Laser Center Research Articles

Thermal Analysis and Impart of Temperature Distribution on the Performance of Additive Manufactured Titanium Alloy Based Composite Coatings

Finite element numerical analysis can be used to solve problems of boundary values. The accuracy of model is depended on the meshing refinement. In aerospace industry, finite element analysis has been used by several researchers to know the influence of temperature distribution on the performance of additive manufactured component parts. Accuracy is better with finer mesh. Complex nature of the additive manufacturing process due to rapid heating and cooling made many researchers to adopt numerical investigation which is made easier than the experimental method. Proper modelling of the process must be thoroughly done for the numerical modelling results to be analyzed. The experiment of ternary titanium alloy of Ti-Al-Si-Cu was carried out with cladding machine of 3000 Watts (CW) Ytterbium Laser System (YLS-2000-TR). This machine is situated at the National Laser Centre in the Council of Scientific and Industrial Research (NLC-CSIR). The characterization was done using the standardization ASTM E3-11 procedure. The results shiw the impart of temperature distribution on the dendritic arm spacing in the microstructures. The rate of cooling imparts on the space between the dendritic arms. The more the space, the more the influence on the coating’s properties

A novel wideband radio frequency measurement based on photonic signal processing

AbstractPhotonic signal processing is a suitable alternative of electronics based processing for wideband frequency detection. We propose a novel technique for the detection of a wide range of frequencies based on photonic signal processing. The unknown frequency to be measured is used to modulate a tunable optical source by implementing single sideband suppressed carrier modulation. The modulated signal is combined with two fixed frequency optical carriers to perform heterodyne detection. The frequency of the tunable laser source is swept until significant power of the beat signal is observed after photodetection. A mathematical expression is presented that can be used to measure the frequency of the unknown electrical signal based on value of the center frequency of tunable laser source. The effect of increasing laser linewidth up to 100 MHz and instantaneous shift in laser center frequency up to 200 MHz has also been demonstrated. It has been shown that the proposed technique can measure almost any radio frequency by simply varying the frequency of the tunable laser source.

Laser therapy is a safe and effective treatment for unwanted hair in adults undergoing male to female sex reassignment.

Reduction in unwanted facial and body hair is an important goal in the process of sex reassignment. Laser treatment is a popular, well-established safe and effective method of reducing unwanted hair growth. In the UK a limited number of laser treatment and electrolysis sessions are publically funded for people undergoing sex reassignment. To date, published evidence on efficacy and adverse effects (AEs) has focused on treatment of women and men not undergoing sex reassignment. In the current study, data were collected prospectively from 2015 to 2020 at a UK regional laser centre. Patients were included if they were transgender women aged >16years old and seeking laser treatment for unwanted hair at any body site. The study demonstrated significant reductions in hair growth and significant patient satisfaction, with no AEs. Laser treatment is a safe and effective method of managing unwanted hair growth in the transgender transfeminine population.

Toward Automated Tissue Classification for Markerless Orthopaedic Robotic Assistance

A markerless computer aided orthopaedic platform will require a complex computer vision system to isolate and track rigid bodies used to localize a robot to a patient. Isolating rigid bodies such as bone requires accurate segmentation and this study explores using diffuse laser reflectivity to accurately classify tissue. Lasers (red at 650nm and infrared – IR – at 850nm) intersected four material types; cartilage, ligament, muscle and metal surgical tools within a controlled cadaveric setup. Images were captured with an infrared CMOS sensor, pre-processed to isolate laser centers, and resized to test information requirements. Images for both laser types were scaled from $5\times5$ pixels to $30\times30$ pixels and trained on a convolutional neural network, GoogLeNet. At sizes above $15\times15$ pixels, the IR laser had a higher classification accuracy, reaching 97.8% at $30\times30$ pixels, whereas the red laser peaked at 94.1%. It was shown as not possible to qualitatively identify materials that were not trained in the network based on their probability outputs. Further work will be performed to classify multiple points in a single scene as a step toward segmenting entire surgical views for markerless Computer Assisted Orthopedic Surgery (CAOS) systems.

