Near-infrared Camera Research Articles

Multiple stellar populations in globular clusters with JWST: an NIRCam view of 47 Tucanae

ABSTRACT We use images collected with the near-infrared camera (NIRCam) onboard the JWST and with the Hubble Space Telescope (HST) to investigate multiple populations at the bottom of the main sequence (MS) of 47 Tucanae. The mF115W versus mF115W − mF322W2 colour–magnitude diagram (CMD) from NIRCam shows that, below the knee, the MS stars span a wide colour range, where the majority of M-dwarfs exhibit blue colours, and a tail of stars are distributed towards the red. A similar pattern is observed from the mF160W versus mF110W − mF160W CMD from HST, and multiple populations of M-dwarfs are also visible in the optical mF606W versus mF606W − mF814W CMD. The NIRCam CMD shows a narrow sequence of faint MS stars with masses smaller than $0.1\, \mathcal {M}_{\odot }$. We introduce a chromosome map of M-dwarfs that reveals an extended first population and three main groups of second-population stars. By combining isochrones and synthetic spectra with appropriate chemical composition, we simulate colours and magnitudes of different stellar populations in the NIRCam filters (at metallicities [Fe/H] = −1.5 and [Fe/H] = −0.75) and identify the photometric bands that provide the most efficient diagrams to investigate the multiple populations in globular clusters. Models are compared with the observed CMDs of 47 Tucanae to constrain M-dwarfs’ chemical composition. Our analysis suggests that the oxygen range needed to reproduce the colours of first- and second-population M-dwarfs is similar to that inferred from spectroscopy of red giants, constraining the proposal that the chemical variations are due to mass transfer phenomena in proto-clusters.

Coaxial and synchronous monitoring of molten pool height, area, and temperature in laser metal deposition

Laser Metal Deposition is an additive manufacturing technology that enables to realize of one-of-a-kind large components with a free-form geometry. However, the advantages of laser metal deposition from the economic and sustainability points of view can be attenuated by the presence of defects in the realized components. The process should be real-time monitored to immediately identify the onset of defects or process drifts that may undermine the outcome of the build, also enabling the possibility to immediately act against them with feedback control. Many of the proposed solutions in monitoring the Laser Metal Deposition process exploit the use of only one sensor or more but decoupled ones, which does not provide a comprehensive overview of the process. In this work, a coaxial multi-sensor monitoring system is proposed and exploited to capture the variation of three different process signatures. A custom laser triangulator, a near-infrared camera and a ratio pyrometer for simultaneous monitoring of the molten pool height, molten pool area, and molten pool temperature, respectively, are coaxially integrated. Thanks to the possibility to extract concurrent (in spatial and time domains) signals directly from the workpiece area and in real-time, a comprehensive status of the deposition can be deduced. The influence of the process parameters on the sensed outputs is investigated, and the relationships between the process signatures can be researched. While the molten pool area and its temperature are mostly affected by the laser power, the scan speed is more impactful on the molten pool height. A good linear correlation between the molten pool temperature and the area is assessed, while no correlation with the molten pool height is found, making it almost independently manipulatable.

Identification and properties of intense star-forming galaxies at redshifts z > 10

Surveys with James Webb Space Telescope (JWST) have discovered candidate galaxies in the first 400 Myr of cosmic time. Preliminary indications have suggested these candidate galaxies may be more massive and abundant than previously thought. However, without confirmed distances, their inferred properties remain uncertain. Here we identify four galaxies located in the JWST Advanced Deep Extragalactic Survey (JADES) Near-Infrared Camera (NIRCam) imaging with photometric redshifts z~10-13. These galaxies include the first redshift z>12 systems discovered with distances spectroscopically confirmed by JWST in a companion paper. Using stellar population modelling, we find the galaxies typically contain a hundred million solar masses in stars, in stellar populations that are less than one hundred million years old. The moderate star formation rates and compact sizes suggest elevated star formation rate surface densities, a key indicator of their formation pathways. Taken together, these measurements show that the first galaxies contributing to cosmic reionisation formed rapidly and with intense internal radiation fields.

