Fast holography of faces


Mon 20-06-2005
Fast
An ultrafast holography system captures the shape of live subjects...



Facial surgery and forensic science are benefiting from a portable holography system that can capture the shape and texture of faces in an instant.

The system, called digital holographic facial topometry, has been developed by scientists at the Center for Advanced European Studies and Research (Caesar) in Bonn, Germany. It uses a 35 ns green laser pulse from an amplified frequency-doubled Nd:YAG laser to illuminate the patientís face. The reflection from the face is then combined with a reference beam to form a hologram, which is captured on high-resolution (4000 lines per mm) black and white film.

The hologram is digitized to create a three dimensional, textured computer model that is an exact replica of the patientís face. (Credit: Center for Advanced European Studies and Research, Germany)

We use green light because it is eye-safe and provides very good reflectivity without the need to apply a special treatment to the surface of the skin, said Peter Hering, head of Caesarís Holography and Laser group. The extremely short exposure time means that we can create holograms of live subjects without any motion artefacts.

Following chemical development, the hologram is digitized to create a three dimensional computer model that is an exact replica of the patientís face. The resolution of the model is so good, about 0.4 mm, that even skin pores and individual hairs can be visualised. The model is then used to aid surgical planning or forensic science investigations.

Caesar claims that the trolley-mounted system can be assembled and ready for use in less than 20 minutes. It is currently being tested at the Clinic for Reconstructive surgery at University Hospital Basel, Switzerland.

To demonstrate the power of the technique, the Caesar team has been performing live demonstrations on stand 252 in Hall B2 at the Laser 2005 World of Photonics congress with a poodle dog as a subject.
This article was ripped from optics.org