Metal-Organic Framework-Based Surface-Enhanced Raman Scattering Sensing Platform for Trace Malondialdehyde Detection in Tears.

Disease biomarkers in tears are crucial for clinical diagnosis and health monitoring. However, the limited volume of tear samples, low concentration of tear biomarkers, and complex tear composition present challenges for precise testing. We introduce a spot-on testing platform of metal-organic framework (MOF)-based surface-enhanced Raman scattering (SERS) capillary column, which is capable of target molecules selective separation and enrichment for tear biomarkers in situ detection. It consists of Au nanostars for effective SERS signal and a porous MOF shell for separating impurities through molecular sieving effect. This platform allows for simultaneous collection and detection of tear, capturing the disease biomarker malondialdehyde in tears with a 9.38 × 10-9 mol/L limit of detection. Moreover, we designed a hand-held device based on this tubular SERS sensor, successfully diagnosing patients with dry eye disease. This functional capillary column enables noninvasive and rapid diagnosis of biomarkers in biofluids, providing potential for disease diagnosis and healthcare monitoring.

Microwave coupled Zeeman splitting spectroscopy of a cesium nPJ Rydberg atom.

We perform measurements of microwave spectra of cesium Rydberg 51S1/2 → 51PJ transitions with the linewidth approaching the Fourier limit. A two-photon scheme excites the ground-state atoms to the Rydberg 51S1/2 state, and a weak microwave photon couples the Rydberg transition of 51S1/2 → 51PJ. The hyperfine structure of 51P1/2 can be clearly resolved with a narrow linewidth microwave spectra by using the method of ion detection. Furthermore, we investigate the Zeeman effect of the 51P1/2,3/2 state. The theoretical calculations reproduce the measurement well. Our experimental measurements provide a reliable technical solution for the investigation of high angular momentum Rydberg states, which is conducive to further realizing the coherent manipulation of Rydberg energy levels and improving the sensitivity of electromagnetic field measurement.

Mechanism of tumor-derived extracellular vesicles in prostatic cancer progression through the circFMN2/KLF2/RNF128 axis.

Circular RNAs (circRNAs) are a major type of cargos encapsulated in extracellular vesicles (EVs) and regulate the progression of prostatic cancer (PC). This study was conducted to explore the role of tumor-derived EVs in PC cell proliferation, invasion, and migration via shuttle of circRNA formin 2 (circFMN2). RT-qPCR or Western blot assay showed that circFMN2 was upregulated while KLF2 and RNF128 were downregulated in PC tissues and cells. EVs were separated from PC cells and characterized and its internalization in PC cells was examined, which suggested that PC-EVs mediated the shuttle of circFMN2 to upregulate circFMN2 expression in PC cells. PC cell functions were determined by cell counting kit-8, colony formation and Transwell assays, which suggested that PC-EVs fueled the proliferation, invasion, and migration of PC cells. At cellular level, PC-EVs mediated the shuttle of circFMN2 to upregulate circFMN2 expression in PC cells, and circFMN2 binding to HuR decreased the HuR-KLF2 interaction and repressed KLF2 expression, which further reduced the KLF2-RNF128 promoter binding and repressed RNF128 transcription. Overexpression of KLF2/RNF128 ablated the effects of PC-EVs on the proliferation, invasion, and migration of PC cells. The xenograft tumor models and lung/liver metastasis models were established and revealed that PC-EVs accelerated tumorigenesis and metastasis in vivo via delivery of circFMN2 and repression of KLF2/RNF128.

Robust Ramsey interferometer based on a single Rydberg polariton.

We demonstrate a robust single-photon Ramsey interferometer based on a single Rydberg excitation, where the photon is stored as a Rydberg polariton in an ensemble of atoms. This coherent conversion of the photon to Rydberg polariton enables to split an incoming photon into a superposition state of two Rydberg states by applying microwave fields, which constructs two paths of interferometer. Ramsey interference fringes are demonstrated when we scan either the detuning of the microwave or the free evolution time, from which we can obtain the resonant transition frequency of two Rydberg states. We use the Ramsey-like sequence to demonstrate coherent manipulation of the stored single-photon to construct different interference patterns. In addition, the robustness of the Ramsey interferometer to the fluctuation of incoming photon numbers and optical depth (OD) of the atomic ensemble is tested, showing that the coherent of Ramsey interferometer is preserved for input photon number in a range of Rin < 15 and for OD varying from 1.0 to 4.0. The robust interferometer will find its applications in quantum precision measurement.