Laser wakefield accelerated electron beams and betatron radiation from multijet gas targets

Laser Plasma Wakefield Accelerated (LWFA) electron beams and efficiency of betatron X-ray sources is studied using laser micromachined supersonic gas jet nozzle arrays. Separate sections of the target are used for the injection, acceleration and enhancement of electron oscillation. In this report, we present the results of LWFA and X-ray generation using dynamic gas density grid built by shock-waves of colliding jets. The experiment was done with the 40 TW, 35 fs laser at the Lund Laser Centre. Electron energies of 30–150 MeV and 1.0 × 108–5.5 × 108 photons per shot of betatron radiation have been measured. The implementation of the betatron source with separate regions of LWFA and plasma density grid raised the efficiency of X-ray generation and increased the number of photons per shot by a factor of 2–3 relative to a single-jet gas target source.

Selective retina therapy (SRT) for macular serous retinal detachment associated with tilted disc syndrome.

Tilted disc syndrome (TDS) may be associated with a macular serous retinal detachment (MSRD). However, ideal therapy for this complication is still unestablished yet to date. The purpose of this study is to investigate the effect of selective retina therapy (SRT) for MSRD associated with TDS. This retrospective study included 11 eyes of 10 patients (1 male and 9 females), who were treated with SRT for MSRD associated with TDS, and observed at least 12 months after treatment. The mean age was 56 years old (range 44-66). An SRT laser (527 nm, 1.7 μs, 100 Hz; Medical Laser Center Lübeck, Germany) was used for treatment. The changes of best-corrected visual acuity (BCVA), central macular thickness (CMT), and central choroidal thickness (CCT) were examined. Subfoveal curve height (SFCH) was calculated at baseline. The mean follow-up period was 24.4 months (range 12-48 months). The mean BCVA (logMAR), CMT, and CCT changed from 0.03 ± 0.10, 324 ± 82 μm, and 194 ± 68 μm preoperatively to 0.07 ± 0.17, 274 ± 94 μm, and 188 ± 65 μm at final follow-up, respectively, with significant difference on CMT (BCVA: p = 0.44, CMT: p < 0.05, CCT: p = 0.21). The MSRD disappeared in 6 eyes (55%) and the average number of SRT irradiations until resolution of MSRD was 2.6 times (range 1-5 times). There was no significant association between SFCH and resolution of MSRD (p = 0.19). SRT may promote absorption of MSRD and maintenance of BCVA for TDS. Randomized and prospective clinical studies are needed to evaluate the effectiveness of SRT for MSRD associated with TDS.

High-gain x-ray free-electron laser driven by a laser-plasma accelerator using a vertical gradient optical undulator

Recent advances in the studies of laser-plasma accelerators (LPAs) and optical undulators enable the possibility of designing a compact x-ray free-electron laser (FEL). However, the LPA beams usually have a percent-level energy spread that will degrade the FEL performance. To compensate for the energy spread effect, an optical undulator with a transverse gradient has been proposed, in which a dispersed LPA beam is injected into a horizontally polarized Gaussian laser with a horizontal offset relative to the laser center. Such a scheme, however, leads to an inherent orbit deflection and calls for accurate orbit correction. In this paper, we propose an alternative method that does not induce any orbit deflection and requires less total laser power. In this method, a dispersed LPA beam is sent into an optical undulator with a vertical gradient generated by the combination of a Hermite-Gaussian TEM01 mode laser and a TEM00 mode laser. Simulations suggest that this method is feasible to generate megawatt-level soft x-ray FEL by using an LPA beam with the energy of a few tens of MeV.

A Robust Laser Stripe Extraction Method for Structured-Light Vision Sensing.

Environmental sensing is a key technology for the development of unmanned cars, drones and robots. Many vision sensors cannot work normally in an environment with insufficient light, and the cost of using multiline LiDAR is relatively high. In this paper, a novel and inexpensive visual navigation sensor based on structured-light vision is proposed for environment sensing. The main research contents of this project include: First, we propose a laser-stripe-detection neural network (LSDNN) that can eliminate the interference of reflective noise and haze noise and realize the highly robust extraction of laser stripes region. Then we use a gray-gravity approach to extract the center of laser stripe and used structured-light model to reconstruct the point clouds of laser center. Then, we design a single-line structured-light sensor, select the optimal parameters for it and build a car–platform for experimental evaluation. This approach was shown to be effective in our experiments and the experimental results show that this method is more accurate and robust in complex environment.

Laser research on the African continent

This paper reviews the history and current state of laser and laser-related research on the African continent. The major laser centers in northern, western, and southern Africa are discussed and their current research activities reviewed. Laser-related networks operating on the continent are introduced, and their impact on the development of laser centers is discussed. Commercial companies involved in laser manufacture are identified, and finally, an outlook on future developments will be attempted.

