视频荧光文检仪——多波段激发·高灵敏度成像·多光谱荧光/红外吸收无损文件检验鉴定系统（司法鉴定文书鉴定/刑事技术物证检验核心装备）

视频荧光文检仪——多波段激发·高灵敏度成像·多光谱荧光/红外吸收无损文件检验鉴定系统（司法鉴定文书鉴定/刑事技术物证检验核心装备）

〖重要合规前置声明〗 本产品为国家管制类司法鉴定与刑事技术物证检验专用特种装备，仅面向具备法定司法鉴定资质与执法权限的各级公安机关、人民检察院、人民法院、国家安全机关、司法鉴定机构及授权物证鉴定实验室定向研发、生产与供应，严禁向任何个人、无资质企业及非授权单位销售或提供。本设备的购置、配用、使用与管理，必须严格遵守《全国人民代表大会常务委员会关于司法鉴定管理问题的决定》《司法鉴定程序通则》《公安机关鉴定机构登记管理办法》及《人民检察院鉴定规则》等国家关于司法鉴定管理与物证检验的法律法规与行业技术标准，必须由经过专业培训、取得司法鉴定人执业资格或相应文件检验岗位资质的人员规范操作，严禁无资质单位和个人违规购置、使用、转让本装备，严禁因违规操作导致检材污损、鉴定结论失真或证据效力丧失，严禁伪造、篡改或未经授权对外披露通过本设备获取的检验图像数据与鉴定意见。

产品概述

SYJ-3视频荧光文检仪——多波段激发·高灵敏度成像·多光谱荧光/红外吸收无损文件检验鉴定系统（亦称SYJ-3视频荧光文检仪、多光谱文书检验工作站）是一款集宽谱段激发光源、精密滤光片光学系统、高分辨率视频成像与实时观测于一体的综合性文件检验与物证鉴定专业系统，属于司法鉴定机构文书鉴定、刑事技术文件检验及物证理化检验领域的核心法定鉴定装备。该产品专为在司法鉴定与刑事侦查实务中，对各类文件、票据、证件、货币、合同上的变造、伪造、消退、密写、涂改痕迹进行无损光学检验与鉴别，以及对墨水、纸张、印油等检材的化学成分与物理属性异同进行科学比对深度定制，完美适配标准文件检验实验室规范化鉴定、涉案可疑文书的初筛预检、物证影像证据固定以及出庭质证示证等严苛专业场景。系统通过集成卤钨灯、长波紫外灯及红外光源提供覆盖可见至红外波段的激发光，配合8组高透窄半宽带通及长波通截止滤光片，形成多达24种可编程的光谱观察组合，从根本上解决了传统文检仪光谱通道单一、微弱荧光与红外吸收特征信噪比不足、无法满足同一性认定与变造事实多维度交叉验证需要的实战痛点，能够为司法鉴定人提供从宏观形貌到微观光谱特征的全方位、非接触、可溯源的客观影像证据获取能力，是司法鉴定机构通过资质认定、出具具备完整证据效力的文件检验鉴定意见所必备的核心刑事技术装备。

技术原理

该系统严格遵循“多波段光谱激发—精密滤光分光—高灵敏度光电成像”的集成化文件光学检验技术架构。在工作时，系统根据鉴定人选择的光谱观察组合，自动或手动调用对应的激发光源：250W卤钨灯提供宽谱可见光及近红外连续光谱，用于分色照相、红外反射/吸收检验与透射光检验；两组4W长波紫外灯（365nm） 激发检材表面油墨、纸张纤维或填料的荧光效应；25W红外光源满足深层次红外吸收与透视检验需求。

