Automatic detection of quartz glass subsurface defects by laser scattering method based on an ellipsoidal mirror.

With the improvement of quality requirements of optical components, the detection of subsurface defects of optical components has become a key technology. The existing detection methods still have some limitations in detection depth and detection efficiency. In this paper, a defect scattering light collection method based on ellipsoidal mirror model is used to analyze the scattering light collection efficiency under different experimental conditions theoretically, and the favorable conditions for improving the scattering light collection are proposed. After simulation verification, the use of ellipsoidal reflectors to collect scattered light can effectively avoid the impact of surface defects compared to lenses. At the same time, an experimental system based on this method is set up to filter the stray light by mean filtering method. The system detected three scratches (2 µm in width and 252 nm in depth) on the underside of a piece of quartz glass. The results show that the system can clearly detect the subsurface defects of optical components.

Weak static magnetic fields facilitated highly efficient 2,4,6-trichlorophenol removal by sulfurized nanoscale zero-valent iron supported on biochar (BC-SNZVI) at neutral pH.

Sulfurized nanoscale zero-valent iron supported on biochar (BC-SNZVI) has been successfully synthesized for 2,4,6-trichlorophenol (2,4,6-TCP) removal, while was only effectively under acidic conditions. To obtain highly efficient removal of 2,4,6-TCP within a broader pH range, weak static magnetic fields (WMF) was applied in BC-SNZVI/2,4,6-TCP aqueous systems. Results showed 30 mT WMF supported the most extensive 2,4,6-TCP removal, and 87.4% of 2,4,6-TCP (initial concentration of 30 mg/L) was removed by 0.5 g/L BC-SNZVI at neutral pH (pH = 6.8) within 180 min, which was increased by 54.4% compared to that without WMF. The observed rate constant (Kobs) under 30 mT WMF was 2.1-fold greater than that without WMF. Although three typical anions (NO3- (0.5-10.0 mM), H2PO4- (0.05-0.5 mM), and HCO3- (0.5-5.0 mM)) still inhibited 2,4,6-TCP removal, WMF could efficiently alleviate the inhibitory effects. Moreover, 73.1% of 2,4,6-TCP was successfully removed by BC-SNZVI under WMF in natural water. WMF remarkably boosted the dechlorination of 2,4,6-TCP, increasing the 2,4,6-TCP dechlorination efficiency from 45.2% (in the absence of WMF) to 83.8% (in the presence of WMF) by the end of 300 min. And the complete dechlorination product phenol appeared within 10 min. Force analysis confirmed the magnetic field gradient force (FB) moved paramagnetic Fe2+ at the SNZVI surface along the direction perpendicular to the external applied field, promoting the mass-transfer controlled SNZVI corrosion. Corrosion resistance analysis revealed WMF promoted the electron-transfer controlled SNZVI corrosion by decreasing its self-corrosion potential (Ecorr). With the introduction of sulfur, the magnitude of FB doubled and the Ecorr decreased comparing with NZVI. Our findings provide a facile and viable strategy for treating chlorinated phenols at neutral pH.

Picometer-scale optical vortex interferometer using azimuthal complex spectrum analysis.

An interferogram demodulation method based on azimuthal complex spectrum analysis is proposed for achieving picometer-scale accuracy with an optical vortex interferometer (OVI). The OVI uses conjugated p-radial-order Laguerre-Gaussian beams to produce a high-order petal-like interferogram. A camera with a multi-ring pattern written on its sensor is used to convert the interferogram into multiple azimuthal intensity profiles. A phase shift subjected to either uniform surface displacement or axisymmetric non-uniform surface deformation can be retrieved from the complex spectra of the azimuthal intensity profiles at the main frequency components. The experiment verified that the measurement error is 84 pm for a displacement of 10 nm and 0.359 nm for a deformation magnitude of 100 nm. The effect of surface misalignment on the measurement result is also discussed. The proposed method provides an effective and highly accurate method of interferogram demodulation for the OVI and extends the applicability of OVI from uniform surface displacement measurement to axisymmetric non-uniform surface deformation measurement.

Accurate Calibration of a Large Field of View Camera with Coplanar Constraint for Large-Scale Specular Three-Dimensional Profile Measurement.

