Compound parabolic concentrator probe for efficient light collection in spectroscopy of biological tissue.
We describe a compound parabolic concentrator (CPC)-based probe for enhanced signal collection in the spectroscopy of biological tissues. Theoretical considerations governing signal enhancement compared with conventional collection methods are given. A ray-tracing program was used to analyze the throughput of CPC's with shape deviations and surface imperfections. A modified CPC shape with 99% throughput was discovered. A 4.4-mm-long CPC was manufactured and incorporated into an optical fiber-based near-infrared Raman spectrometer system. For human tissue samples, light collection was enhanced by a factor of 7 compared with collection with 0.29-NA optical fibers.
K
K
Tanaka
M T
MT
Pacheco
J F
JF
Brennan Iii
I
I
Itzkan
A J
AJ
Berger
R R
RR
Dasari
M S
MS
Feld