Dephasing of ultracold cesium 80D5/2-Rydberg electromagnetically induced transparency.

We study Rydberg electromagnetically induced transparency (EIT) of a cascade three-level atom involving 80D5/2 state in a strong interaction regime employing a cesium ultracold cloud. In our experiment, a strong coupling laser couples 6P3/2 to 80D5/2 transition, while a weak probe, driving 6S1/2 to 6P3/2 transition, probes the coupling induced EIT signal. At the two-photon resonance, we observe that the EIT transmission decreases slowly with time, which is a signature of interaction induced metastability. The dephasing rate γOD is extracted with optical depth OD = γODt. We find that the optical depth linearly increases with time at onset for a fixed probe incident photon number Rin before saturation. The dephasing rate shows a nonlinear dependence on Rin. The dephasing mechanism is mainly attributed to the strong dipole-dipole interactions, which leads to state transfer from nD5/2 to other Rydberg states. We demonstrate that the typical transfer time τ0(80D) obtained by the state selective field ionization technique is comparable with the decay time of EIT transmission τ0(EIT). The presented experiment provides a useful tool for investigating the strong nonlinear optical effects and metastable state in Rydberg many-body systems.

Manipulation of single stored-photon with microwave field based on Rydberg polariton.

We demonstrate a coherent microwave manipulation of a single optical photon based on a single Rydberg excitation in an atomic ensemble. Due to the strong nonlinearities in a Rydberg blockade region, a single photon can be stored in the formation of Rydberg polariton using electromagnetically induced transparency (EIT). The manipulation of the stored single photon is performed by applying a microwave field that resonantly couples the nS1/2 and nP3/2, while the coherent readout is performed by mapping the excitation into a single photon. We achieve a single photon source with g(2)(0) = 0.29 ± 0.08 at 80S1/2 without applying microwave fields. By implementing the microwave field during the storage time and retrieval process, we show the Rabi oscillation and modulation of stored photons that can be controlled to retrieve early or late. Rapid modulation frequencies up to 50 MHz can be obtained. Our experimental observations can be well explained via numerical simulations based on an improved superatom model accounting for the dipole-dipole interactions in a Rydberg EIT medium. Our work provides a way to manipulate the stored photons by employing the microwave field, which is significant for developing quantum technologies.

Super low-frequency electric field measurement based on Rydberg atoms.

We demonstrate the measurement of super low-frequency electric field using Rydberg atoms in an atomic vapor cell with inside parallel electrodes, thus overcoming the low-frequency electric-field-screening effect at frequencies below a few kHz. Rydberg electromagnetically induced transparency (EIT) spectra involving 52D5/2 state is employed to measure the signal electric field. An auxiliary DC field is applied to improve the sensitivity. A DC Stark map is demonstrated, where the utilized 52D5/2 exhibits mj = 1/2, 3/2, 5/2 Stark shifts and splittings. The mj = 1/2 state is employed to detect the signal field because of its larger polarizability than that of mj = 3/2, 5/2. Also, we show that the strength of the spectrum is dependent on the angle between the laser polarizations and the electric field. With optimization of the applied DC field to shift the mj = 1/2 Rydberg energy level to a high sensitivity region and the laser polarizations to obtain the maximum mj = 1/2 signal, we achieve the detection of the signal electric field with a frequency of 100 Hz down to 214.8 µV/cm with a sensitivity of 67.9 µV cm-1Hz-1/2, and the linear dynamic range is over 37 dB. Our work extends the measurement frequency of Rydberg sensors to super low frequency with high sensitivity, which has the advantages of high sensitivity and miniaturization for receiving super low frequency.

Dissociation of ultracold cesium Rydberg-ground molecules.

We report the experimental measurements of the decay rate of polar cesium nD5/2 - 6S1/2 Rydberg-ground molecules with a large principal quantum number range of 35 ≤ n ≤ 40. Rydberg molecules are prepared employing the method of two-photon photoassociation and the molecular (atomic) ions, due to autoionization (blackbody photoionization), are detected with a microchannel plate detector. The decay rate Γ of the vibrational ground state of the deep and shadow bound molecules for triplet (TΣ) and mixed singlet-triplet (S,TΣ) are measured by fitting the molecular population with the exponential function. Comparing with the parent atom, the decay rate of the polar Rydberg-ground molecule shows an obvious increase with a magnitude of a few µs. The possible dissociation mechanism of polar Rydberg-ground molecules including a collisional decay, blackbody induced decay, and coupling of adjacent Rydberg states and tunneling decay are discussed in detail. The theoretical model is induced to simulate the measurements, showing agreement.