Does PDT have potential in the treatment of COVID 19 patients?

The corona virus pandemic has ignited a proliferation of research aimed at prevention of spread, early diagnosis and treatment. Coincidentally, in recent years the Yorkshire Laser Centre has been engaged in developing the methodology of applying PDT in chronic bronchiectasis. Our methodology is based on Methylene Blue (MB) mediated PDT used topically within the airway. The novelty of the method is the use of a nebulizer to deliver the photosensitizer. We suggest that our protocol and methodology could be modulated for use in respiratory infections of COVID -19.

Legal vs. illegal injectable fillers: The adverse effects comparison study.

Over the past decades, soft-tissue filler injections have become an essential part of cosmetic practice worldwide. Due to the increasing demand, unlicensed practitioners venture in performing this minimally invasive procedure, injecting illegal fillers that pose serious complications. To compare the adverse effects of legal and illegal soft-tissue fillers injected by licensed and unlicensed practitioners. A 10-year retrospective, descriptive, single-center study conducted at the outpatient dermatology department and skin laser center at Siriraj Hospital from January 2009 to December 2019. Patients were identified as having treatment-related complications. Their demographic data, clinical history, and injection history were reviewed. Forty patients with mean age of 37years old were included in the study. Thirty-five of them (87.5%) were female. Illegal soft-tissue fillers were used in 28 patients (70%) and were performed by unlicensed practitioners (18 cases, 64.3%, P=.001). Adverse effects from illegal fillers (26 cases, 92.9%) developed longer than legal fillers (7 cases, 58.3%) (P=.017). Symptoms significantly lasted longer in patients injected with illegal fillers, 10 (0.07-288) weeks, as compared to patients injected with legal fillers 0.75 (0.14-72) weeks (P=.01). Injections from illegal fillers resulted to foreign body reaction (22 cases, 78.6%) and infections (6 cases, 21.4%). Vascular complications were identified in legal fillers injections (5 cases, 41.7%). The incidence of adverse effects and complications from soft-tissue filler injections are superior when performed by novice injectors and unlicensed practitioners using illegal fillers. Proper training of filler injections, selection of appropriate fillers, and early recognition of adverse effects are critically important to the success of treatments.

Preface

On behalf of the conference committee, I feel extremely glad to welcome all experts and participants to the International Laser Technology & Optics Symposium 2019, iLATOS 2019 . We thank all participants for your continuous support to iLATOS conference series. We are so excited to have you all here to participate to our iLATOS 2019 , organized by Laser Center, Universiti Teknologi Malaysia. iLATOS 2019 provides a binding platform for all academicians, researchers, and experts to get together to share current knowledge and findings in the area of, but not limited to laser technology and optics fields. We hope that the conference could provide a meaningful networking and collaborative ties among researchers in their fields.Finally, I would like to express my gratitude towards you all who sincerely contributed to this event in order to make it a success. This wouldn’t have been possible without the support of each and every one present here.