In the vision-based inspection of specular or shiny surfaces, we often compute the camera pose with respect to a reference plane by analyzing images of calibration grids, reflected in such a surface. To obtain high precision in camera calibration, the calibration target should be large enough to cover the whole field of view (FOV). For a camera with a large FOV, using a small target can only obtain a locally optimal solution. However, using a large target causes many difficulties in making, carrying, and employing the large target. To solve this problem, an improved calibration method based on coplanar constraint is proposed for a camera with a large FOV. Firstly, with an auxiliary plane mirror provided, the positions of the calibration grid and the tilt angles of the plane mirror are changed several times to capture several mirrored calibration images. Secondly, the initial parameters of the camera are calculated based on each group of mirrored calibration images. Finally, adding with the coplanar constraint between each group of calibration grid, the external parameters between the camera and the reference plane are optimized via the Levenberg-Marquardt algorithm (LM). The experimental results show that the proposed camera calibration method has good robustness and accuracy.

Sensitive Oxidation of Sorbitol-Mediated Fe2+ by H2O2: A Reliable TD-NMR Method for Clinical Blood Glucose Detection.

The clinical challenge of high-accuracy blood glucose detection schemes is to overcome the detection error caused by the background interferences in different individuals. H2O2 as the specific product of glucose oxidation can be involved in the Fe2+/Fe3+ conversion and detected by the time-domain nuclear magnetic resonance (TD-NMR) method sensitively. But, in clinical applications, the oxidation of Fe2+ is susceptible to the complex sample substrates. In this work, we sorted out two kinds of possible interference mechanisms of Fe2+ oxidation in the NMR blood glucose detection method and proposed a feasible scheme that uses sorbitol to weaken the adverse effects of interference. We found that sorbitol-mediated Fe2+ can greatly enhance the sensitivity of the T2 value to H2O2. The chain reaction caused by sorbitol can significantly amplify the efficiency of Fe2+ oxidation at the same concentration of H2O2. Thereby, we can achieve the higher dilution multiple of serum samples to reduce the amount of interfering substances involved in the Fe2+/Fe3+ conversion. We justified the accuracy and availability of our method by successfully detecting and confirming the correlation between the T2 decrease and glucose concentration of the serum samples collected from 16 subjects. The sorbitol-Fe2+ glucose detection method with high sensitivity can be further combined with miniature NMR analyzers to satisfy the calibration requirements of glucose monitoring in diabetic patients instead of frequent medical visits.

Sensitivity enhancement in photothermal interferometry by balanced detection of the complex response to moving excitation.

The sensitivity of photothermal detection relies on both the magnitude of the response of a sample to excitation and the way the response is sensed. We propose a highly sensitive photothermal interferometry by addressing the above two issues. One is the use of moving excitation to enable a different manner in sample heating and cooling, which results in a strong thermoelastic response of the sample. The other is the use of a balanced Mach-Zehnder interferometer with a defocused probe beam to sense the complex response induced by the phase delays taking place at the sample surface and in the surrounding air. The method was verified experimentally with a Nd-doped glass to have 68-fold sensitivity enhancement over the classical photothermal common-path interferometry.

High-Performance Ultra-Thin Spectrometer Optical Design Based on Coddington's Equations.

A unique method to design a high-throughput and high-resolution ultrathin Czerny-Turner (UTCT) spectrometer is proposed. This paper reveals an infrequent design process of spectrometers based on Coddington's equations, which will lead us to develop a high-performance spectrometer from scratch. The spectrometer is composed of cylindrical elements except a planar grating. In the simulation design, spot radius is sub-pixel size, which means that almost all of the energy is collected by the detector. The spectral resolution is 0.4 nm at central wavelength and 0.75 nm at edge wavelength when the width of slit is chosen to be 25 µm and the groove density is 900 lines/mm.

Testing System for the Mechanical Properties of Small-Scale Specimens Based on 3D Microscopic Digital Image Correlation.

The testing of the mechanical properties of materials on a small scale is difficult because of the small specimen size and the difficulty of measuring the full-field strain. To tackle this problem, a testing system for investigating the mechanical properties of small-scale specimens based on the three-dimensional (3D) microscopic digital image correlation (DIC) combined with a micro tensile machine is proposed. Firstly, the testing system is described in detail, including the design of the micro tensile machine and the 3D microscopic DIC method. Then, the effects of different shape functions on the matching accuracy obtained by the inverse compositional Gauss-Newton (IC-GN) algorithm are investigated and the numerical experiment results verify that the error due to under matched shape functions is far larger than that of overmatched shape functions. The reprojection error is shown to be smaller than before when employing the modified iteratively weighted radial alignment constraint method. Both displacement and uniaxial measurements were performed to demonstrate the 3D microscopic DIC method and the testing system built. The experimental results confirm that the testing system built can accurately measure the full-field strain and mechanical properties of small-scale specimens.