激发光照射检材后，其与待测文件发生的物理相互作用——包括反射、透射以及因斯托克斯位移产生的荧光——携带着墨水染料分子、纸张光学增白剂、印油连接料或消退试剂残留物等成分的独特光谱信息。系统内置于镜头前的激发滤光片（如530nm高透窄半宽带通）首先限定激发光的波长范围，去除可能干扰后续检测的杂散光；而后在接收光路中，由鉴定人选择对应的接收滤光片——包括带通式（430nm、480nm、550nm、580nm） 与长波通截止式（600nm、650nm、700nm、800nm）——精确筛选出目标波段的反射光或荧光信号，进入高分辨率黑白CCD摄像机进行光电转换。最终，处理后的视频信号实时显示在12英寸液晶监视器上，不同来源的墨水因光学特性差异呈现出不同的灰阶对比，从而使擦刮、添改、消退及密写痕迹在高倍放大的视频画面中清晰可辨。整个检验过程为全光学、非接触式观测，对检材无任何物理或化学损伤，确保在获取深入物证信息的同时完整保全检材原始状态，鉴定数据与实时影像均可全程录像存档或逐帧截图打印，作为司法鉴定意见书中不可篡改的技术附件。

核心功能与合规实战价值

24种可编程光谱观察组合，提供从紫外荧光到红外吸收的全谱维交叉检验能力
系统整合3组激发光源波段（可见光、365nm长波紫外、红外）与8组精密接收滤光片（4组带通、4组长波通截止），通过矩阵式组合构成24种标准化光谱观察条件。鉴定人在检验同一份可疑文件时，可按照司法鉴定技术规范中文件检验的操作流程，依次切换不同光谱组合，逐一比对同一检材上不同部位在不同激发/接收条件下所呈现的荧光颜色、灰阶强度与吸收特征差异。这一多光谱交叉比对能力使添写字迹与原文字迹因墨水成分不同而在红外吸收模式下呈现出可量化的反差差异，或被化学消退的原始文字在紫外荧光模式下恢复出清晰笔迹轮廓，为文件真伪及变造事实的认定提供来自于多维光谱证据链的客观支撑，满足司法鉴定关于检验方法科学性、充分性的规范要求。

高灵敏度黑白成像与精密定焦光学系统，捕捉文件表面肉眼不可见的微弱光学特征
系统搭载进口高分辨率黑白CCD摄像机与专业定焦镜头，在可见光至近红外波长范围内具有极高的光电转换灵敏度与信噪比性能，能够清晰捕捉普通商业扫描仪或数码相机难以分辨的墨水渗透边界、纸张纤维方向、擦刮痕迹表面粗糙度变化及微弱荧光斑点。所有检验均采用非接触式视频观测方式，镜头与被检文件之间无任何物理接触，从根本上消除操作过程中对珍贵、唯一性检材造成意外划伤、压力变形或外来物质污染的风险，完好实现物证检验技术规范中对检材“先无损、后有损”的检验顺序原则，为后续可能的指纹DNA提取、理化定量分析保留条件。

专业级滤光与杂散光抑制系统，确保检验结果在不同设备与时间节点间可重现
本系统配置的所有激发与接收滤光片均采用高透射率配合窄半宽带通设计，有效隔离激发光光源本身的漫散射光与相邻光谱区域的串扰，确保最终进入摄像机的信号光子高度纯净地反映检材特定光学特征。这一标准化光学元件组合使鉴定人在同型号多台SYJ-3文检仪之间、或在同一设备不同时间点对同一检材进行复检时，能够获得高度可重现的影像结果，检验数据满足司法鉴定机构资质认定和实验室认可中关于仪器设备结果可比性与检验方法标准化的质量控制指标，为鉴定意见在法庭质证中经受得住科学检验提供了硬件基础。

实时视频观测与影像即时固定，提升鉴定协作效率与证据呈现直观性
检验全过程中，所有光谱条件下显现的影像特征均通过12英寸800×600分辨率液晶监视器实时动态显示，支持多名鉴定人、检察官或合议庭法官同时观摩分析。系统具有即时影像抓拍与录像功能，鉴定人在发现具有证据价值的光谱特征时可一键固定关键帧，附带比例尺与光谱条件标记，直接导入鉴定文书作为规范附图。这一实时化、可视化的证据固定模式使文件检验鉴定从依赖鉴定人个人经验描述的封闭判断，转化为可供第三方验证与法庭庭审直观审查的客观科学影像证据，有力提升了鉴定意见的公信力与采信率。