First, do no harm: ethical practice and patients with body dysmorphic disorder

Journal of Aesthetic NursingVol. 9, No. 2 CommentFirst, do no harm: ethical practice and patients with body dysmorphic disorderKathleen LongKathleen LongE: E-mail Address: [email protected]Aesthetic Practitioner, Maxamind, GlasgowSearch for more papers by this authorKathleen LongPublished Online:3 Mar 2020https://doi.org/10.12968/joan.2020.9.2.65AboutSectionsView articleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareShare onFacebookTwitterLinked InEmail View article References American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 2013 Google ScholarBeauchamp TL, Childress JF. Principles of biomedical ethics. 4th edn. Oxford: 1979. Google ScholarBetta Living. Is male vanity at an all-time high in the UK? 2014. https://www.bettaliving.co.uk/blog/articles/2014/02/is-male-vanity-at-an-all-time-high-in-the-uk/ (accessed 24 February 2020) Google ScholarDay K. Branching out from wrinkle treatment: collagen corp. turns cowhide to cash. LA Times. 1985. https://www.latimes.com/archives/la-xpm-1985-11-10-fi-3562-story.html (accessed 24 February 2020) Google ScholarDepartment of Health and Social Care. Keogh report. 2013. https://www.nhs.uk/NHSEngland/bruce-keogh-review/Documents/outcomes/ (accessed 24 February 2020) Google ScholarHardy L. Why women of 40 and 50 are the new ‘ageless generation’. 2017. https://www.telegraph.co.uk/women/life/women-40-50-new-ageless-generation/ (accessed 24 February 2020) Google ScholarHealey N. The ugly truth about body dysmorphic disorder and cosmetic surgery. 2016. https://www.netdoctor.co.uk/healthy-living/a27062/cosmetic-surgery-body-dysmorphic-disorder/ (accessed 24 February 2020) Google ScholarKremer D. Body dysmorphic disorder and plastic surgery. 2017. https://www.harleystreetaesthetics.com/blog/dr-kremers-blog/2017/01/13/body-dysmorphic-disorder-and-plastic-surgery (accessed 24 February 2020) Google ScholarNachshoni T, Kotler M. Legal and medical aspects of body dysmorphic disorder. Med Law. 2007; 26(4):721–735 Google ScholarNuffield Council on Bioethics. Cosmetic procedures practice and promotion ‘cause for serious concern’, says ethics think tank. 2017. https://www.nuffieldbioethics.org/news/cosmetic-procedures-practice-promotion-concern-ethics-tank (accessed 24 February 2020) Google ScholarNolen-Hoeksema S. Could aging be good for women? 2010. https://www.psychologytoday.com/us/blog/the-power-women/201001/could-aging-be-good-women (accessed 24 February 2020) Google ScholarPoupard RJ. Self-esteem from a scalpel: the ethics of plastic surgery. Christian Research Institute. 2012. https://www.equip.org/article/self-esteem-from-a-scalpel-the-ethics-of-plastic-surgery-2 (accessed 24 February 2020) Google Scholarhttps://www.equip.org/article/self-esteem-from-a-scalpel-the-ethics-of-plastic-surgery-2 (accessed 24 February 2020) Google ScholarTorres J. Study: women look in a mirror at least eight times a day. ABC News Radio. 2012. http://abcnewsradioonline.com/health-news/study-women-look-in-a-mirror-at-least-eight-times-a-day.html (accessed 24 February 2020) Google Scholarhttp://abcnewsradioonline.com/health-news/study-women-look-in-a-mirror-at-least-eight-times-a-day.html (accessed 24 February 2020) Google ScholarUNC Aesthetic, Laser & Burn Center. Surgical and non-surgical cosmetic procedures by age. 2013. https://www.uncaestheticandlaser.com/blog/2013/01/surgical-and-non-surgical-cosmetic-procedures-by-age/ (accessed 24 February 2020) Google ScholarVeale D, De Haro L, Lambrou C. Cosmetic rhinoplasty in body dysmorphic disorder. Br J Plast Surg. 2003; 56(6):546–551. https://doi.org/10.1016/s0007-1226(03)00209-1 Crossref, Google ScholarVelimirović A. The importance of the Frida Kahlo self-portrait with thorn necklace and hummingbird. 2018. https://www.widewalls.ch/frida-kahlo-self-portrait-with-thorn-necklace-and-hummingbird/ (accessed 24 February 2020) Google Scholar FiguresReferencesRelatedDetails 2 March 2020Volume 9Issue 2ISSN (print): 2050-3717ISSN (online): 2052-2878 Metrics History Published online 3 March 2020 Published in print 2 March 2020 Information© MA Healthcare LimitedPDF download

Thermal Lagging of Multilayered Structure in Heat-Assisted Magnetic Recording Systems

Abstract In the present study, we numerically investigate the thermal lagging behavior on the hard disk drives in heat-assisted magnetic recording systems via the optical absorption model. The influences of overcoats, laser radius, relative scanning speed, interfacial thermal resistance, and the heat sink layer on the thermal lagging behavior are studied in detail. It is found that the thermal lagging distance, i.e., the horizontal distance between the location of the maximum temperature and the laser center, increases with an increment of speed and/or radius of the laser spot. The overcoats, the interfacial thermal resistance, and the heat sink layer have negligible effects on the lagging distance. Thus, the multilayered disk can be simplified as a single-layer disk for investigating thermal lagging distance. Meanwhile, the horizontal temperature gradient varies with these factors. Different overcoats result in different horizontal temperature gradient owing to the difference of in-plane thermal diffusivity. A laser with a smaller radius or a slower speed leads to a higher horizontal temperature gradient. The thermal resistance influences the horizontal temperature gradient insignificantly. This study may provide useful information for the design of hard disk drives for heat-assisted magnetic recording technologies.