Relationship between severity of obstructive sleep apnea and benign prostatic hyperplasia.

PURPOSE: The cause of benign prostatic hyperplasia (BPH) is controversial, local hypoxia and inflammation being the main two possibilities proposed. The aim of this study was to evaluate the relationship between obstructive sleep apnea (OSA) and BPH. METHODS: The study cohort comprised men from January 2016 to December 2020 in our Sleep Center. These patients were classified into four groups (no, mild, moderate, severe OSA) by apnea-hypopnea indexes (AHI). Logistic regression was used to identify independent risk factors for BPH, after which participants were stratified into younger (age ≤ 40 years) and older groups (age > 40 years) for further analysis. RESULTS: The study cohort comprised 467 patients including 135 younger subjects and 332 older subjects. The prevalence of BPH in the above listed AHI categories was 37.5%, 55.0%, 62.9%, and 52.3%, respectively (p = 0.075). Logistic regression analysis of all patients identified age as a risk factor for BPH (p < 0.001). Stratified analysis according to AHI category found a prevalence of BPH of 0.0%, 13.0%, 33.3%, and 43.9%, respectively, in younger group (p = 0.006), and 52.2%, 71.9%, 71.1%, and 56.3%, respectively, in older group (p = 0.038). Logistic regression analysis found age and AHI were independent risk factors for BPH in younger group (both p < 0.05), whereas only age was identified as a risk factor for BPH in older group (p < 0.001). CONCLUSIONS: Age is an independent risk factor for BPH in men with OSA. AHI is also an independent risk factor for BPH in younger men, suggesting that OSA may affect development of BPH in younger men.

Self-reported sleep quality and oligo/astheno/teratozoospermia among men attending an infertility clinic: a longitudinal study.

OBJECTIVE: We aimed to examine the influence of sleep disturbances on the risk of oligo/astheno/teratozoospermia (OAT) in men attending an infertility clinic. METHODS: We consecutively enrolled men attending an infertility clinic from July 2020 to June 2021. Semen parameters were obtained at initial presentation, and the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale score, and the STOP-BANG Questionnair were completed to assess sleep quality. Embryo outcomes were evaluated after infertility treatment. RESULTS: Of 466 men enrolled, 119 had OAT (OAT group) and 347 had normozoospermia (NS group). There were no differences between the two groups regarding Epworth Sleepiness Scale and STOP-BANG Questionnaire scores. The prevalence of poor sleep quality (Pittsburgh Sleep Quality Index score ≥ 5) in the OAT group was significantly higher than that in the NS group (42% vs. 29%, p = 0.009). A higher rate of poor subjective sleep quality was observed in the OAT group compared with the NS group (p = 0.005) and Pearson's correlations revealed a negative relationship between subjective sleep quality and semen quality. Logistic regression found that subjective sleep quality was independently associated with an increased risk of OAT (adjusted odds ratio = 0.610, p = 0.007). CONCLUSIONS: Men with OAT attending an infertility clinic exhibited poor subjective sleep quality. Improving sleep disturbances may be a target intervention to reduce the risk of OAT. This possibility warrants further investigation.

Vibronic and Cationic Features of 2-Fluorobenzonitrile and 3-Fluorobenzonitrile Studied by REMPI and MATI Spectroscopy and Franck-Condon Simulations.

Fluorinated organic compounds have superior physicochemical properties than general organic compounds due to the strong C-F single bond; they are widely used in medicine, biology, pesticides, and materials science. In order to gain a deeper understanding of the physicochemical properties of fluorinated organic compounds, fluorinated aromatic compounds have been investigated by various spectroscopic techniques. 2-fluorobenzonitrile and 3-fluorobenzonitrile are important fine chemical intermediates and their excited state S1 and cationic ground state D0 vibrational features remain unknown. In this paper, we used two-color resonance two photon ionization (2-color REMPI) and mass analyzed threshold ionization (MATI) spectroscopy to study S1 and D0 state vibrational features of 2-fluorobenzonitrile and 3-fluorobenzonitrile. The precise excitation energy (band origin) and adiabatic ionization energy were determined to be 36,028 ± 2 cm-1 and 78,650 ± 5 cm-1 for 2-fluorobenzonitrile and 35,989 ± 2 cm-1 and 78,873 ± 5 cm-1 for 3-fluorobenzonitrile, respectively. The density functional theory (DFT) at the levels of RB3LYP/aug-cc-pvtz, TD-B3LYP/aug-cc-pvtz, and UB3LYP/aug-cc-pvtz were used to calculate the stable structures and vibrational frequencies for the ground state S0, excited state S1, and cationic ground state D0, respectively. Franck-Condon spectral simulations for transitions of S1 ← S0 and D0 ← S1 were performed based on the above DFT calculations. The theoretical and experimental results were in good agreement. The observed vibrational features in S1 and D0 states were assigned according to the simulated spectra and the comparison with structurally similar molecules. Several experimental findings and molecular features were discussed in detail.

