To make it possible to form inexpensive element, which is easy for activation and can form the mark having high visibility, by selecting the thickness and the reflectivity of a reflection preventing film so that the reflection of at least one wavelength of visible light becomes minimum by interference.
One layer or a plurality of layers of reflection preventing films are formed on the surface of the thin film or gel-shaped base material comprising quartz, plastics, metal and the like in a pattern shape or wedge shape by a blowing method or the like, and covalent bonding or adsorption is performed. Then, receiving material is attached on the uppermost layer of a reflection preventing film in correspondence with the object material to be analyzed. The refractive index of the base material is made to be approximately equal to the square of the refractive index of the material directly on the base material. Furthermore, the reflection preventing layer has the refraction index of the square root of the product of the refractive index of the base material and the refractive index of atmosphere or the value close to the square root and has the optical thickness of 1/4 of the wavelength of the light, whose reflection is to be measured, or the odd-number times of 1/4. Thus the mark, which has the excellent sensitivity and the more clear color or saturation of the contrast can be generated.
MAUL DIANA M
ETTER JEFFREY B
STARZL TIMOTHY W
