摘要 |
Encrypted markers that are not readily detectable can be revealed by treatment with a specific reagent used as a developer to reveal a readily detectable physical property of the marker, such as a characteristic fluorescence emission after excitation with a particular excitation wavelength, or to reveal a visible color. The encrypted marker can be developed in situ, or a sample can be removed by brushing, scraping, swabbing or scratching the marked object or item and developing the encrypted marker or a sample thereof with the appropriate developer to reveal an overt marker or optical signal. The marker can be revealed by exposure of the encrypted marker or a sample thereof to the developer in any suitable form, such as a solution, a slurry, a swab, a solid (such as in granular form), or a gas or a vapor that includes a developer. |