The chromosome-scale genomes of Dipterocarpus turbinatus and Hopea hainanensis (Dipterocarpaceae) provide insights into fragrant oleoresin biosynthesis and hardwood formation.

Dipterocarpaceae are typical tropical plants (dipterocarp forests) that are famous for their high economic value because of their production of fragrant oleoresins, top-quality timber and usage in traditional Chinese medicine. Currently, the lack of Dipterocarpaceae genomes has been a limiting factor to decipher the fragrant oleoresin biosynthesis and gain evolutionary insights into high-quality wood formation in Dipterocarpaceae. We generated chromosome-level genome assemblies for two representative Dipterocarpaceae species viz. Dipterocarpus turbinatus Gaertn. f. and Hopea hainanensis Merr. et Chun. Our whole-genome duplication (WGD) analysis revealed that Dipterocarpaceae underwent a shared WGD event, which showed significant impacts on increased copy numbers of genes related to the biosynthesis of terpene, BAHD acyltransferases, fatty acid and benzenoid/phenylpropanoid, which probably confer to the formation of their characteristic fragrant oleoresin. Additionally, compared with common soft wood plants, the expansion of gene families was also found to be associated with wood formation, such as in CESA (cellulose synthase), CSLE (cellulose synthase-like protein E), laccase and peroxidase in Dipterocarpaceae genomes, which might also contribute to the formation of harder, stronger and high-density timbers. Finally, an integrative analysis on a combination of genomic, transcriptomic and metabolic data from different tissues provided further insights into the molecular basis of fragrant oleoresins biosynthesis and high-quality wood formation of Dipterocarpaceae. Our study contributes the first two representative genomes for Dipterocarpaceae, which are valuable genetic resources for further researches on the fragrant oleoresins and superior-quality timber, genome-assisted breeding and improvement, and conservation biology of this family.

Autler-Townes splitting of three-photon excitation of cesium cold Rydberg gases.

We demonstrate the three-photon Autler-Townes (AT) spectroscopy in a cold cesium Rydberg four-level atom by detecting the field ionized Rydberg population. The ground state |6S1/2〉, two intermediate states |6P3/2〉 and |7S1/2〉 and Rydberg state |60P3/2〉 form a cascade four-level atomic system. The three-photon AT spectra and AT splittings are characterized by the Rabi frequency Ω852 and Ω1470 and detuning δ852 of the coupling lasers. Due to the interaction of two coupling lasers with the atoms, the AT spectrum has three peaks denoted with the letters A, B and C. Positions of the peaks and relative AT splittings, γAB and γBC, strongly depend on two coupling lasers. The dependence of the AT splitting, γAB and γBC, on the coupling laser detuning, δ852, and Rabi frequency, Ω852 and Ω1470 are investigated. It is found that the AT splitting γAB mainly comes from the first photon coupling, whereas the γBC mainly comes from the second photon coupling with the atom. The three-photon AT spectra and relevant AT splittings are simulated with the four-level density matrix equation and show good agreement with the theoretical simulations considering the spectral line broadening. Our work is of great significance both for further understanding the interaction between the laser and the atom, and for the application of the Rydberg atom based field measurement.

Rydberg atom-based AM receiver with a weak continuous frequency carrier.