Diagnostic accuracy of combined optical- and radio-guided SNB for neck staging of oral squamous cell carcinoma lesions in the anterior oral cavity

PurposeThe purpose was to investigate the diagnostic performance of bimodal optical and radio-guided sentinel node biopsy (SNB) for oral squamous cell carcinoma (OSCC) sub-sites in the anterior oral cavity.MethodsProspective study of 50 consecutive patients with cN0 OSCC scheduled for SNB was injected with the tracer complex Tc99m:ICG:Nacocoll. A near-infrared camera was applied for optical SN detection. Endpoints were modality for intraoperative SN detection and false omission rate at follow-up.ResultsIn all patients, a SN could be detected. In 12/50 (24%) of cases, the SPECT/CT showed no focus in level 1, but intraoperatively a SN in level 1 was optically detected. In 22/50 cases (44%), an additional SN was identified only due to the optical imaging. At follow-up, the false omission rate was 0%.ConclusionOptical imaging appears to be an effective tool to allow real-time SN identification comprising level 1 unaffected by possible interference of radiation site from the injection.

The SOUL view of IRAS 20126+4104

Context. We exploit the increased sensitivity of the recently installed adaptive optics SOUL at the LBT to obtain new high-spatial-resolution near-infrared images of the massive young stellar object IRAS20126+4104 and its outflow. Aims. We aim to derive the jet proper motions and kinematics, as well as to study its photometric variability by combining the novel performances of SOUL together with previous near-infrared images. Methods. We used both broad-band (Ks, K′) and narrow-band (Brγ, H2) observations from a number of near-infrared cameras (UKIRT/UFTI, SUBARU/CIAO, TNG/NICS, LBT/PISCES, and LBT/LUCI1) to derive maps of the continuum and the H2 emission in the 2.12 µm line. Three sets of images, obtained with adaptive optics (AO) systems (CIAO, in 2003; FLAO, in 2012; SOUL, in 2020), allowed us to derive the proper motions of a large number of H2 knots along the jet. Photometry from all images was used to study the jet variability. Results. We derived knot proper motions in the range of 1.7–20.3 mas yr−1 (i.e. 13–158 km s−1 at 1.64 kpc), implying an average outflow tangential velocity of ~80 km s−1. The derived knot dynamical age spans a ~200–4000 yr interval. A ring-like H2 feature near the protostar location exhibits peculiar kinematics and may represent the outcome of a wide-angle wind impinging on the outflow cavity. Both H2 geometry and velocities agree with those inferred from proper motions of the H2O masers, located at a smaller distance from the protostar. Although the total H2 line emission from the knots does not exhibit time variations at a ⪞0.3 mag level, we have found a clear continuum flux variation (radiation scattered by the dust in the cavity opened by the jet) which is anti-correlated between the blue-shifted and red-shifted lobes and may be periodic (with a period of ~12–18 yr). We suggest that the continuum variability might be related to inner-disc oscillations which have also caused the jet precession. Conclusions. Our analysis shows that multi-epoch high-spatial-resolution imaging in the near-infrared is a powerful tool to unveil the physical properties of highly embedded massive protostars.

Expectations of the Size Evolution of Massive Galaxies at 3 ≤ z ≤ 6 from the TNG50 Simulation: The CEERS/JWST View

We present a catalog of about 25,000 images of massive (M ⋆ ≥ 109 M ⊙) galaxies at redshifts 3 ≤ z ≤ 6 from the TNG50 cosmological simulation, tailored for observations at multiple wavelengths carried out with JWST. The synthetic images were created with the SKIRT radiative transfer code, including the effects of dust attenuation and scattering. The noiseless images were processed with the mirage simulator to mimic the Near Infrared Camera (NIRCam) observational strategy (e.g., noise, dithering pattern, etc.) of the Cosmic Evolution Early Release Science (CEERS) survey. In this paper, we analyse the predictions of the TNG50 simulation for the size evolution of galaxies at 3 ≤ z ≤ 6 and the expectations for CEERS to probe that evolution. In particular, we investigate how sizes depend on the wavelength, redshift, mass, and angular resolution of the images. We find that the effective radius accurately describes the three-dimensional half-mass–radius of the TNG50 galaxies. Sizes observed at 2 μm are consistent with those measured at 3.56 μm at all redshifts and masses. At all masses, the population of higher-z galaxies is more compact than their lower-z counterparts. However, the intrinsic sizes are smaller than the mock observed sizes for the most massive galaxies, especially at z ≲ 4. This discrepancy between the mass and light distributions may point to a transition in the galaxy morphology at z = 4–5, where massive compact systems start to develop more extended stellar structures. 22 22 Data publicly released at https://www.tng-project.org/costantin22.

