HawkSpex® Tap

Fields of Research and Development

HawkSpex® Tap is a technology that characterizes transparent liquid and pasty materials directly with a smartphone. A thin layer of the material is applied to the camera lens, which acts like an optical filter. The specific material properties are scanned in combination with the imaging of an application-specific test pattern.


The core of this technology is a smartphone application that identifies major chemical components of liquid or creamy substances or distinguishes them based on their different chemical compositions. Unlike other approaches, this technology does not require any other mechanical, optical or electronic components. This makes it particularly attractive for the consumer market. This technology expands the HawkSpex® Mobile platform, also developed at the Fraunhofer IFF.


Practical Implementation

To take a scan with HawkSpex® Tap, the previously cleaned lens of the back camera is placed on the substance being scanned or the substance is applied, e.g. as a grease film, to the back camera lens with a cloth. Acting as an optical filter, the lens scans this as transmission based on the refraction/diffraction caused by the grease film.

Systems Approach

The physical principle of scanning is geometric and thus largely independent of the difficult-to-control properties of lighting and ambient light. It is based on fundamental physical discoveries, including physical optics articulated by Christiaan Huygens around 1650, the Huygens-Fresnel principle, the Kirchhoff integral theorem and Fraunhofer diffraction (parallel beams of light as a light source).

All that is needed for modern technical implementation on a smartphone is its flash as the illuminator, its back camera as the sensor and an appropriate test pattern, which is recorded with this equipment.