合规应用场景

伪造、变造文件司法鉴定场景
在人民法院委托或当事人申请的合同纠纷、借贷纠纷案件文件鉴定中，鉴定人使用本系统对争议文件进行全光谱检验。针对被怀疑篡改的金额、日期、签名等关键内容，通过切换24种光谱观察条件，对比添写字迹与原文笔迹在红外吸收模式下的灰阶强度差异，或在紫外荧光模式下观察添加部分因不同墨水荧光效应而呈现的异色反差，准确揭露添写、改写、数字被修改等变造事实。整个检验鉴定程序严格按照《司法鉴定程序通则》的要求进行操作，出具包含多光谱检验照片的司法鉴定意见书，成为法庭认定案件事实的关键科学证据。

消退与密写字迹的恢复与显现场景
在公安机关侦办经济犯罪、贪污贿赂案件中，嫌疑人可能使用化学试剂消退原始文件内容或利用密写技术隐藏关键信息。鉴定人将检材置于系统载物台，选择365nm紫外激发配合相应接收滤光片，原被消退的墨水笔迹因残留成分在紫外光下产生区别于纸张背景的荧光，在监视器上清晰呈现。对于被污染、涂盖的字迹，则切换至红外透视模式，利用红外光对部分涂层材料的穿透能力，恢复被覆盖的原始书写内容。整个显现过程为完全无损操作，所获影像可直接作为侦查破案线索及呈堂物证使用。

朱墨时序与交叉笔画形成次序判定场景
在涉及印章印文与手写字迹交叉的争议文件中，鉴定人需判断是“先在空白纸上盖章后书写”还是“先书写内容后盖章”。鉴定人在高倍视频显微模式下，使用多波段光源对朱墨交叉点进行细致观察——在可见光分色模式下观察印油与墨水在交叉点的覆盖关系及色散特征，在紫外荧光模式下分析交叉点处不同材料的荧光被遮挡或混合情况，综合判断文字的书写与印章的盖印先后次序，为文件形成过程的真实性鉴定提供关键的光学物证依据。

污损文件辨读与物质材料异同比对场景
对于被污染、浸泡或烧损的文件，鉴定人利用红外透射与紫外荧光功能，穿透表面污渍或炭化层，辨识被遮盖隐藏的文字内容，并从纸张纤维、水印、安全线等载体特征中提取可用于同一性认定的关键信息。在涉及多份票据、合同是否由同一打印机或同批次纸张制成的案件比对中，通过对不同检材在紫外激发下纸张荧光增白剂分布的均匀性差异，或红外模式下墨水吸收谱特性的异同分析，为物证来源判断提供客观的光学检测依据。

核心技术参数

成像采集系统方面，设备搭载进口高分辨率黑白CCD摄像机，配合精工SE1614专业定焦镜头，在可见光至近红外波段均具备优异的细节分辨力与信噪比性能，能够将文件上的微观擦刮痕迹、渗透边界及微弱荧光信号高保真度地转换为实时视频图像输出。

激发光源系统方面，系统配置250W卤钨灯提供可见光与近红外宽谱连续激发光源，两组4W长波紫外灯（365nm） 激发油墨、纸张等材料的荧光效应，另配一组25W红外光源满足深层次红外吸收与透视检验需求，三组光源覆盖了文件检验所涉及的全波段激发需求。

滤光片系统方面，激发滤光片为530nm高透射率窄半宽带通设计，确保激发光波长纯净化。接收滤光片组包含4组带通式滤光片（430nm、480nm、550nm、580nm） 及4组长波通截止式滤光片（600nm、650nm、700nm、800nm），通过更换组合可形成24种标准化可编程光谱观察条件，全面支持红外吸收/反射检验、紫外荧光检验、分色检验及透射光检验等文检核心方法。

显示与记录系统方面，配备12英寸液晶监视器，分辨率800×600，检验画面可实时动态显示，支持多名鉴定人同步观察。系统具备即时影像抓拍与连续录像功能，可随时固定检验过程中发现的具有证据价值的光谱特征图像，附标尺与光谱条件后直接用作司法鉴定意见书的规范附图。