Evaluating clinical near-infrared surgical camera systems with a view to optimizing operator and computational signal analysis.

As clinical evidence on the colorectal application of indocyanine green (ICG) perfusion angiography accrues, there is also interest in computerizing decision support. However, user interpretation and software development may be impacted by system factors affecting the displayed near-infrared (NIR) signal. We aim to assess the impact of camera positioning on the displayed NIR signal across different open and laparoscopic camera systems. The effects of distance, movement, and target location (center versus periphery) on the displayed fluorescence signal of different systems were measured under electromagnetic stereotactic guidance from an ICG-albumin model and in vivo during surgery. Systems displayed distinct fluorescence performances with variance apparent with scope optical lens configuration (0deg versus 30deg), movement, target positioning, and distance. Laparoscopic system readings fitted inverse square function distance-intensity curves with one device and demonstrated a direction dependent sigmoid curve. Laparoscopic cameras presented central targets as brighter than peripheral ones, and laparoscopes with angled optical lens configurations had a diminished field of view. One handheld open system also showed a distance-intensity relationship, whereas the other maintained a consistent signal despite distance, but both presented peripheral targets brighter than central ones. Optimal clinical use and signal computational development requires detailed appreciation of system behaviors.

Persistent foramen of Huschke: Clinical manifestations and complications, systematic review

BackgroundForamen of Huschke is a bone defect with wide clinical symptoms which ca can be responsible for severe complications. Clinical history and imaging are unspecific, it is therefore essential to recognize and treat the pathology related to the persistence of this foramen, to avoid destruction of the TMJ, chronic pain or ObjectiveThe aim of this review was to summarise the clinical manifestations and complications of persistent foramen of Huschke in adult patients, through a review of the cases reported in the literature. Methods & materialsA literature search of the PubMed, Cochrane Library, ScienceDirect and Embase databases was conducted for all articles published up to November 2022 to identify studies and case reports concerning clinical manifestations and complications of persistent foramen of Huschke in adult patients, with the key words “foramen of Huschke” or “foramen tympanicum”. Results74 papers where firstly identify, and 21 were selected. This correspond to 46 patients with the additional case from our department. Symptoms mostly reported consisted of otitis (63%, 29/46), otorrhea (28.26%, 13/46), and masticatory tinnitus (19.57%, 9/46). Diagnosis was priority made by CT-scan (95.65%, 44/46). Surgery was the most performed treatment (28.26%, 13/46). In our case, the use of FLUOBEAM® NIR camera was help-full for TMJ surgery. ConclusionPersistent foramen of Huschke should be suspected in the presence of otitis, otorrhea and masticatory tinnitus. Knowledge of this anatomical variation could help to treat certain pathology like TMJ disorders or TMJ septic arthritis.

Rapid shipboard measurement of net-collected marine microplastic polymer types using near-infrared hyperspectral imaging

Isolation and detection of microplastics (MP) in marine samples is extremely cost- and labor-intensive, limiting the speed and amount of data that can be collected. In the current work, we describe rapid measurement of net-collected MPs (net mesh size 300 µm) using a benchtop near-infrared hyperspectral imaging system during a research expedition to the subtropical North Atlantic gyre. Suspected plastic particles were identified microscopically and mounted on a black adhesive background. Particles were imaged with a Specim FX17 near-infrared linescan camera and a motorized stage. A particle mapping procedure was built on existing edge-finding algorithms and a polymer identification method developed using spectra from virgin polymer reference materials. This preliminary work focused on polyethylene, polypropylene, and polystyrene as they are less dense than seawater and therefore likely to be found floating in the open ocean. A total of 27 net tows sampled 2534 suspected MP particles that were imaged and analyzed at sea. Approximately 77.1% of particles were identified as polyethylene, followed by polypropylene (9.2%). A small fraction of polystyrene was detected only at one station. Approximately 13.6% of particles were either other plastic polymers or were natural materials visually misidentified as plastics. Particle size distributions for PE and PP particles with a length greater than 1 mm followed an approximate power law relationship with abundance. This method allowed at-sea, near real-time identification of MP polymer types and particle dimensions, and shows great promise for rapid field measurements of microplastics in net-collected samples.

