Integration of optical imaging systems with different axial specifications including the maximum measurable range and
the axial resolution expands the axial dynamic range. In this research, an optical time-of-flight and an optical coherence
tomography were integrated, because both methods have a measurable range that overlaps in the submillimeter range. The
integrated optical imaging system has the maximum measurable range of several ten centimeters and the axial resolution
of several micrometers, and also get san inside observation ability derived from the feature of the optical coherence
tomography
KEYWORDS: Photodetectors, Fourier transforms, Modulation, LabVIEW, Distance measurement, Beam splitters, Signal processing, Signal detection, Light, Control systems
In this manuscript, we present an optical time of flight and a focusing system to measure and track a reflective target, respectively. The time-of-flight and tracking system is based on the reflectance of the targets. This system uses a commercially available variable focal length lens that changes focal planes when current is applied. The optical system is mounted on a motorized stage that moves the system closer to or away from the target to be located; This is to expand the dynamic focal range of the system. The system is controlled by a specially designed LabVIEW program that controls the entire system.
Optical coherence tomography (OCT) is a non-invasive technique in biomedical imaging since it provides high axial and lateral resolutions. OCT requires approaching the measurement probe to the sample within the axial range of several millimeters. If there is an initial condition that the distance is unknown; as expected for automatic measurement. In a distance with longer axial range, the time-of-flight (ToF) becomes is useful. In this research, we integrated ToF with sub-millimeter axial resolution and a meter-order axial range; and OCT with micrometer-order axial resolution and a millimeter-order axial measurable range. A spectral-domain (SD-OCT) system composed of a superluminescent diode, optical fibers, and a spectrometer was implemented. ToF system holds a semiconductor laser which is sinusoidally modulated by an electric signal ranging frequency from 0.1 to 1 GHz, a Si PIN photodetector. The ToF and the SD-OCT systems share a common optical path; the phase difference of the sinusoidal signals returning from the sample and reference arms are measured. The importance of the integrated system is that the accuracy of ToF is smaller than the axial measurable range of SD-OCT. The SLD of the SD-OCT system has a central wavelength of 840 nm and a bandwidth of 80 nm. The axial measurable range was 3.7 mm which was calculated from the specifications of the grating and the LSC system. The ToF system has an experimental accuracy of 0.9 mm operating at a frequency of 0.8 GHz. It is enough for the axial resolution measurable in the range of SD-OCT.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.