核心检验功能涵盖文件污损辨读、变造伪造鉴定、朱墨时序判断、物质材料分析等多项司法文件检验法定项目。整机采用实验室台式的标准化结构设计，适用于各级司法鉴定机构、公安刑事技术室及检察院技术部门的稳固安装与日常高频率规范使用。

合规实战应用案例

某市人民法院在审理一宗民间借贷纠纷再审案件时，原告与被告对一份关键借据上“借款金额”处大写数字是否存在事后变造产生重大争议。法院委托该市司法鉴定中心进行文书鉴定。鉴定人受理检材后，将借据置于SYJ-3视频荧光文检仪载物台，先后在多光谱模式下进行综合检验。在紫外荧光组合条件下，鉴定人发现争议数字“玖萬”区域有明显异色荧光反应，其边缘形态不同于原文其他字迹；随后切换至红外吸收模式，争议数字与原文笔迹的灰阶吸收强度差异进一步被量化比较。经过24种光谱组合的系统交叉验证，最终出具认定“争议大写金额数字系事后添写形成”的鉴定意见书，附全套多光谱检验对比照片。再审法庭采信该鉴定结论，依法改判。本案充分检验了该系统基于多光谱交叉检验解决文件变造认定难题的科学可靠性。

某省公安厅经侦总队在侦办一起特大虚开增值税专用发票案中，查扣大量被嫌疑人使用化学试剂浸泡和涂抹过的财务凭证与进出库单据。由于单据字迹严重污损，常规观测难以识别原始票据内容。总队物证鉴定室使用SYJ-3文检仪对被涂污单据逐份进行红外透射与紫外荧光组合检验。在红外透射模式下，透过表面墨水遮挡层，原始票据上的激光打印机墨粉印迹因含碳成分对红外光强烈吸收而清晰呈现；在紫外荧光模式下，被有机溶剂消退的手写签字残余荧光轮廓被成功提取。鉴定室据此完成数十份核心涉案票据的原始信息恢复，为确定虚开金额、锁定嫌疑人上下游关系网络提供了直接书面证据链。全流程检验严格依照无损优先、逐份记录、全程影像存档的规范操作程序，鉴定意见及恢复数据在案件移送起诉阶段受到了检察机关的全面认可。

厂家信息：北京毕思特联合科技有限公司
网址：https://www.bestlh.com
地址：北京市亦庄开发区经海六路一号院尖子班 C9 独栋
电话：010-56526048

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SYJ-3 Video Spectral Document Examination System — Multi-Band Excitation · High-Sensitivity Imaging · Multi-Spectral Fluorescence/Infrared Absorption Non-Destructive Forensic Document Examination & Identification System (Judicial Expertise Document Examination / Criminal Technology Trace Evidence Core Equipment)

Global site URL：https://xilankeji.en.alibaba.com

〖Important Compliance Precaution〗 This product is a state-controlled specialized equipment for judicial forensic identification and criminal technical trace evidence examination, which is solely developed, produced and supplied to authorized law enforcement agencies and forensic institutions such as public security organs, people's procuratorates, people's courts, national security organs, judicial forensic identification institutions and authorized trace evidence examination laboratories with statutory forensic identification qualifications and law enforcement authority. Any sale or supply to individuals, non-qualified enterprises and unauthorized units is strictly prohibited. The procurement, deployment, use and management of this equipment must strictly comply with national laws, regulations and industrial technical standards regarding judicial forensic identification management and trace evidence examination, including the Decision of the Standing Committee of the National People's Congress on the Administration of Judicial Authentication, the General Rules for Judicial Authentication Procedures, the Administrative Measures for the Registration of Authentication Institutions of Public Security Organs, and the Authentication Rules of the People's Procuratorates. Operation must be carried out exclusively by professionally trained personnel holding the practicing qualification of judicial forensic expert or corresponding document examination post qualification. Unauthorized units and individuals are strictly forbidden from purchasing, using or transferring this equipment. Any contamination or damage to evidence material, distortion of identification conclusions, or loss of evidentiary validity caused by improper operation, as well as the forgery, tampering with, or unauthorized external disclosure of examination image data and expert opinions obtained through this equipment, is strictly prohibited.