Understanding fluorescence time curves during ileal pouch-anal anastomosis with or without vascular ligation

BackgroundIntraoperative indocyanine green fluorescence angiography (ICG-FA) may be of added value during pouch surgery, in particular after vascular ligations as lengthening maneuver. The aim was to determine quantitative perfusion parameters within the efferent/afferent loop and explore the impact of vascular ligation. Perfusion parameters were also compared in patients with and without anastomotic leakage (AL).MethodsAll consenting patients that underwent FA-guided ileal pouch-anal anastomosis (IPAA) between July 2020 and December 2021 were included. After intravenous bolus injection of 0.1 mg/kg ICG, the near-infrared camera (Stryker Aim 1688) registered the fluorescence intensity over time. Quantitative analysis of ICG-FA from standardized regions of interests on the pouch was performed using software. Fluorescence parameters were extracted for inflow (T0, Tmax, Fmax, slope, Time-to-peak) and outflow (T90% and T80%). Change of management related to FA findings and AL rates were recorded.ResultsTwenty-one patients were included, three patients (14%) required vascular ligation to obtain additional length, by ligating terminal ileal branches in two and the ileocolic artery (ICA) in one patient. In nine patients the ICA was already ligated during subtotal colectomy. ICG-FA triggered a change of management in 19% of patients (n = 4/21), all of them had impaired vascular supply (ligated ileocolic/ terminal ileal branches). Overall, patients with intact vascular supply had similar perfusion patterns for the afferent and efferent loop. Pouches with ICA ligation had longer Tmax in both afferent as efferent loop than pouches with intact ICA (afferent 51 and efferent 53 versus 41 and 43 s respectively). Mean slope of the efferent loop diminished in ICA ligated patients 1.5(IQR 0.8–4.4) versus 2.2 (1.3–3.6) in ICA intact patients.ConclusionQuantitative analysis of ICG-FA perfusion during IPAA is feasible and reflects the ligation of the supplying vessels.

Photoluminescence detection method for silicon photovoltaic modules at high light level

The defect of silicon photovoltaic (PV) modules excited by photoluminescence (PL) technology at high light level (HLL) will be easily drowned in the ambient light; therefore, the detection equipment cannot sense the defect information directly. To solve this problem, a defect detection method that effectively resists the interference of ambient light in daytime is proposed in this paper. This method uses modulated light as the excitation for PV modules, and employs the near-infrared (NIR) camera to capture a group of image sequences satisfying the modulation characteristics. To restore the defect information of PV modules from image sequences, an algorithm based on time domain error is proposed. Finally, hardware acceleration of algorithm by field programmable gate array is implemented to solve the problem of time-consuming tasks for the personal computer. The experimental results show that this method can effectively restore the defect pattern with HLL extending from 0.1 lx to 11,170 ± 5 lx. Therefore, this work can provide an effective detection strategy for PL detection of PV modules at HLL.

Left basilar VATS segmentectomy for intra lobar pulmonary sequestration using indocyanine green for identification of the intersegmental plane: a case report

: Pulmonary sequestration is a rare congenital abnormality that requires surgical resection if symptomatic. The pulmonary sequestration can be extra lobar with a separate visceral pleura, artery and venous drainage or intra lobar contained within the visceral pleura of the lung with a separate artery and venous drainage to the pulmonary vein. Rarely the entire lobe is affected in intra lobar sequestration and segmentectomy should be considered rather than lobectomy. A case of an intra lobar sequestration in the left lower lobe with a feeding artery coming from the descending thoracic aorta is presented. The patient was a young woman, who had experienced recurrent pneumonia for one year. A left video-assisted thoracoscopic surgery (VATS) basilar segmentectomy was performed using a standardized anterior three-port approach. Due to the recurrent infections, the hilar lymph nodes were fibrotic, and dissection was performed using an advanced energy system. Identification of the intersegmental plane may be challenging in segmentectomies. Most surgeons use an inflation-deflation technique. In this case identification was performed using a near-infra red camera and intravenous injection of indocyanine green. Identification was successful. The postoperative course was uneventful with a length of stay of two days. On follow up 6 months postoperatively, the patient was without any symptoms.