Characterisation and Modelling of Ultrashort Laser-Driven Electromagnetic Pulses

Recent advances on laser technology have enabled the generation of ultrashort (fs) high power (PW) laser systems. For such large scale laser facilities there is an imperative demand for high repetition rate operation in symbiosis with beamlines or end-stations. In such extreme conditions the generation of electromagnetic pulses (EMP) during high intense laser target interaction experiments can tip the scale for the good outcome of the campaign. The EMP effects are several including interference with diagnostic devices and actuators as well as damage of electrical components. The EMP issue is quite known in the picosecond (ps) pulse laser experiments but no systematic study on EMP issues at multi-Joule fs-class lasers has been conducted thus far. In this paper we report the first experimental campaign for EMP-measurements performed at the 200 TW laser system (VEGA 2) at CLPU laser center. EMP pulse energy has been measured as a function of the laser intensity and energy together with other relevant quantities such as (i) the charge of the laser-driven protons and their maximum energy, as well as (ii) the X-ray Kα emission coming from electron interaction inside the target. Analysis of experimental results demonstrate (and confirm) a direct correlation between the measured EMP pulse energy and the laser parameters such as laser intensity and laser energy in the ultrashort pulse duration regime. Numerical FEM (Finite Element Method) simulations of the EMP generated by the target holder system have been performed and the simulations results are shown to be in good agreement with the experimental ones.

Epithelial photorefractive keratectomy vs mechanical epithelial removal followed by corneal crosslinking for keratoconus: the Tel-Aviv Protocol.

To compare the Tel-Aviv Protocol, epithelial photorefractive keratectomy (ePRK) combined with corneal crosslinking (CXL), to CXL with alcohol-assisted epithelial removal (Alc-CXL) for progressive keratoconus. Care-Vision Laser Centers, Tel Aviv, Israel. Retrospective study. All patients underwent Alc-CXL or ePRK, a 50 μm laser ablation of the epithelium with a myopic spherical component and an astigmatic component, followed by CXL. All patients completed at least 1 year of follow-up. A total of 131 eyes of 131 patients were included in the study. Fifty patients (38%) were included in the Tel-Aviv Protocol group, and 81 patients (62%) were included in the Alc-CXL group. There was a significant improvement in uncorrected distance visual acuity (UDVA) (from 1.22 ± 0.75 logarithm of the minimum angle of resolution [logMAR] to 0.49 ± 0.44 logMAR, P < .001), corrected distance visual acuity (CDVA) (from 0.29 ± 0.17 logMAR to 0.16 ± 0.12 logMAR, P < .001), Kmax (from 48.50 ± 3.00 diopters [D] to 46.50 ± 3.00 D, P < .001), and cylinder (from -3.31 ± 1.70 D to -2.32 ± 1.66 D, P < .001) in the Tel-Aviv Protocol group in comparison with nonsignificant changes in the Alc-CXL group in UDVA (from 0.89 ± 0.62 logMAR to 0.81 ± 0.65 logMAR, P = .23), CDVA (from 0.25 ± 0.21 logMAR to 0.21 ± 0.17 logMAR, P = .10), Kmax (from 46.50 ± 4.50 D to 46.00 ± 4.40 D, P = .08), and cylinder (from -2.99 ± 2.05 D to -2.80 ± 1.75 D, P = .39) at the end of the follow-up period. The Tel-Aviv Protocol for progressive keratoconus patients provided good improvement in visual acuity and astigmatism while halting the progression of keratoconus.

Dual-wavelength flash Raman mapping method for measuring thermal diffusivity of the suspended nanowire

In this paper, we present a dual-wavelength flash Raman (DFR) mapping method for measuring the thermal diffusivity of a suspended nanowire. A heating pulse is used to heat the nanowire sample, and a probing pulse of different wavelength is used to measure the increase in temperature. The laser absorption coefficient can be eliminated by normalization, and the thermal diffusivity of the sample can be extracted from the normalized temperature increase. An infinite heat conduction model is used in this method to avoid the influence of boundary thermal resistance. By changing the position of the probing laser center, the measurement sensitivity of thermal diffusivity can be further improved. The position of maximum sensitivity is influenced by the thermal diffusivity of the nanowire, width of the heating pulse, radius of the heating laser spot, and characteristic length of the sample. To comprehensively analyze the influences of the various parameters, obtain the best measurement conditions, and attain maximum sensitivity, we propose a dimensionless physical model to analyze the heat conduction of the suspended nanowire. Based on the analysis of the best dimensionless parameters, the corresponding appropriate measurement conditions can be determined. Sensitivity analysis shows that when the radius of the heating laser spot is 1% of the length of the nanowire, the sensitivity of the DFR mapping method can be more than four times that of the concentric DFR method for measuring the thermal diffusivity of the nanowire.