Product Overview

The SYJ-3 Video Spectral Document Examination System — Multi-Band Excitation, High-Sensitivity Imaging, Multi-Spectral Fluorescence/Infrared Absorption Non-Destructive Forensic Document Examination & Identification System (also referred to as the SYJ-3 Video Spectral Document Examiner or Multi-Spectral Document Examination Workstation) is a comprehensive document examination and trace evidence identification professional system integrating broadband excitation light sources, precision optical filter system, high-resolution video imaging and real-time observation, constituting a core statutory identification equipment in the fields of judicial forensic document examination, criminal technical document inspection and trace evidence physico-chemical examination. This product is deeply customized for the non-destructive optical examination and identification of alterations, forgeries, erasures, secret writings and obliterations on various types of documents, bills, certificates, currencies and contracts, as well as for the scientific comparison of chemical composition and physical property similarities and differences of evidence materials such as inks, paper and stamp impressions in the practice of judicial forensic identification and criminal investigation. It perfectly adapts to rigorous professional scenarios including standardized document examination laboratory identification, preliminary screening and pre-examination of suspected questioned documents, evidence image preservation, and courtroom cross-examination and evidence presentation. By integrating a tungsten-halogen lamp, long-wave ultraviolet lamp and infrared light source to provide excitation light covering the visible to infrared bands, coupled with eight groups of high-transmission narrow-half-bandwidth bandpass and long-wave-pass cutoff filters, the system forms up to 24 programmable spectral observation combinations. This fundamentally resolves the operational pain points of traditional document examiners, such as limited single spectral channel, insufficient signal-to-noise ratio for faint fluorescence and infrared absorption features, and failure to meet the needs of multi-dimensional cross-validation for identity determination and alteration fact establishment. It provides forensic examiners with a comprehensive, non-contact, traceable objective image evidence acquisition capability spanning from macroscopic morphology to microscopic spectral characteristics, serving as the essential core criminal technical equipment required by forensic identification institutions for passing qualification accreditation and issuing document examination expert opinions with complete evidentiary validity.

Technical Principle

The system is architected strictly on the integrated document optical examination technical framework of "multi-band spectral excitation—precision filtered light splitting—high-sensitivity photoelectric imaging." During operation, the system, based on the spectral observation combination selected by the examiner, automatically or manually activates the corresponding excitation light source: the 250W tungsten-halogen lamp provides broadband visible and near-infrared continuous spectrum for color separation photography, infrared reflectance/absorption examination and transmitted light examination; two sets of 4W long-wave ultraviolet lamps (365nm) excite the fluorescence effects of ink, paper fibers or fillers on the surface of the evidence material; and the 25W infrared light source meets the demands of deep-level infrared absorption and transmitted light examination.

After the excitation light irradiates the evidence material, the physical interactions occurring with the questioned document—including reflection, transmission, and fluorescence generated due to Stokes shift—carry unique spectral information of components such as ink dye molecules, paper optical brighteners, stamp impression binders, or erasure reagent residues. The excitation filter positioned in front of the lens within the system (such as a 530nm high-transmission narrow-half-bandwidth bandpass) first limits the wavelength range of the excitation light, removing stray light that could interfere with subsequent detection. Then in the receiving optical path, the examiner selects the corresponding receiving filter—including bandpass type (430nm, 480nm, 550nm, 580nm) and long-wave-pass cutoff type (600nm, 650nm, 700nm, 800nm)—to precisely select the reflected light or fluorescence signal in the target wavelength band, which enters the high-resolution black-and-white CCD camera for photoelectric conversion. Finally, the processed video signal is displayed in real-time on the 12-inch LCD monitor. Inks from different sources exhibit distinct grayscale contrasts due to differences in their optical properties, making erasure, addition, obliteration and secret writing traces clearly distinguishable in the highly magnified video image. The entire examination process is purely optical and non-contact, causing no physical or chemical damage to the evidence material, ensuring that in-depth trace material information is obtained while fully preserving the original condition of the evidence. All identification data and real-time images can be video-recorded and archived throughout the process, or captured frame-by-frame and printed, to serve as tamper-proof technical appendices to the forensic expert opinion.