Dual-loop Sagnac interferometer with a geometric phase shifter for quadrature phase bias locking.

A stable quadrature phase bias is highly demanded in the balanced Sagnac interferometer to achieve sufficient detection sensitivity and unambiguity. We demonstrate a straightforward and effective quadrature phase locking technique in a free-space balanced Sagnac interferometer by using a dual-loop, one for sensing and the other for bias feedback. The sensing loop and the feedback loop operate on linearly polarized beams at two separate wavelengths and overlap for most of the area. A geometric phase shifter showing wavelength independence placed on the common path of the two loops introduces two almost identical nonreciprocal phase shifts between the counterpropagating beams for the two separate wavelengths, so that real-time compensation of the phase bias for the sensing loop can be implemented by the error signal of the feedback loop. Proof-of-concept experimental results demonstrated successful locking of the quadrature phase bias in the presence of signal fading due to the birefringence disturbance. The correction of the residual chromatism of the interferometer is discussed before the conclusion is made.

Heat coupling effect on photothermal detection with a moving Gaussian excitation beam.

A strong photothermal response is beneficial to the measurement of optical and thermal properties of optical materials using the laser-induced thermal mirror method. A highly sensitive asymmetrical thermal mirror method was recently proposed by employing a moving Gaussian excitation beam [Appl. Phys. Lett.114, 131902 (2019)APPLAB0003-695110.1063/1.5080163]. However, the heat transfer across the interface between the thermodynamic system and the surroundings is ignored, which will lead to an error in the absolute measurement of the material properties. To address the problem, we present a theoretical and experimental study of heat transfer within the heated sample and out to the air coupling fluid in the photothermal detection with a Gaussian excitation beam moving at a constant velocity. We analyze the dynamic temperature fields inside the sample and in the surrounding air, and the phase shifts induced by the thermoelastic displacement of the sample (thermal mirror) and the refractive index gradient of air (thermal lens), as well as the diffracted intensity profiles of the probe beam in the detection plane. The experiments are implemented under normal pressure and vacuum, respectively, for a fused silica glass-air heat coupling system to verify the theoretical model. The experimental results show that the thermal lens, due to the heat coupling effect, introduces a signal deviation approximately 4.2% of the total photothermal signal, which is close to the theoretical result of 5%.

Characterization of weakly absorbing thin films by multiple linear regression analysis of absolute unwrapped phase in angle-resolved spectral reflectometry.

The simultaneous determination of t, n(λ), and κ(λ) of thin films can be a tough task for the high correlation of fit parameters. The strong assumptions about the type of dispersion relation are commonly used as a consequence to alleviate correlation concerns by reducing the free parameters before the nonlinear regression analysis. Here we present an angle-resolved spectral reflectometry for the simultaneous determination of weakly absorbing thin film parameters, where a reflectance interferogram is recorded in both angular and spectral domains in a single-shot measurement for the point of the sample being illuminated. The variations of the phase recovered from the interferogram as functions of t, n, and κ reveals that the unwrapped phase is monotonically related to t, n, and κ, thereby allowing the problem of correlation to be alleviated by multiple linear regression. After removing the 2π ambiguity of the unwrapped phase, the merit function based on the absolute unwrapped phase performs a 3D data cube with variables of t, n and κ at each wavelength. The unique solution of t, n, and κ can then be directly determined from the extremum of the 3D data cube at each wavelength with no need of dispersion relation. A sample of GaN thin film grown on a polished sapphire substrate is tested. The experimental data of t and [n(λ), κ(λ)] are confirmed by the scanning electron microscopy and the comparison with the results of other related works, respectively. The consistency of the results shows the proposed method provides a useful tool for the determination of the thickness and optical constants of weakly absorbing thin films.

A GAN-based anomaly detector using multi-feature fusion and selection.

