Related Experiment Video
Updated: May 1, 2026
Multimodal Imaging and Spectroscopy Fiber-bundle Microendoscopy Platform for Non-invasive, In Vivo Tissue Analysis
Published on: October 17, 2016
Feasibility of Direct Digital Sampling for Diffuse Optical Frequency Domain Spectroscopy in Tissue
Darren Roblyer1, Thomas D O'Sullivan2, Robert V Warren2
1Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA 02115 ; Laser Microbeam and Medical Program (LAMMP), Beckman Laser Institute and Medical Clinic, University of California, Irvine.
Direct digital sampling offers a new method for frequency domain diffuse optical spectroscopy, achieving high precision in measuring tissue optical properties. This technique simplifies instrumentation, potentially lowering costs for biomedical applications like tumor detection.
Area of Science:
- Biomedical optics
- Photonics
- Spectroscopy
Background:
- Frequency domain optical spectroscopy is crucial for biomedical applications such as tumor detection and therapy monitoring.
- Current methods predominantly use analog homodyne or heterodyne detection for measuring photon density waves in tissue.
Purpose of the Study:
- To demonstrate the feasibility of direct digital sampling for frequency domain diffuse optical spectroscopy.
- To evaluate the performance of direct digital sampling using a high-speed analog-to-digital converter.
Main Methods:
- Utilized a 3.6 Gigasample/second 12-bit Analog-to-Digital Converter for direct digital sampling.
- Measured digitally synthesized modulated signals (50-400 MHz) on tissue-simulating phantoms at six near-infrared wavelengths.
- Compared results with a network analyzer-based diffuse optical device.
Main Results:
- Achieved amplitude precision of 1% and phase precision of 0.6 degrees during drift tests.
- Measured optical properties (absorption and scattering) agreed within 3.6% and 2.8% respectively, compared to a conventional system.
- Demonstrated viability across a range of biologically relevant optical properties.
Conclusions:
- Direct digital sampling is a feasible and effective method for frequency domain diffuse optical spectroscopy.
- This digital approach has the potential to significantly reduce system complexity, size, and cost.
- Enables more accessible and potentially widespread use of diffuse optical spectroscopy in biomedical fields.