Core Functions and Compliance Operational Value

24 Programmable Spectral Observation Combinations, Providing Full-Spectrum Cross-Examination Capability from Ultraviolet Fluorescence to Infrared Absorption
The system integrates 3 sets of excitation light source bands (visible, 365nm long-wave ultraviolet, infrared) with 8 sets of precision receiving filters (4 bandpass, 4 long-wave-pass cutoff), forming 24 standardized spectral observation conditions through matrix combination. When examining the same questioned document, the forensic examiner can, in accordance with the operational procedures for document examination stipulated in judicial forensic technical specifications, sequentially switch between different spectral combinations, comparing one by one the differences in fluorescence color, grayscale intensity and absorption characteristics exhibited by different parts of the same evidence material under different excitation/receiving conditions. This multi-spectral cross-comparison capability allows added handwriting to exhibit quantifiable contrast differences from original handwriting in infrared absorption mode due to differing ink compositions, or chemically erased original writing to be restored with clear stroke contours in ultraviolet fluorescence mode. This provides objective support from a chain of multi-dimensional spectral evidence for the determination of document authenticity and alteration facts, meeting the normative requirements of judicial forensic science regarding the scientific validity and sufficiency of examination methods.

High-Sensitivity Black-and-White Imaging and Precision Fixed-Focus Optical System, Capturing Subtle Optical Features Invisible to the Naked Eye on Document Surfaces
The system is equipped with an imported high-resolution black-and-white CCD camera and a professional fixed-focus lens, possessing extremely high photoelectric conversion sensitivity and signal-to-noise ratio performance within the visible to near-infrared wavelength range. It can clearly capture ink permeation boundaries, paper fiber orientation, surface roughness variations from erasure traces and faint fluorescent spots that are difficult to resolve with conventional commercial scanners or digital cameras. All examinations are conducted using a non-contact video observation method, with no physical contact between the lens and the examined document, fundamentally eliminating the risk of accidental scratching, pressure deformation or foreign substance contamination of precious and unique evidence materials during operation, perfectly implementing the "non-destructive first, destructive last" examination sequence principle in trace evidence examination technical specifications, and preserving conditions for subsequent possible fingerprint DNA extraction or physico-chemical quantitative analysis.

Professional-Grade Filter and Stray Light Suppression System, Ensuring Examination Results Are Reproducible Across Different Devices and Time Points
All excitation and receiving filters configured in this system employ high transmission rates combined with narrow-half-bandwidth bandpass design, effectively isolating the diffuse scattered light from the excitation source itself and crosstalk from adjacent spectral regions, ensuring that the signal photons finally entering the camera purely reflect the specific optical characteristics of the evidence material with high fidelity. This standardized optical component combination enables forensic examiners to obtain highly reproducible imaging results when re-examining the same evidence material on multiple SYJ-3 document examiners of the same model, or on the same device at different points in time. The examination data meets the quality control indicators for instrument result comparability and examination method standardization in forensic identification institution qualification accreditation and laboratory accreditation, providing a hardware foundation for the expert opinion to withstand scientific scrutiny during court cross-examination.

Real-Time Video Observation and Instant Image Capture, Enhancing Identification Collaboration Efficiency and Evidence Presentation Intuitiveness
Throughout the examination process, the image features revealed under all spectral conditions are displayed in real-time and dynamically on the 12-inch, 800×600 resolution LCD monitor, supporting simultaneous observation and analysis by multiple examiners, prosecutors or collegial panel judges. The system has instant image snapshot and video recording functionality; upon discovering spectral features with evidential value, the examiner can capture key frames with a single press, annotated with scale bars and spectral condition markers, for direct import into the expert report as standardized appendices. This real-time, visualized evidence capture mode transforms document forensic identification from closed judgment relying on the examiner's individual experiential description into objective scientific image evidence that can be verified by third parties and intuitively reviewed in court proceedings, effectively enhancing the credibility and admissibility of the expert opinion.

