Combined time domain and spectral domain coherence gating for imaging and biosensing, 2010-2015
The project aimed to:
- Develop novel multiple paths configurations for versatile and high resolution measurement and imaging,
- Combine principles of coherence gating with wavefront sensing
- Develop systems combining (i) and (ii) for ophthalmology and microscopy.
- Develop a combined AO-SLO/SSOCT dual wavelength system for high-resolution in-vivo microscopy and ophthalmoscopy.
The main thrust of activity in (i), (ii) and (iii) is combining principles of time domain and spectral domain interferometry.
In the first 30 months, several generic multiple path configurations have been evaluated, which admit multiple novel implementations, such as active loops placed in the interferometer arms or passive loops equipped with frequency shifters only. A particular implementation based on acousto-optic modulators, has allowed acquisition of 6 images at the same time from different depths when using a broadband source. When using a swept source, a multiplication by a factor of three of the axial range determined by the optical source was also demonstrated.
A combination of Shack Hartmann wavefront sensing principle with low coherence interferometry lead to a 250 frame rate coherence gated sensor, capable of distinguishing between aberrations created by different layers in a 5 layer structure. Procedures were developed for the coherence gated principle to work with phase shifting interferometry or with spectral domain interferometry based on tuning the laser emission.
A balance detection spectrometer based OCT configuration, equipped with two InGaAs cameras has proven enhanced performance in terms of elimination of fixed pattern noise and better tolerance to the power fluctuations in the system. Halfway through, the research resulted in 9 peer reviewed papers (6 in open access), 40 communications (9 in proceedings of international conferences), in two book chapters and in a patent application.
The results obtained are presented in the page web of each group member.