The number of droplets was highest when the lingual surfaces of the upper anterior sextants were brushed with the mouth open. In mouth-closed brushing, almost no droplets were observed from any region. The plaque removal rate with each type of brushing did not differ significantly among any regions except the lingual surfaces of the upper left sextant. Mouth-closed tooth brushing almost completely suppressed droplet generation and did not reduce the plaque removal efficacy. Therefore, mouth-closed tooth brushing is beneficial as an oral hygiene method during coronavirus disease 2019 outbreaks.

Real time, in-line optical mapping of single molecules of DNA

DNA optical mapping in nanochannels allows studying intact molecules and analyzing their long-range structure at the single-molecule level. Recent efforts have demonstrated that optical mapping can be used for various biomedical applications, such as bacteria identification, analysis of tumor cells, or whole-genome mapping. However, techniques for optical mapping are still slow and restricted to specialized labs. Here, we show a complete methodology for real-time DNA optical mapping on-chip, which is simple and offers high throughput. It does not require a microscope nor a high sensitivity camera to read the barcode, nor the use of external forces (like electrophoresis) to drive the molecules into the nanochannels. The DNA molecules are labelled with different methods, which allows barcoding known and unknown molecules. The barcoded DNA sample is analyzed in single-use, plastic nanoimprinted fluidic devices, which are versatile platforms to manipulate and stretch the molecules in nanochannels. And the fluorescent signal of the molecules is recorded in-line, in real time, with a laser system and a photon counter. With this methodology, we obtained barcodes of molecules with periodic sequences, where we marked one site per period. Furthermore, we barcoded the DNA of bacteriophages (Lambda and T4) and of a tumor virus (the Kaposi Sarcoma Herpesvirus, KSHV) by competitive binding, and obtained their unique fingerprints. Interestingly, this method succeeds in the correct detection (length and number) of highly repetitive structures such as the terminal repeat region of KSHV. These results show the versatility of the proposed methodology for fast (few milliseconds per molecule), low cost, high throughput (tens of molecules per minute) DNA analysis on-demand for biomedical applications. In particular, it can be used to analyze DNA with repeated sequences complementing other commercial techniques.

Dispersion of Aerosols Generated during Dental Therapy.

The novel coronavirus pandemic has resulted in an urgent need to study the risk of infection from aerosols generated during dental care and to conduct a review of infection controls. However, existing studies on aerosol particles related to dental treatment have mainly evaluated only the scattering range. Few studies have been conducted on the specifics of the generation of aerosol particles in clinical settings, their mechanisms and patterns of distribution throughout open or enclosed spaces, the duration that they remain suspended in air, and the amount and size of particles present. To minimize the influence of background particles, laser lights, a high-sensitivity camera, and particle counters were used in a large super clean laboratory to investigate the dynamics of aerosols generated during the operation of dental micromotors. The results indicate that aerosols tend to scatter upward immediately after generation and then gradually disperse into the surroundings. Most of the particles are less than 5 µm in size (only a few are larger), and all particles are widely distributed over the long term. Our research clearly elucidates that aerosols produced in dental care are distributed over a wide area and remain suspended for a considerable time in dental clinics before settling.

A Bio-Fluorometric Acetone Gas Imaging System for the Dynamic Analysis of Lipid Metabolism in Human Breath

We constructed an imaging system to measure the concentration of acetone gas by acetone reduction using secondary alcohol dehydrogenase (S-ADH). Reduced nicotinamide adenine dinucleotide (NADH) was used as an electron donor, and acetone was imaged by fluorescence detection of the decrease in the autofluorescence of NADH. In this system, S-ADH–immobilized membranes wetted with buffer solution containing NADH were placed in a dark box, and UV-LED excitation sheets and a high-sensitivity camera were installed on both sides of the optical axis to enable loading of acetone gas. A hydrophilic polytetrafluoroethylene (H-PTFE) membrane with low autofluorescence was used as a substrate, and honeycomb-like through-hole structures were fabricated using a CO2 laser device. After loading the enzyme membrane with acetone gas standards, a decrease in fluorescence intensity was observed in accordance with the concentration of acetone gas. The degree of decrease in fluorescence intensity was calculated using image analysis software; it was possible to quantify acetone gas at concentrations of 50–2000 ppb, a range that includes the exhaled breath concentration of acetone in healthy subjects. We applied this imaging system to measure the acetone gas in the air exhaled by a healthy individual during fasting.

Photogrammetric Digital Surface Model Reconstruction in Extreme Low-Light Environments

Digital surface models (DSM) have become one of the main sources of geometrical information for a broad range of applications. Image-based systems typically rely on passive sensors which can represent a strong limitation in several survey activities (e.g., night-time monitoring, underground survey and night surveillance). However, recent progresses in sensor technology allow very high sensitivity which drastically improves low-light image quality by applying innovative noise reduction techniques. This work focuses on the performances of night-time photogrammetric systems devoted to the monitoring of rock slopes. The study investigates the application of different camera settings and their reliability to produce accurate DSM. A total of 672 stereo-pairs acquired with high-sensitivity cameras (Nikon D800 and D810) at three different testing sites were considered. The dataset includes different camera configurations (ISO speed, shutter speed, aperture and image under-/over-exposure). The use of image quality assessment (IQA) methods to evaluate the quality of the images prior to the 3D reconstruction is investigated. The results show that modern high-sensitivity cameras allow the reconstruction of accurate DSM in an extreme low-light environment and, exploiting the correct camera setup, achieving comparable results to daylight acquisitions. This makes imaging sensors extremely versatile for monitoring applications at generally low costs.

Sodium variation in Geminid meteoroids from (3200) Phaethon

Sodium is a perfect indicator to investigate the volatility within meteoroid composition. Spectroscopic observations of the Geminid meteors were carried out using modern high sensitive large format CMOS cameras. 149 visible spectra of the Geminid meteors observed in 2017 and 2018 were analyzed by a newly developed procedure. The variation of Na, Mg and Fe during meteor ablation in the atmosphere has been studied. Although sodium is depleted in ~80% of the Geminids, statistically significant variations of sodium in the Geminid meteors were found. It should be noted that Na depletion in the Geminid meteors increased with decreasing meteoroid size. A yearly variation of Na in the Geminid meteor streams was also found. Solar-heating age across the different parts of the meteoroids stream ejected from a parent active asteroid (3200) Phaethon having 0.14 AU small perihelion distance seems to the most likely explanation for the sodium variation and depletion. Surprisingly, three iron Geminid meteors were detected across the maximum of 2018 Geminids.