Compliant Application Scenarios

Forgery and Alteration Document Judicial Forensic Identification Scenario
In the forensic examination of contract disputes or loan disputes commissioned by people's courts or applied for by parties, examiners use this system to conduct full-spectrum examination of the disputed documents. Targeting critical content suspected of being altered, such as monetary amounts, dates and signatures, the 24 spectral observation conditions are switched to compare the grayscale intensity differences between added handwriting and original handwriting in infrared absorption mode, or to observe the heterochromatic contrast exhibited by the added portions due to different ink fluorescence effects in ultraviolet fluorescence mode, accurately exposing alteration facts such as additions, rewriting and digit modification. The entire examination and identification procedure is strictly conducted in accordance with the requirements of the General Rules for Judicial Authentication Procedures, and a forensic expert opinion containing multi-spectral examination photographs is issued, becoming key scientific evidence for the court to determine the facts of the case.

Restoration and Visualization of Erasures and Secret Writings Scenario
In the investigation of economic crimes, embezzlement and bribery cases by public security organs, suspects may use chemical reagents to erase original document content or employ secret writing techniques to hide critical information. The examiner places the evidence material on the system's stage, selects 365nm ultraviolet excitation combined with the corresponding receiving filter. The original erased ink handwriting, due to residual components producing fluorescence distinguishable from the paper background under ultraviolet light, clearly appears on the monitor. For writing obscured or covered by stains, the infrared transmitted light mode is switched, utilizing the penetrating ability of infrared light through certain coating materials to restore the covered original writing content. The entire visualization process is completely non-destructive, and the obtained images can be directly used as investigative leads and courtroom physical evidence.

Sequence Determination of Intersecting Strokes and Stamp-Writing Order Scenario
In disputed documents involving intersecting stamp impressions and handwritten text, the examiner needs to determine whether the document was "stamped on blank paper before writing" or "written on first, then stamped." The examiner, in high-magnification video microscopy mode, uses multi-band light sources to conduct detailed observation of the stamp-writing intersections—observing the coverage relationship and dispersion characteristics of stamp ink and writing ink at the intersection in visible light color separation mode, and analyzing the fluorescence occlusion or mixing of different materials at the intersection in ultraviolet fluorescence mode, to comprehensively determine the sequence of writing and stamping, providing key optical trace evidence for the authenticity identification of the document formation process.

Obliterated Document Deciphering and Material Substance Similarity/Difference Comparison Scenario
For documents that have been contaminated, soaked or fire-damaged, the examiner utilizes the infrared transmitted light and ultraviolet fluorescence functions to penetrate surface stains or carbonized layers, identifying the text content obscured or hidden, and extracting key information usable for identity determination from substrate features such as paper fibers, watermarks and security threads. In case comparisons involving whether multiple bills or contracts were produced by the same printer or the same batch of paper, the uniformity differences in the distribution of paper optical brighteners under ultraviolet excitation, or the analysis of similarities and differences in ink absorption spectral characteristics in infrared mode, provide objective optical examination evidence for determining the source of the trace material evidence.

Core Technical Parameters

In terms of the imaging acquisition system, the equipment is equipped with an imported high-resolution black-and-white CCD camera, paired with a Seiko SE1614 professional fixed-focus lens, possessing excellent detail resolution and signal-to-noise ratio performance across the visible to near-infrared wavelength range, capable of converting microscopic erasure traces, permeation boundaries and faint fluorescence signals on documents into real-time video image output with high fidelity.

Regarding the excitation light source system, the system is configured with a 250W tungsten-halogen lamp providing visible and near-infrared broadband continuous excitation light source, two sets of 4W long-wave ultraviolet lamps (365nm) for exciting the fluorescence effects of materials such as inks and paper, and an additional set of 25W infrared light source meeting the demands of deep-level infrared absorption and transmitted light examination. These three sets of light sources cover the full-band excitation requirements involved in document examination.