We demonstrate an atom-based amplitude-modulation (AM) receiver for digital communication with a weak continuous frequency carrier using a Rydberg AC Stark effect in a vapor cell and achieve the operating carrier frequency continuously from 0.1 GHz to 5 GHz at a single Rydberg state. A strong local oscillator (LO) field ELO acts as a gain to shift the Rydberg level to a high sensitivity region, and a weak carrier field ECarr keeps the same frequency with the LO field. The digital baseband signals are encoded onto the ECarr using the amplitude modulation technique with the different modulation frequency. The response of Rydberg atom to the baseband signal is probed via a Rydberg electromagnetically induced transparency (EIT). The measured instantaneous bandwidth of the system is about 230 kHz. To demonstrate the performance of our system for an actual communication, we consider a color image as an example, the received image displays that the bit error rate (BER) is less than 5% when the maximum data transfer rate is about 238 kbps. Meanwhile, our system shows the weak carrier field of ECarr ≥ 13.52 µV/cm can be used for the practical communication with BER less than 5%. Our works break the limitation that EIT-AT based atomic receivers only operate at the near resonant frequencies of the Rydberg transitions, making this emerging of quantum technology close to the practical application with high sensitivity and broad bandwidth.

The role of platelet-related parameters for the prediction of NAFLD in OSAHS patients.

PURPOSE: As the detection of non-alcoholic fatty liver disease (NAFLD) is imperative for the prevention of its complications, we aimed to explore the predictive value of platelet to lymphocyte count ratio (PLR) and white blood cell count to mean platelet volume ratio (WBC/MPV) in relation to the occurrence of NAFLD among patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). METHODS: This was a cross-sectional study consisting of 351 patients with OSAHS (279 with and 72 without NAFLD). The logistic regression analysis was performed to estimate associations between PLR, WBC/MPV, and NAFLD. Finally, the receiver operating characteristic curve (ROC curve) was used to analyze the efficacy of PLR and WBC/MPV in NAFLD prediction. RESULTS: Compared to the OSAHS-only group, there was a rising trend in AHI and TS90% in the OSAHS + NAFLD group. And the logistic regression analysis identified average oxygen saturation (MaSO2), WBC/MPV and PLR as predicted factors (odds ratio [OR] = 1.134, P = 0.031; OR = 7.559, P = 0.018, OR = 0.980, P < 0.001, respectively) for NAFLD in OSAHS patients. Moreover, compared with WBC/MPV, PLR, FLI, and APRI, a combination of WBC/MPV and PLR presented the largest AUC for the detection of NAFLD in BMI < 28 kg/m2 (0.753, 95% CI 0.684-0.822), and in age ≥ 60 years subgroup (0.786, 95% CI 0.692-0.880) in ROC analysis. Meanwhile, a combination of WBC/MPV and PLR presented the second largest AUC for the detection of NAFLD in all subjects (0.743, 95% CI 0.708-0.831), as well as in the age < 60 years subgroup (0.729, 95% CI 0.652-0.806), only ranked after FLI, suggesting the combination of WBC/MPV and PLR has a good predictive value for NAFLD in OSAHS patients. CONCLUSION: We confirmed that the levels of WBC/MPV, PLR, and MaSO2 were closely related to the occurrence of NAFLD among OSAHS patients. Furthermore, our results highlighted the clinical combination of WBC/MPV and PLR levels could act as a simple and effective biomarker for screening NAFLD in patients with OSAHS.

Robot-Assisted Kidney Transplantation: Initial Experience with a Modified Hypothermia Technique.

INTRODUCTION: The aim of the study was to report our initial experience of robot-assisted kidney transplantation (RAKT) with a modified hypothermia technique. METHODS: Between March 2018 and May 2020, 12 patients with end-stage renal disease underwent RAKT at the Chinese PLA General Hospital, and a modified regional hypothermia was implemented by wrapping the kidney in a sealed plastic jacket filled with ice slush. Baseline, surgical, and functional outcomes were analyzed. RESULTS: All surgeries were successfully performed. The mean operative time was 180.5 min, with a mean console time of 133.3 min. Mean warm ischemia, cold ischemia, and rewarming times were 1.5, 135.1, and 48.4 min, respectively. The median blood loss was 50 mL, and the median hospital stay was 9.5 days. No complications were observed. The mean serum creatinine levels were 119.4, 100.5, 108, and 108.5 µmol/L 7 days, 1 month, 6 months, and 1 year postoperatively, respectively. All patients and grafts survived at a median follow-up of 32.2 months. CONCLUSION: RAKT is a safe and feasible procedure for surgical teams with expertise in open kidney transplantation and robotic surgery. Our modification of the hypothermia technique can maintain the kidney at a constant low temperature without repeatedly adding ice and prevent the complication of paralytic ileus.

Assessment of bone mineral density and bone metabolism in young men with obstructive sleep apnea: a cross-sectional study.

