Imaging apparatus and method

• US 20030149346A1
• Filed: 11/25/2002
• Published: 08/07/2003
• Est. Priority Date: 03/03/2000
• Status: Active Grant

• Current Assignee: TeraView Limited
• Original Assignee: TeraView Limited
• Inventors: Ciesla, Craig Michael, Cole, Bryan Edward, Arnone, Donald Dominic
• Granted Patent: US 10,076,261 B2
• Time in Patent Office: Days
• US Class Current: 600/309
• 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
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/4547 Evaluating teeth
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation
• CPC Class Codes: G01N 21/43 by measuring critical angle
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B

Abstract

A range of technique for investigating a sample such as obtaining images and/or spectral information are described. The techniques include a method for deriving structural information about a sample as a continuous function of the depth below the surface of the sample, a method for evaluating a part of the structure of a sample located between two interfaces within the sample, and a contrast enhancing method and apparatus which has a quick image acquisition time.

Claims

1. A method of investigating a sample, the method comprising the steps of:

irradiating a surface of a sample with a pulse of electromagnetic radiation, said pulse having a plurality of frequencies in the range from 25 GHz to 100 THz;

detecting said radiation reflected from the sample and deriving structural information about the sample as a function of depth from the surface of the sample.

2. A method according to claim 1, wherein the sample comprises biological material.

3. A method according to claim 1, wherein the step of deriving structural information about the sample, comprises the step of deriving the absorption or refractive index as a continuous function of depth.

4. A method according to any preceding claim, the method further comprising the step of detecting a reference signal.

5. A method according to claim 4, wherein the reference signal is detected by reflecting radiation from a mirror which is substantially perfectly reflecting.

6. An apparatus for investigating a sample, the apparatus comprising:

means for irradiating a surface of a sample with pulse of electromagnetic radiation, said pulse having a plurality of frequencies in the range from 25 GHz to 100 THz;

means for detecting said radiation reflected from the sample and deriving structural information about the sample as a function of depth from the surface of the sample, means

7. A method of imaging a sample, the method comprising the steps of:

irradiating a sample with a pulse of electromagnetic radiation, said pulse having a plurality of frequencies in the range from 25 GHz to 100 THz;

detecting the amplitude of the radiation reflected from or transmitted by the sample; and

generating an image of sample using the amplitude of the radiation detected at a single point in time.

8. A method according to claim 7, wherein the amplitude of the radiation is detected for a period of time, and the image is generated for a single time point.

9. A method according to claim 8, wherein the step of generating the image comprises the step of generating a plurality of images for a plurality of different time points.

10. A method according to claim 9, further comprising the step of optimising the contrast of the image generated using time points as an optimising parameter.

11. A method according to claim 7, wherein the radiation is only detected for a single time point.

12. An apparatus for generating an image of a sample, the apparatus comprising:

means for irradiating a sample with a pulse of electromagnetic radiation, said pulse having a plurality of frequencies in the range from 25 GHz to 100 THz;

means for detecting the amplitude of the radiation reflected from or transmitted by the sample; and

means for generating an image of sample using the amplitude of the radiation detected at a single point in time.

13. An apparatus according to claim 12, the apparatus further comprising means for displaying a plurality of images generated from different time points.

14. A method of detecting variation in the composition of a sample, the variations being located between a first and second interfaces of the sample, the method comprising the steps of:

irradiating a first part and a second part of a surface of the sample with electromagnetic radiation, the first interface being located closer to the surface than the second interface;

detecting the signal due to reflection of the radiation from the first and second interfaces of the two parts of the sample;

comparing the peak height of the signal from the second interface with that of the first interface in the same part of the sample to produce a corrected second interface signal and comparing the corrected second interface signals.

15. A method according to claim 14, wherein the sample is a tooth and the first and second interfaces are chosen from the external surface of the tooth, the enamel/dentine interface of the pulp cavity/dentine interface.

16. A method according to claim 14, wherein the sample is a human or animal body part and the first and second interfaces are chosen from the outer layer or the skin, the skin/fat interface, or an interface within the skin.

17. A method according to any of claims 14 to 17, further comprising the step of deriving the connected second interface signal for a plurality of parts.

18. A method according to claim 17, wherein the method further comprises the step of generating a plot or image by plotting the connected second signal for a plurality of adjoining parts of the sample.

19. An apparatus for detecting variation in the composition of a sample, the variations being located between a first and second interfaces of the sample, the apparatus comprising:

means for irradiating a first part and a second part of a surface of the sample with electromagnetic radiation, the first interface being located closer to the surface than the second interface;

means for detecting the signal due to reflection of the radiation from the first and second interfaces of the two parts of the sample;

means for comparing the peak height of the signal from the second interface with that of the first interface in the same part of the sample to produce a corrected second interface signal and comparing the corrected second interface signals for the different parts of the sample.

20. A method as substantially hereinbefore described with reference to the accompanying drawings.

21. An apparatus as substantially hereinbefore described with reference to any of the accompanying figures.