In numerous applications, abnormal samples are hard to collect, limiting the use of well-established supervised learning methods. GAN-based models which trained in an unsupervised and single feature set manner have been proposed by simultaneously considering the reconstruction error and the latent space deviation between normal samples and abnormal samples. However, the ability to capture the input distribution of each feature set is limited. Hence, we propose an unsupervised and multi-feature model, Wave-GANomaly, trained only on normal samples to learn the distribution of these normal samples. The model predicts whether a given sample is normal or not by its deviation from the distribution of normal samples. Wave-GANomaly fuses and selects from the wave-based features extracted by the WaveBlock module and the convolution-based features. The WaveBlock has proven to efficiently improve the performance on image classification, object detection, and segmentation tasks. As a result, Wave-GANomaly achieves the best average area under the curve (AUC) on the Canadian Institute for Advanced Research (CIFAR)-10 dataset (94.3%) and on the Modified National Institute of Standards and Technology (MNIST) dataset (91.0%) when compared to existing state-of-the-art anomaly detectors such as GANomaly, Skip-GANomaly, and the skip-attention generative adversarial network (SAGAN). We further verify our method by the self-curated real-world dataset, the result show that our method is better than GANomaly which only use single feature set for training the model.

Photothermal vortex interferometer with azimuthal complex spectra analysis for the measurement of laser-induced nanoscale thermal lens dynamics.

A photothermal vortex interferometer (PTVI) is proposed to fill the gap of full-field measurement of the laser-induced nanoscale thermal lens dynamics of optical elements. The PTVI produces a multi-ring petal-like interferogram by the coaxial coherent superposition of the high-order conjugated Laguerre-Gaussian beams. The non-uniform optical path change (OPC) profile resulting from the thermal lens causes the petals of the interferogram at the different radii to shift by the different azimuths. To demodulate such an interferogram, an azimuthal complex spectra analysis is presented by using a camera with a pixelated multi-ring pattern written on its sensor to extract multiple azimuthal intensity profiles synchronously from the interferogram. Therefore, the OPC profile can be determined dynamically from the complex spectra of the azimuthal intensity profiles at the main frequency components. An analytical thermophysical model of the thermal lens is given, and the basic principle of the azimuthal complex spectra analysis is revealed. A proof-of-concept experiment is demonstrated using a N-BK7 glass sample heated by a pump laser. The results verified that the PTVI achieves the measurement accuracy of 47 pm with a standard deviation of 358 pm (3σ) and can be used for full-field measurement of the nanoscale OPC profile caused by the thermal lens dynamics. Due to the picometer-scale accuracy of the PTVI, the absorption coefficient and thermal diffusivity of the glass sample were determined to be A0 = 0.126 m-1 and D = 5.63 × 10-7 m2 s-1, respectively, which agree with the nominal ones of A0 = 0.129 m-1 and D = 5.17 × 10-7 m2 s-1. Although the PTVI is only suitable for measuring the rotationally symmetric OPC, it shows less computation burden and hardware complexity, and it is proved to be a highly sensitive and effective tool in studying optical, thermo-physical, and mechanical properties of optical elements.

Rapid estimation approach for glycosylated serum protein of human serum based on the combination of deep learning and TD-NMR technology.

Rapid and precise estimation of glycosylated serum protein (GSP) of human serum is of great importance for the treatment and diagnosis of diabetes mellitus. In this study, we propose a novel method for estimation of GSP level based on the combination of deep learning and time domain nuclear magnetic resonance (TD-NMR) transverse relaxation signal of human serum. Specifically, a principal component analysis (PCA)-enhanced one-dimensional convolutional neural network (1D-CNN) is proposed to analyze the TD-NMR transverse relaxation signal of human serum. The proposed algorithm is proved by accurate estimation of GSP level for the collected serum samples. Furthermore, the proposed algorithm is compared with 1D-CNN without PCA, long short-term memory network (LSTM) and some conventional machine learning algorithms. The results indicate that PCA-enhanced 1D-CNN (PC-1D-CNN) has the minimum error. This study proves that proposed method is feasible and superior to estimate GSP level of human serum using TD-NMR transverse relaxation signals.

Toward surface defect detection in electronics manufacturing by an accurate and lightweight YOLO-style object detector.

