We propose a new method to evaluate coherence properties of wavelength-swept light sources for the optical coherence tomography. The method relies on the depth variation of the noise floor and allows to estimate long coherence length with a limited electrical bandwidth unlike the conventional sensitivity roll-off method. By fitting the theoretically predicted noise-floor variation to the experimental data, we have successfully obtained coherence lengths of 1.6, 0.51, and 0.15m for a microelectromechanically tunable vertical-cavity surface-emitting laser with the sweeping rates of 100, 200, and 400kHz, respectively. The coherence lengths are comparable with those obtained with the roll-off method when the coherence lengths are relatively short.
This paper reports preliminary results from the development and application of a two-dimensional MEMS endoscopic scanner for OCT imaging. A 1 mm diameter mirror provides high aperture over large scan angle and can scan at rates of hundreds of Hz in both axes. The mirror is integrated with focusing optics and a fiber-optic collimator into a package of ~5 mm diameter. Using a broadband femtosecond laser light source, ultrahigh axial image resolution of < 5 um in tissue is achieved at 1.06 um center wavelength. Ultrahigh resolution cross-sectional and three-dimensional OCT imaging is demonstrated with the endoscope with ~12 um transverse resolution and < 5 um axial resolution.
An overview of the current state of the art in scanning micromirror technology for switching, imaging, and beam steering applications is presented. The requirements that drive the design and fabrication technology are covered. Electrostatic, electromagnetic, and magnetic actuation techniques are discussed as well as the motivation toward combdrive configurations from parallel plate configurations for large diameter (mm range) scanners. Suitability of surface micromachining, bulk micromachining, and silicon on insulator (SOI) micromachining technology is presented in the context of the length scale and performance for given scanner applications.
A grism typically consists of a transmission grating attached to a prism and constitutes an important optical element for spectroscopic astronomical observations. Here, we present a new type of grism that includes a volume phase holographic grating and evaluate its performance in detail using the rigorous coupled wave analysis (RCWA). Based on the knowledge gained from this evaluation we were able to design and fabricate a grism prototype with good performance.
High quality imaging technologies have been developed for color inkjet printers with a piezoelectric print head. In these technologies, we have used the MLChips head to eject multi-sized micro droplets in the most suitable placements and added a lower density ink in the cyan and magenta color components for the reproduction of highlighted areas. In addition to this hardware technology, we have developed halftone algorithms to obtain smoother tone reproduction. These technologies greatly decrease noise on the output and achieves very high quality image.
Conference Committee Involvement (2)
Color Imaging IX: Processing, Hardcopy, and Applications IX
20 January 2004 | San Jose, California, United States
Color Imaging VIII: Processing, Hardcopy, and Applications
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.