Cutaneous laser surgery for secondary burn reconstruction: Cost benefit analysis.

Thermal disease presents a major burden to individual patient morbidity, healthcare cost as well as to over all economy. Burns also also represent a significant per-patient utlilisation of finite healthcare resources. Secondary complications in these patients, such as multiple drug resistant organisms, may have a devastating effect. Laser surgery has recently come of age as an optimal tool in the secondary reconstruction of burn injury, that is able to simultaneously address significant sheet scar tightness, hypertrophic, atrophic, and keloid complications, pruritus, microstomia, ectropion, skin graft honeycombing, and improve range of movement whilst reducing the risk of infection to <1%. Yet, cutaneous laser surgery is often underutilised due to the perceived concerns about the sustainability of a new service with relatively high startup cost. We present a dual methodology to explore this concern: an evidence-based background review of the last 5 years of current best evidence, and a 22-year cost-analysis comparison at an established, high volume UK Centre of reconstructive surgery. We report that fiscal viability for laser surgery services for secondary burn reconstruction is supported by: level 2 (one systematic review) level 4 evidence (2 studies) and level 5 evidence (expert reports). Evidence over 22 years from an established super-regional NHS laser centre shows that introduction of this service led to sustained and substantial cost saving, producing excellent surgical results at a fraction of the cost of traditional surgery. Analysis of the potential dollar-effect of these advantages to the general population supports state investment in expertise and capital equipment as a medium to long-term cost saving strategy, which may also aid re-integrating patients into the workforce making a meaningful contribution to the economy.

Hypopigmented macules following quality-switched 1064 nm laser hair removal: A retrospective study

Introduction: Laser hair removal (LHR) is a common procedure in dermatology. LHR using quality-switched (QS) 1064-nm neodymium-doped yttrium aluminum garnet (Nd:YAG) is very popular in our community despite lack of sufficient evidence on its efficacy and safety. Purpose: We report the characteristics of nine patients who developed hypopigmented macules after being treated with QS 1064 nm laser for hair removal. Methods: This was a retrospective study at a laser center in Saudi Arabia conducted between June 2014 and September 2018. Patients who developed white macules following treatment with QS 1064 nm Nd:YAG laser for removal of unwanted hair were included in the study. Results: All patients were Saudi females with a mean age of 28.8 years (range: 25–37 years). Well-defined hypopigmented to depigmented 1–3 mm macules developed after being treated with QS 1064 nm Nd:YAG laser for hair removal. The most commonly affected area was the face. Majority of patients had skin phototype IV. Hypopigmented macules developed after an average of 22 laser sessions (range: 4–48 sessions). None of the patients had either personal or family history of vitiligo. Lesions seem to be difficult to treat, with only two patients responding to topical tacrolimus and excimer laser. Conclusion: Hypopigmented macules might develop after QS 1064 nm LHR. Those macules appear to be resistant to treatment. Further prospective controlled studies needed to elaborate more on the safety profile of this procedure.

Repair Method of Data Loss in Weld Surface Defect Detection Based on Light Intensity and 3D Geometry

Weld surface quality inspection is an indispensable part in the welding automation engineering. When Laser Triangulation Method (LTM) is used to scan the weld surface, external factors will interfere with the laser center line, resulting in data loss and quality detection failure, and massive data loss is difficult to be repaired in the traditional way. In order to improve the quality of weld surface defect detection, it is necessary to find an effective and strong anti-interference method to fix the lost data. This paper presents a method of fixing the data loss caused by external environmental factors in the process of detecting flatbed lap weld surface defects by LTM. The paper includes the analysis of the causes of data loss, its impact for practical applications and a repair method. The repair method derives a formula which is suitable for expressing three-dimensional points on weld surface by combining Bidirectional Reflectance Distribution Function (BRDF) and weld surface section model. The accuracy of the algorithm is verified by experiments on standard block and single weld cross-section. The accuracy of the method up to 92% and the repair rate improved by 30%. The method was tested on flatbed lap weld to confirm its effectiveness in the field of catching surface defects hidden in the lost data.