In electronics manufacturing, surface defect detection is very important for product quality control, and defective products can cause severe customer complaints. At the same time, in the manufacturing process, the cycle time of each product is usually very short. Furthermore, high-resolution input images from high-resolution industrial cameras are necessary to meet the requirements for high quality control standards. Hence, how to design an accurate object detector with real-time inference speed that can accept high-resolution input is an important task. In this work, an accurate YOLO-style object detector was designed, ATT-YOLO, which uses only one self-attention module, many-scale feature extraction and integration in the backbone and feature pyramid, and an improved auto-anchor design to address this problem. There are few datasets for surface detection in electronics manufacturing. Hence, we curated a dataset consisting of 14,478 laptop surface defects, on which ATT-YOLO achieved 92.8% mAP0.5 for the binary-class object detection task. We also further verified our design on the COCO benchmark dataset. Considering both computation costs and the performance of object detectors, ATT-YOLO outperforms several state-of-the-art and lightweight object detectors on the COCO dataset. It achieves a 44.9% mAP score and 21.8 GFLOPs, which is better than the compared models including YOLOv8-small (44.9%, 28.6G), YOLOv7-tiny-SiLU (38.7%, 13.8G), YOLOv6-small (43.1%, 44.2G), pp-YOLOE-small (42.7%, 17.4G), YOLOX-small (39.6%, 26.8G), and YOLOv5-small (36.7%, 17.2G). We hope that this work can serve as a useful reference for the utilization of attention-based networks in real-world situations.

A phage-based magnetic relaxation switching biosensor using bioorthogonal reaction signal amplification for Salmonella detection in foods.

Phages are uniquely suited for bacterial detection due to their low cost and ability to recognize live bacteria. Herein, our work establishes the proof-of-concept detection of Salmonella in orange juice based on a phage-mediated portable magnetic relaxation switching (MRS) biosensor. The limit of quantification (LOQ) could reach 5 CFU/mL (95 % confidence interval [CI]: 4-7, N = 4) with a linear range of 102-108 CFU/mL, which has improved 10-fold than that without bioorthogonal signal amplification. The recovery rate of the phage-based MRS biosensor was 95.0 % (95 % confidence interval [CI]: 89.0 %-100.9 %, N = 6). The specificity of the phage-based MRS biosensor was 100 % without false-positive results. In addition, this sensor was able to detect <10 CFU per 25 mL of Salmonella in orange juice with 4-h pre-enrichment. The result from the phage-based MRS biosensor is consistent with that from the standard plate count method. This sensor provides a reliable and ultrasensitive detection platform for pathogens.

The influence of arm positions on mechanical dyssynchrony measured by gated myocardial perfusion imaging.

Background: In routine procedures, patient's arms are positioned above their heads to avoid potential attenuation artifacts and reduced image quality during gated myocardial perfusion imaging (G-MPI). However, it is difficult to achieve this action in the acute period following pacemaker implantation. This study aimed to explore the influence of arm positioning on myocardial perfusion imaging (MPI) in different types of heart disease. Methods: This study was conducted retrospectively. A total of 123 patients were enrolled and underwent resting G-MPI using a standard protocol with arms positioned above their heads and again with their arms at their sides. All individuals were divided into 3 groups: the normal group, the obstructive coronary artery disease (O-CAD) group, and the dilated cardiomyopathy (DCM) group. The G-MPI data were measured by QGS software and Emory Reconstruction Toolbox, including left ventricular ejection fraction (LVEF), end-diastolic volume (EDV), end-systolic volume (ESV), extent, total perfusion deficit (TPD), summed rest score (SRS), scar burden, phase standard deviation (SD), and phase histogram bandwidth (BW). Results: In total, extent, TPD, EDV, ESV, LVEF, systolic SD, systolic BW, diastolic SD, and diastolic BW were all significantly different between the 2 arm positions (all P<0.01). On the Bland-Altman analysis, both EDV and ESV with the arm-down position were significantly underestimated (P<0.001). Meanwhile, TPD, extent, and LVEF with the arm-down position were significantly overestimated (P<0.05). Systolic SD, systolic BW, diastolic SD, and diastolic BW were systematically overestimated (P<0.001). In the DCM group (n=52), EDV, ESV, systolic SD, systolic BW, diastolic SD, and diastolic BW were identified as significantly different by the paired t-test between the 2 arm positions (P<0.05). In the O-CAD group (n=32), scar burden, ESV, LVEF, and diastolic BW were significantly different between the 2 arm positions (P<0.05). Conclusions: Systolic and diastolic dyssynchrony parameters and most left ventricular (LV) functional parameters were significantly influenced by arm position in both normal individuals and patients with heart failure (HF) with different pathophysiologies. More attention should be given to LV dyssynchrony data during clinical evaluation of cardiac resynchronization therapy (CRT) implantation procedure.

