Product | Forensic Video Comparators

By: Forensic Video Comparators  09-12-2011
Keywords: Forensic Investigation, imaging software, forensic video

Forensic Video Comparator (Intelligent Photoelectricity and Spectrum Multifunction Comparison Analyzer)
Price: USD 16,000 (Includes laptop computer) I. Features

Our forensic video comparator is an intelligent photoelectricity and spectrum comparison analyzer useful for forensic investigation in the crime laboratory. It has a light microscope image with spectrum analysis and combines computer image processing. It can be used for differentiating two or more specimens, as well as to magnify the forensic evidence by making use of different light sources and various lengths of light waves incident on the specimens.


  • With the examined forensic object in the same view field under the same light condition, a magnified image can be seen in the video screen for comparison.
  • The two specimens can be viewed independently.
  • The forensic imaging software can store, collect and edit the captured micro images for latr comparison. With various comparison view fields and cutting lines, the user can overlap view fields and join different images together.
  • The forensic comparator can receive and excite two or more wavelength light sources and function very well in the identification of writings either singly or in combination;
  • The equipment is easy to operate, with both the adjustment of the stage and light sources power-controlled and a choice of multi-wave band spectrum;
  • With different accessories, the forensic comparator can also used in the identification of bullet markings; It provides clear printed images with video printing.

Our Forensic Video Comparator is an ideal instrument used to identify finger prints, shot marks, tool traces, seals and forensic document examination. It is also suitable for banks looking at paper currency, courtroom evidence, cultural relics, and to examine banknotes, passports, and other printed documents. Colleges and universities, too, can use it for educational and research purposes into the forensic science field.

II. Technical Parameters and Requirements A. Optical Image Formation and Video Display (See Table 1)
General MagnifyingVideo ImageWorking Distance(mm)
Main Objective0.7X~4.5X ZoomReal Editing measurement75
With Added Objective0.2X~1.35X (Zoom)90

Table 1

B. Reception and Exciter Wave Plate:

254nm(Ultraviolet) 385 nm(Ultraviolet) 540 nm(Yellow) 680nm(Red) 800nm(Infrared) 960 nm (Infrared) 1100 nm(Infrared) C. Image Collecting Card: Image 768X576(PAL),640X480(NTSC) D. Imaging Software: Includes software for imaging.

E. Includes computer and LCD monitor.

III. Component PartsThe forensic video comparator consists of five parts: the main comparator unit, computer, LCD display monitor,, image collecting card, image comparison processing software. (See Fig 1.)

Fig 1: The main member of GSB-4A

IV. The Structure of the Main Comparator system and OperationThe main video comparator unit is made up of an objective lens, light sources, stage, and operating board. (See Fig 1.)
  1. The objective lens: The video comparator has one main objective lens which is fixed on the main body. the system has one extra objective. For a wider view field, use the extra microscope objective.
  2. The light sources: Three light sources are provided¬ócold (24V150W), transmission (27W)and halogen (12V50W). The user has variable intensity illumination, can shine a spotlight and position the light.
  3. The stage: There are two stages on the forensic video comparator: The writing identification stage and rotary stage. The first one has a ground glass surface (see Fig 3), which is used when the added objective is involved. With the transmission light source turned on, the light can go through the ground glass onto the examined objects which are either transparent or semi-transparent. The Trace detection stage (see Fig 3) can be put inside the circular hole in the writing identification stage with the ground glass removed. It is involved when the main objective is in use. The user can adjust the stage by handling the control buttons in the operating board.
  4. The operating board (see Fig 2): Operations are done by mainly handling the buttons in the board. The user can operate them after familiarizing himself with all the functions the board offers.
  5. The accessories for the video comparator: Please see Fig 3. When the ground glass surface is removed from the stage, the user can fit the trace detection stage and the bullet shell holder instead. The holder can grip a bullet shell or other cylinders. The user can put the holder on the trace detection stage, writing identification stage or on the floor of the main member case, according to the length of the examined objects. The rotary bullet shell holder, in combination with the software, can show bullet or shell traces on a plane, so that it is easy for the user to make a direct comparison.

Fig 2: The Operating Board

Fig 3: The Main Accessories

V. Infrared and Ultraviolet Effects and the Application of the Transmission LightWhen used in the identification of writings and forensic documents. In order to see if a questioned document has been altered or covered, the user can press the multi-wave band light reception button, choose the wave plate with proper wave length and adjust the light source. If good ultraviolet effect is desired to display secret fluorescence marks or patterns, the user can press the exciter multi-wave band light button, choose the right wave plate and adjust the light source. If good transmission effect is required to test transparent or semi-transparent objects like negative films, the user can turn on the transmission light (see the operating board in Fig 4) and put the examined object on the ground glass of the writing identification stage. Manual and Sample Images:

Keywords: Forensic Investigation, forensic video, imaging software, Operating Board