BACKGROUND: Hypoxia in obstructive sleep apnea (OSA) patients during sleep may have an effect on bone metabolism. Few data regarding evaluation of bone metabolism in young individuals diagnosed with OSA. In this study, we aim to identify the association between bone mineral density and OSA in young men (≤ 40 years old of age). METHODS: Consecutive male subjects who underwent polysomnography were enrolled. Serum calcium, 25-hydroxyvitamin-D3, ß-isomerized form C-terminal telopeptide of type I collagen, osteocalcin and procollagen type 1 N-propeptide were measured in all participants, and bone mineral density (BMD) at lumbar spine (L1-L4), femoral neck and hip total were determined by dual energy X-ray absorption (DXA). RESULTS: The population consisted of 85 subjects (mean age 35.53 years). The BMD at lumbar spine (L1-L4) in moderate OSA patients was higher than control and severe OSA group significantly (p = 0.036). After adjustment for confounding factors, stepwise multiple linear regression analyses showed LaSO2 (ß = 0.340, p = 0.008) as an independent explanatory variable for Lumbar L1-L4 BMD, LaSO2 (ß = 0.304, p = 0.037), BMI (ß = 0.393, p = 0.008) for femur neck BMD and BMI (ß = 0.720, p = 0.002) for hip total BMD. CONCLUSIONS: Our finding indicated that there was a relationship between OSA and bone metabolism in younger men, and moderate OSA-related hypoxia positively related with BMD. This study also showed that different degrees of recurrent hypoxia had different effects on bone metabolism, a finding that required further investigation.

Pole analysis of EIT-AT spectrum with Rydberg atoms.

We investigate the electromagnetically induced transparency (EIT) and Autler Townes (AT) splitting spectrum with a four-level Rydberg atom by pole analysis of the probe coherence. A pair of poles corresponding to the two peaks of the spectral splitting is observed. The spectral split or the pole positions are affected by the microwave intensity (MW) and the detuning between the probe and the coupling laser. In the absence of any detuning, the two poles coincide and separate again on the imaginary axis of the complex detuning plane at weak MW field. The two poles do not coincide when the probe (coupling) laser is detuned for scanning the coupling (probe) laser frequency. However, under finite detuning, the two poles approach the nearest distance in the absence of any splitting and are separated again in the direction parallel to the imaginary axis. The spectral analysis of the poles provides an alternate way to establish the relationship between the splitting and the intensity of MW, which may play a role in the application of atomic-based MW measurements.

Distinction of electromagnetically induced transparency and Autler-Towners splitting in a Rydberg-involved ladder-type cold atom system.

Electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS) are two similar quantum coherent phenomena but have different mechanisms and applications. Akaike information criteria (AIC), an objective method to discriminate EIT and ATS from an experimental viewpoint, has been employed in a variety of systems. Here we use AIC method to quantitively discriminate a series of spectra of cold atoms in a Rydberg-involved upper-driving ladder-type. The derived weights of EIT and ATS reflect that our spectra change from EIT-ATS intermediate region to ATS-dominated region along Rabi frequency of coupling field increases. We find that there are two factors affecting EIT-ATS weights in a Rydberg-involved three-level system: dephasing rate, induced by the interactions among Rydberg atoms, makes the EIT-ATS crossover move to the direction of low Rabi frequency of coupling field and the experimental noise makes the difference between EIT and ATS weights reduce at elsewhere. Our investigation could provide a meaningful reference for the observations and applications of Rydberg-involved quantum coherent spectroscopy.

Spatial light path analysis and calibration of four-mirror-based monocular stereo vision.

The feasibility and accuracy of four-mirror-based monocular stereo vision (FMSV) are related to the system layout and calibration accuracy, respectively. In this study, a spatial light path analysis method and a calibration method are proposed for an FMSV system. As two-dimensional light path analysis cannot fully characterize the imaging parameters, a spatial light path model is proposed, which allows refinement of the system design. Then, considering the relationship between the lens distortion and the imaging depth of field (DoF), a DoF-distortion equal-partition-based model is established. In the traditional calibration method, the optical axis must be perpendicular to the chessboard. Here, an accurate and practical FMSV calibration method without this constraint is proposed based on the above model. Using the proposed spatial light path analysis technique, a high-accuracy, high-portability FMSV system is constructed and calibrated, for which the average error of the vision-reconstructed distance is 0.0298 mm. In addition, robot path accuracy is evaluated by the system and compared to laser-tracker measurement results. Hence, high accuracy of 0.031 mm is determined for the proposed vision system.