D6.3 - Intensity based optical measurement of cornea vibration
- AMA Conferences 2017
2017-05-30 - 2017-06-01
- Proceedings Sensor 2017
- D6 - Mechanical Sensors: Special Applications
- J. Osmers, M. Sorg, A. Fischer - University of Bremen (Germany)
- 522 - 526
In order to measure the dynamic behavior of eyes for yielding the intraocular pressure an optical, intensity-based sensor approach is developed. The challenge is to emit less than 1 mW of power to avoid harming the eye while coping with the low reflection of the eye of 4% for normal incidence. With solely analog infrared diodes and phototransistors the vibration of the cornea of an enucleated porcine eye is demonstrated to be detectable for the whole frequency range of its eigenvalues. For demonstrating the contactless measurement of the eye vibration response that goes with the pressure excitation, the cornea was coated with TiO2 powder first. An optimization of the optical arrangement that maximizes the reflected light power finally enables measurements without coating. As a result, the signal-to-noise ratio of the proposed sensor setup for contactless eye vibration measurements could be enhanced from 24 dB to 46 dB. The expected resolution of the proposed sensor for the IOP measurement is calculated to σ(IOP) < 3mmHg in the physiological range, which gives high application potential.