Hybrid lidar-radar for medical diagnostics

• US 7,010,339 B2
• Filed: 07/29/2002
• Issued: 03/07/2006
• Est. Priority Date: 07/29/2002
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Mullen, Linda J., Contarino, Vincent M., Herczfeld, Peter R.
• Primary Examiner(s): Mantis-Mercader, Eleni
• Assistant Examiner(s): Roy, Baisakhi
• Application Number:
  US10/207,642
• Publication Number:
  US 20040019282A1
• Time in Patent Office: 1,317 Days
• Field of Search: 600/407, 600/430, 600/478, 600/9, 600/476, 600/473, 600/182, 600/425, 435/7.23, 424/9.1, 424/1.11, 424/1.49, 606/10, 606/41, 356/301
• US Class Current: 600/430
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24

Abstract

A hybrid lidar-radar system for detecting the presence of objects, such as cancerous tumors, within tissues by detecting reflected signals from the tissue and discriminating the information related to the cancerous tumor from the undesirable backscattering of light created by the tissue itself. The hybrid lidar-radar system utilizes continuous wave light that is preferably modulated at frequencies up to 60 GHz. The present invention filters the return signals from the tissue at a subcarrier modulation frequency so as to reject erroneous information contained in scattered lights, while at the same time retaining the coherent, unscattered and modulated light information so as to provide for an accuracy detection of tumors within tissues.

Claims

1. A hybrid lidar-radar system for detecting the presence of tissue inhomogeneities within tissue by detection of reflected and scattered light signals from the tissue and discriminating information related to cancerous tumors from scattering of light created by the tissue itself, comprising:

a source of microwave energy for providing a microwave subcarrier signal;

a source of continuous wave light for providing and for transmitting toward the tissue an optical carrier signal that is modulated by the microwave subcarrier signal, said source of light transports the microwave subcarrier signal through the tissue and is reflected and scattered by the tissue, said optical carrier signal has a frequency and said source of continuous wave light comprises;

first and second lasers each having an operating wavelength of about 1064 nm, said first and second lasers having an optical frequency difference in a range from 0.01 GHz to 60 GHz, each of said first and second lasers having an output;

a 50/50 optical splitter receiving and combining the outputs of said first and second lasers, said optical splitter having first and second outputs with the first output of the optical splitter transmitted toward the tissue;

a light source optical detector for receiving the second output of said optical splitter and a mixer for mixing it with a reference signal having a frequency slightly offset from the desired modulation frequency, said mixer providing an output serving as an offset and having an intermediate frequency; and

a laser offset locking assembly receiving the output of said mixer and providing an output signal to each of said first and second lasers that provides coherence between said first and second lasers to said offset intermediate frequency;

a detector for detecting the scattered and reflected light and for producing electrical signals indicative thereof; and

an optical detector that provides an output signal to a network analyzer that receives said produced electrical signals and measures phase and amplitude differences between the light scattered from the tissue and said optical carrier signal for the detection of said tissue inhomogeneities.

2. The hybrid lidar-radar system according to claim 1, wherein each of said first and second lasers provide coherent light having a power level of about 700 mW.

3. A method using a hybrid lidar-radar system for detecting the presence of tissue inhomogeneities within tissue by detecting reflected and scattered light signals from the tissue and discriminating information related to cancerous tumors from scattering of light created by the tissue itself comprising the steps:

providing a microwave subcarrier signal;

providing a modulator having said microwave subcarrier signal applied thereto;

providing a source of light that provides an optical carrier signal comprising a reference signal that is transmitted toward the tissue;

modulating said optical carrier signal with said microwave subcarrier signal;

detecting said optical carrier signal comprising said reference signal and scattered modulated light signals all of which produce electrical signals thereof; and

,

measuring said electrical signals to detect phase and amplitude differences between the reflected and scattered light signal and said reference signal so as to determine the presence of said tissue inhomogeneities.

4. The method according to claim 3, wherein said provided source of continuous wave light comprises first and second lasers each having an operating wavelength of about 1064 nm with the first and second lasers having a 15 optical frequency difference in the range from 0.01 GHz to 60 GHz.

5. The method according to claim 3, wherein said detection is performed by a network analyzer.