Diagnostic value of high sensitivity cardiac troponin T (hs-cTnT) in dialysis patients with myocardial infarction.

Background: As a sensitive diagnostic marker for myocardial infarction (MI) in people with normal renal function, elevated high sensitivity cardiac troponin T (hs-cTnT) was often found in chronic kidney disease (CKD) patients requiring dialysis. However, the accuracy of baseline hs-cTnT in the diagnosis of MI (including Type 1 MI (T1MI) and Type 2 MI (T2MI)) in dialysis patients is still controversial. The aim of this study was to retrospectively explore whether there were any clinical indices that could increase the predictive value of hs-cTnT on admission for MI occurrence in dialysis patients. Methods: Here, 136 patients with uremia who underwent regular dialysis with coronary angiography in the First Affiliated Hospital of Nanjing Medical University from August 2017 to October 2021 were enrolled. According to the coronary angiography results and the presence of clinical symptoms, the patients were divided into: (1). AMI group (n = 69; angiography positive) and Control group (n = 67; angiography negative); (2). T1MI group (n = 69; angiography positive), T2MI group (n = 7; angiography negative & symptomatic), and Control group (n = 60; angiography negative & asymptomatic). Results: Here, we found the mean hs-cTnT on admission in the Control group was much lower than that in the AMI group. Hs-cTnT alone had a mediocre predictive performance, with an AUROC of 0.7958 (95% CI: 0.7220, 0.8696). Moreover, the ROC curve of hs-cTnT combined with the Triglyceride (TG), Time of dialysis, and Albumin (Alb) showed a higher sensitivity area [0.9343 (95% CI: 0.8901, 0.9786)] than that of single hs-cTnT. Next, hs-cTnT combined with the TG, Time of dialysis, and Alb also presented a better performance in predicting T1MI [0.9150 (95% CI: 0.8678, 0.9621)] or T2MI (0.9167 [0.9167 (95% CI: 0.8427, 0.9906)] occurrences. Last, these combined variables could better distinguish patient between T1MI and T2MI group than hs-cTnT alone. Conclusions: On admission, a combination of hs-cTnT, TG, Time of dialysis, and Alb presented a higher sensitivity than hs-cTnT alone in predicting MI occurrence in dialysis patients, suggesting a better diagnostic approach for future clinical applications.

Sensitivity analysis of thin-film thickness measurement by vertical scanning white-light interferometry.

The spectral nonlinear phase method and the Fourier amplitude method have been applied to measure the thin-film thickness profile in vertical scanning white-light interferometry (VSWLI). However, both the methods have their disadvantages, and accordingly their applications are limited. In the paper we have investigated the dependence of the sensitivities of both the methods on the thin-film thickness and refractive index, the objective numerical aperture, and the incident light spectral range of VSWLI. The relation of the Fresnel reflection coefficients on the wavelength effect is also discussed. Some important research results reveal that the combination of both Fourier amplitude and nonlinear phase methods may provide a new approach to improve the VSWLI measurement sensitivity for thin-film thickness profile.

Development of a confocal line-scan laser scattering probe for dark-field surface defects detection of transmissive optics.

Dark-field detection has long been used to identify micron/submicron-sized surface defects benefiting from the broadening effect of the actual defect size caused by light scattering. However, the back-side scattering of a transmissive optical slab is inevitably confused with the front-side scattering phenomenon, resulting in deterioration of the signal-to-noise ratio (SNR) of the scattering signal and false alarms for real defect detection. To this end, a confocal line-scan laser scattering probe equipped with optical sectioning ability is proposed to separate the back-side scattering from the front-side scattering. The optical sectioning ability is realized through a confocal light scattering collector, which overcomes the restriction imposed on the numerical aperture (NA) and the field of view (FOV), reaching an FOV length of 90 mm and NA of 0.69. The line-scan principle of the probe protects itself from crosstalk because it produces only a laser spot on the tested surface in an instant. Experimental results verified that the probe has a line-scan length of 90 mm with a uniformity better than 98%, an rms electronic noise of 3.4 mV, and an rms background noise of 6.4 mV with laser on. The probe can reject the false back-side scattering light for a 2 mm thick fused silica slab at 17.1 dB SNR and operate at a high imaging efficiency of 720 mm2/s with a minimum detectability limit of 1.4 µm at 12 dB SNR. This work put forward an effective method with great application value for submicron-sized defect detection in transmissive optics.