Preparing for Vision 2016 in Stuttgart – Accurate fingerprint identification demo using a high full well capacity camera

An interview with Egidijus Auksorius, Langevin institute

In the last two weeks we posted two blogs related to our multi-camera over CoaXPress demo, this week we give some background information on one of our other demos which will show the Adimec Q-2HFW high full well camera. For the background information we interviewed Egidijus Auksorius from the Langevin institute. He will be present in the Adimec booth at Vision 2016 Stuttgart to show how he uses the Q-2HFW in a Full Field Optical Coherence Tomography (FF-OCT) setup to accurately measure your fingerprint.

Fingerprint as measured with FF-OCT 100 to 200 μm below the finger surface. The white dots are sweat ducts and the black lines are correspond to valleys of the surface fingerprint.

Egidijus has a PhD in Physics obtained at the Imperial College London. He is specialized in complex optical imaging systems. Currently he works at the Langevin institute Paris to develop a new fingerprint scanner in collaboration with Professor Claude Boccara, who invented the Full Field OCT technology. This scanner is more accurate compared to existing methods due to its ability to measure the internal fingerprint.

1. Can you give an introduction of the Langevin institute?

Institut Langevin is a public research laboratory of the Ecole Supérieure de Physique et Chimie Industrielles (ESPCI) Paris, conducting research on physics of many kinds of waves: acoustics, optics, microwaves, shear waves, thermal waves, etc. In particular, the focus is on the development of new imaging and non-destructive testing methods.

2. What kind of research are you conducting with Adimec’s high full well capacity camera?

We use the camera mostly for full field optical coherence tomography (FF-OCT) systems.

3. What is the application of your research? Who will use your research?

The majority of FF-OCT applications are in the biomedical field. Since FF-OCT can achieve isotropic resolution (i.e. identical resolution in all directions) of ~1 μm, unmatched by any other type of OCT, it is being used in biomedical applications that require such high resolution, for example in replacing standard histology. In addition, FF-OCT systems in our laboratory are being developed to image human cornea and retina, among other applications. A specific application where we use the camera the most is imaging internal fingerprints. The advantage of FF-OCT over other types of OCT is that it allows capturing internal fingerprint quicker. There we had to sacrifice the superior resolution afforded by FF-OCT in order to image a large area necessary to capture enough of fingerprint details to be used for person recognition. The camera allows achieving fingerprint images of sufficient quality for that purpose.

4. Why is this camera in particular of interest to you?

This camera has a higher number of pixels, frame rate and full well capacity compared to other conventional silicon-based cameras of similar price currently used in the FF-OCT field. In fact, it can acquire in total 100 times more photoelectrons per second than the conventional cameras, and therefore, it is more suited for FF-OCT.

5. What type of improvement did you see with the HFW camera?

The improvement is manifold. Due to higher number of pixels we can image a larger area and due to the combined effect of higher frame rate and higher full well capacity, we can image deeper because of the improvement in terms of signal-to-noise ratio (we are shot noise limited).

6. Do you use the HFW camera for other applications as well?

We mostly use this camera for static and dynamic FF-OCT and for holography; another application of this camera in our lab is studying, detecting and identifying various viruses in water with the common path interferometric system. 

7. What’s the next step in your research?

The never-ending quest of OCT is to keep increasing the imaging depth and image quality. In the case of FF-OCT, the imaging depth can be increased by either increasing the full well capacity or the frame rate of the camera. Since the current Adimec camera can increase the frame rate by reading fewer pixels, we will investigate if this can indeed help to increase the imaging depth further, although at the expense of the imaging area. Since this camera can accept large light intensities we need to use stronger than usual light sources. To this end, we plan to explore the use of inexpensive yet bright light sources, such as VCSEL arrays or laser diodes. We are also working on new FF-OCT configurations that help to improve the imaging depth and image quality by, for example, rejecting specular reflections through the dark-field detection.

8. Which improvements are required in camera specifications to even get further progress in your research?

It’s hard to ask for a better camera. We are already struggling to use its full potential since we don’t have bright enough light sources to operate camera close to its saturation, which is necessary for its optimal performance. However, by using novel light sources or FF-OCT configurations that allow using light budget more sparingly, we would further benefit from better camera specs, specifically higher frame rate or larger full well capacity. 

9. Was it easy for you to use the CoaXPress interface?

Yes, it was very easy. It is surprising that such large data throughput can be achieved with a simple, robust and compact configuration.