Extending the extinction law in 30 Doradus to the infrared with JWST

We measured the extinction law in the 30 Dor star formation region in the Large Magellanic Cloud using Early Release Observations (EROs) taken with Near-Infrared Camera (NIRCam) on board the JWST, thereby extending previous studies carried out with the Hubble Space Telescope to the infrared. We used red clump stars to derive the direction of the reddening vector in twelve bands and we present the extinction law in this massive star forming region from 0.3 to 4.7 μm. At wavelengths longer than 1 μm, we find a ratio of total and selective extinction twice as high as in the diffuse Milky Way interstellar medium and a change in the relative slope from the optical to the infrared domain. Additionally, we derive an infrared extinction map and find that extinction closely follows the structure of the highly embedded regions of 30 Dor.

Handheld Autofluorescence Imaging System for Intraoperative Parathyroid Detection.

Hypoparathyroidism and hypocalcemia are common complications after thyroid surgery. Parathyroids may be incidentally damaged or removed because they are difficult to distinguish from surrounding tissue. Intraoperative optical technologies such as near infrared autofluorescence (NIRAF) are becoming increasingly popular to help identify parathyroids during thyroid surgery. The objective of this video is to introduce a developing NIRAF device called hANDY-i and compare the device with existing Food and Drug Administration approved technology. hANDY-i is developed by Optosurgical, LLC. The device consists of a coaxial 785 nm laser excitation module and coregistred red-green-blue and near-infrared cameras. Operation of the device and output from preliminary intraoperative use are shown. hANDY-i performs well, producing intuitive side-by-side NIRAF and RGB images of the operating field. The device demonstrates high contrast between suspected parathyroid glands and surrounding tissue. Operating theater, overhead lamps, and surgical headlights can all be used with the device. The device is also shown to be effective in both in vivo and ex vivo applications. The prototype described advance NIRAF technology by reducing light sensitivity and improving output representation. In doing so, hANDY-i makes NIRAF more accessible and less obstructive to the surgical workflow. This study was supported by the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health under Award Number R43EB030874. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.Yoseph Kim is an employee of Optosurgical LLC. Jaepyeong Cha has ownership stake in Optosurgical LLC. For all other authors, no competing financial interests exist.Runtime of video: 7 mins 14 secs.

CEERS Key Paper. II. A First Look at the Resolved Host Properties of AGN at 3 < z < 5 with JWST

We report on the host properties of five X-ray-luminous active galactic nuclei (AGN) identified at 3 < z < 5 in the first epoch of imaging from the Cosmic Evolution Early Release Science Survey. Each galaxy has been imaged with the JWST Near-Infrared Camera, which provides rest-frame optical morphologies at these redshifts. We also derive stellar masses and star formation rates for each host by fitting its spectral energy distribution using a combination of galaxy and AGN templates. We find that three of the AGN hosts have spheroidal morphologies, one is a bulge-dominated disk, and one is dominated by pointlike emission. None are found to show strong morphological disturbances that might indicate a recent interaction or merger event. When compared to a sample of mass-matched inactive galaxies, we find that the AGN hosts have morphologies that are less disturbed and more bulge-dominated. Notably, all four of the resolved hosts have rest-frame optical colors consistent with a quenched or poststarburst stellar population. The presence of AGN in passively evolving galaxies at z > 3 is significant because a rapid feedback mechanism is required in most semianalytic models and cosmological simulations to explain the growing population of massive quiescent galaxies observed at these redshifts. Our findings show that AGN can continue to inject energy into these systems after their star formation is curtailed, potentially heating their halos and preventing renewed star formation. Additional observations will be needed to determine what role this feedback may play in helping to quench these systems and/or maintain their quiescent state.

Infrared polarisation study of Lynds 1340: A case of RNO 8

This paper describes the polarisation study of a Lynds cloud, LDN 1340, $$\alpha = 2$$ h32m and $$\delta = 73^{\circ } 00^\prime $$ corresponding to galactic coordinates of $$\ell = 130^{\circ }.07$$ and $$b=$$ 11 $$^{\circ }.6$$ , with emphasis on the RNO 8 area. The cloud has been observed using the 1.2 m telescope at Mt. Abu Infrared Observatory, in the infrared wavelength band using the Near-Infrared Camera, Spectrograph and Polarimeter instrument. The polarimetric observations were used to map the magnetic field geometry around the region. We combined our measurements with archival data from the 2MASS and WISE surveys. The Gaia EDR3 and DR3 data for the same region were used for distance, proper motion, and other astrophysical information. The analysis of the data reveals areas with ordered polarisation vectors in the region of RNO 8. The position angle measurements reveal polarisation due to dichroic extinction which is consistent with the Galactic magnetic field. The magnetic field strength was calculated for the RNO 8 region using the Chandrashekhar–Fermi method and the value estimated is $$\sim $$ 42 $$\mu $$ G.