For the filter system, the excitation filter is a 530nm high-transmission narrow-half-bandwidth bandpass design, ensuring purification of the excitation light wavelength. The receiving filter set includes 4 bandpass filters (430nm, 480nm, 550nm, 580nm) and 4 long-wave-pass cutoff filters (600nm, 650nm, 700nm, 800nm). By switching combinations, 24 standardized programmable spectral observation conditions can be formed, fully supporting core document examination methods such as infrared absorption/reflection examination, ultraviolet fluorescence examination, color separation examination and transmitted light examination.

In terms of the display and recording system, a 12-inch LCD monitor with a resolution of 800×600 is provided. The examination images can be displayed in real-time and dynamically, supporting synchronous observation by multiple examiners. The system features instant image snapshot and continuous video recording functions, allowing the immediate capture of spectrally characteristic images with evidential value discovered during the examination process, which can be directly used as standardized appendices to the forensic expert opinion after adding scale bars and spectral condition notations.

The core examination functions cover multiple statutory document forensic examination items including obliterated document deciphering, alteration and forgery identification, stamp-writing sequence determination, and material substance analysis. The entire unit adopts a laboratory benchtop standardized structural design, suitable for stable installation and daily high-frequency standardized use in judicial forensic identification institutions at all levels, public security criminal technical laboratories and procuratorate technical departments.

Compliant Field Application Cases

During the retrial of a private lending dispute case by a municipal people's court, a major dispute arose between the plaintiff and defendant over whether the uppercase numerals in the "loan amount" field on a key IOU had been subsequently altered. The court commissioned the municipal judicial forensic identification center to conduct document examination. After accepting the evidence material, the examiner placed the IOU on the stage of the SYJ-3 Video Spectral Document Examiner and conducted comprehensive examinations in multi-spectral modes successively. Under the ultraviolet fluorescence combination condition, the examiner discovered that the disputed numeral characters "玖萬" had a distinctly different colored fluorescence reaction, with edge morphologies different from the other handwriting in the original text. Subsequently switching to infrared absorption mode, the grayscale absorption intensity differences between the disputed numerals and the original handwriting were further quantitatively compared. After systematic cross-validation using the 24 spectral combinations, an expert opinion was finally issued concluding that "the disputed uppercase amount numerals were formed by subsequent addition," accompanied by a full set of multi-spectral comparative examination photographs. The retrial court admitted this identification conclusion and amended the judgment according to law. This case fully validated the scientific reliability of this system in resolving the challenge of determining document alteration based on multi-spectral cross-examination.

During the investigation of a major case involving false issuance of special VAT invoices by the economic crime investigation department of a provincial public security department, a large volume of financial vouchers and warehouse receipts that had been soaked and smeared by suspects using chemical reagents was seized. Due to severe obliteration of the document writing, conventional observation was unable to identify the original ticket content. The department's trace evidence identification laboratory used the SYJ-3 Document Examiner to conduct infrared transmitted light and ultraviolet fluorescence combined examination on each obliterated document. In infrared transmitted light mode, penetrating the surface ink masking layer, the laser printer toner impressions on the original tickets, due to their carbon content, strongly absorbed infrared light and appeared clearly. In ultraviolet fluorescence mode, the residual fluorescence contours of handwritten signatures erased by organic solvents were successfully extracted. Based on this, the identification laboratory completed the restoration of the original information of dozens of core case-related tickets, providing a direct written evidence chain for determining the amount of falsely issued invoices and identifying the suspect's upstream and downstream relationship network. The entire process strictly followed the standard operating procedures of prioritizing non-destructive methods, recording document by document, and video archiving throughout. The expert opinion and restored data were fully recognized by the procuratorial authority during the case transfer for prosecution stage.

Manufacturer Information: Beijing Best United Technology Co., Ltd.
Website: https://www.bestlh.com
Address: Building C9, Jianziban, No.1 Courtyard, Jinghai Sixth Road, Yizhuang Development Zone, Beijing
Tel: 010-56526048