Problem
Up until now the forensic audio industry and the magnetic tape industry as well as others have been using a number of techniques to try to gaze into the illusive world of magnetic fields laid down on magnetic media. As it applies to the forensics industry there is a basic need to analyze the magnetic fields on tapes to see if they have been overwritten or to see if a particular tape recorder can be linked to a particular tape. Until now this has been done with ferro-fluid which is a liquid mixture applied to tapes and other media so that the magnetic force lines (also known as bitter patterns) can be visually seen. A tape is then micro-photographed with a camera attached to a microscope. There are a number of limitations in using ferro-fluid such as application problems and drying problems as well as limitations to the amount of depth or magnetic intensity that can be captured. |
Solution
The solution proposed here is to remove the guess work that ferro-fluids can present and take the entire process into the digital domain. This is done by using a very sensitive hard drive read head element just like that found in today's hard drives and with micron (million's of a meter) accuracy raster scan a magnetic surface while recording the precise position as well as the intensity of magnetic fields. This information is then fed into a computer and manipulated for 2D or preferably 3D viewing. A very accurate picture of the media can be had in this manner, one, it is believed, that will be much more detailed than the current state-of-the-art ferro-fluid both in dynamic range as well as spatial resolution. There are devices now that can do this sort of thing called Magnetic Force Microscopes but they are limited in the amount of area that can be viewed (usually in the millimeters or less) as well as limited by surface roughness of the tape itself. In addition they are extremely expensive usually around $250K. This device can be manufactured for about $5K to $10K thus putting it in the hands of audio engineers and others. A disclosure document has been filed with the patent office on this concept. |
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