Optimization of a Microwave Polarimeter for Astronomy with Optical Correlation and Detection

Cosmic Microwave Background (CMB) B-modes detection is the main focus of future CMB experiments because of the valuable information it contains, particularly to probe the physics of the very early universe. For this reason, we have developed an optimized polarimeter demonstrator sensitive to the 10-20 GHz band in which the signal received by each antenna is modulated into a Near Infrared (NIR) laser by a Mach-Zehnder modulator. Then, these modulated signals are optically correlated and detected using photonic back-end modules consisting of voltage-controlled phase shifters, a 90-degree optical hybrid, a pair of lenses, and an NIR camera. During laboratory tests, a 1/f-like noise signal related to the low phase stability of the demonstrator has been found experimentally. To solve this issue, we have developed a calibration method that allows us to remove this noise in an actual experiment, until obtaining the required accuracy level in the measurement of polarization.

The JWST Resolved Stellar Populations Early Release Science Program. III. Photometric Star–Galaxy Separations for NIRCam

We present criteria for separately classifying stars and unresolved background galaxies in photometric catalogs generated with the point-spread function fitting photometry software DOLPHOT from images taken of Draco II, WLM, and M92 with the Near Infrared Camera (NIRCam) on JWST. Photometric quality metrics from DOLPHOT in one or two filters can recover a pure sample of stars. Conversely, colors formed between short-wavelength and long-wavelength filters can be used to effectively identify pure samples of galaxies. Our results highlight that the existing DOLPHOT output parameters can be used to reliably classify stars in our NIRCam data without the need to resort to external tools or more complex heuristics.

Design of Low-Complexity Convolutional Neural Network Accelerator for Finger Vein Identification System.

In the biometric field, vein identification is a vital process that is constrained by the invisibility of veins as well as other unique features. Moreover, users generally do not wish to have their personal information uploaded to the cloud, so edge computing has become popular for the sake of protecting user privacy. In this paper, we propose a low-complexity and lightweight convolutional neural network (CNN) and we design intellectual property (IP) for shortening the inference time in finger vein recognition. This neural network system can operate independently in client mode. After fetching the user's finger vein image via a near-infrared (NIR) camera mounted on an embedded system, vein features can be efficiently extracted by vein curving algorithms and user identification can be completed quickly. Better image quality and higher recognition accuracy can be obtained by combining several preprocessing techniques and the modified CNN. Experimental data were collected by the finger vein image capture equipment developed in our laboratory based on the specifications of similar products currently on the market. Extensive experiments demonstrated the practicality and robustness of the proposed finger vein identification system.

Microelectromechanical Microsystems-Supported Photothermal Immunoassay for Point-of-Care Testing of Aflatoxin B1 in Foodstuff.

Accurate identification of acutely toxic and low-fatality mycotoxins on a large scale in a quick and cheap manner is critical for reducing population mortality. Herein, a portable photothermal immunosensing platform supported by a microelectromechanical microsystem (MEMS) without enzyme involvement was reported for point-of-care testing of mycotoxins (in the case of aflatoxin B1, AFB1) in food based on the precise satellite structure of Au nanoparticles. The synthesized Au nanoparticles with a well-defined, graded satellite structure exhibited a significantly enhanced photothermal response and were coupled by AFB1 antibodies to form signal conversion probes by physisorption for further target-promoted competitive responses in microplates. In addition, a coin-sized miniature NIR camera device was constructed for temperature acquisition during target testing based on advanced MEMS fabrication technology to address the limitation of expensive signal acquisition components of current photothermal sensors. The proposed MEMS readout-based microphotothermal test method provides excellent AFB1 response in the range of 0.5-500 ng g-1 with detection limits as low as 0.27 ng g-1. In addition, the main reasons for the efficient photothermal transduction efficiency of Au with different graded structures were analyzed by finite element simulations, providing theoretical guidance for the development of new Au-based photothermal agents. In conclusion, the proposed portable micro-photothermal test system offers great potential for point-of-care diagnostics for residents, which will continue to facilitate immediate food safety identification in resource-limited regions.