Document Type



Physics (HMC)

Publication Date



We compare the dynamic range of OCT/OCM instruments configured with unbalanced interferometers, e.g., Michelson interferometers, with that of instruments utilizing balanced interferometers and balanced photodetection. We define the dynamic range (DR) as the ratio of the maximum fringe amplitude achieved with a highly reflecting surface to the root-mean-square (rms) noise. Balanced systems achieve a dynamic range 2.5 times higher than that of a Michelson interferometer, enabling an image acquisition speed roughly 6 times faster. This maximum improvement occurs at light source powers of a few milliwatts. At light source powers higher than 30 mW, the advantage in acquisition speed of balanced systems is reduced to a factor of 4. For video-rate imaging, the increased cost and complexity of a balanced system may be outweighed by the factor of 4 to 6 enhancement in image acquisition speed. We include in our analysis the "beat-noise" resulting from incoherent fight backscattered from the sample, which reduces the advantage of balanced systems. We attempt to resolve confusion surrounding the origin and magnitude of "beat-noise", first described by L. Mandel in 1962. Beat-noise is present in both balanced and unbalanced OCT/OCM instruments.


Previously linked to as:,375.

Presented at Conference on Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine VIII [January 26-28, 2004, San Jose, CA] SPIE ISBN: 0-8194-5224-6.

Pdf modified from ILL pdf of published version.

Rights Information

© 2004 International Society of Optical Engineering (SPIE)

Terms of Use & License Information

Terms of Use for work posted in Scholarship@Claremont.

Included in

Physics Commons