Optical sensor and method for identifying the presence of skin

• US 7,413,567 B2
• Filed: 02/25/2004
• Issued: 08/19/2008
• Est. Priority Date: 02/25/2003
• Status: Active Grant

• Current Assignee: Channel Investments, LLC
• Original Assignee: SpectraGenics, Inc. (Channel Investments, LLC)
• Inventors: Island, Tobin C., Grove, Robert E., Weckwerth, Mark V.
• Primary Examiner(s): Farah; Ahmed M
• Application Number:
  US10/787,720
• Publication Number:
  US 20040167502A1
• Time in Patent Office: 1,637 Days
• Field of Search: 606 3- 12, 607 88- 91, 128/898
• US Class Current: 606/10
• CPC Class Codes: A61B 18/203 applying laser energy to the outside of the body
• CPC Class Codes: A61B 2017/00057 Light
• CPC Class Codes: A61B 2017/00061 spectrum
• CPC Class Codes: A61B 2017/00066 intensity
• CPC Class Codes: A61B 2017/00172 Pulse trains, bursts, intermittent continuous operation
• CPC Class Codes: A61B 2017/00734 battery operated
• CPC Class Codes: A61B 2018/00005 Cooling or heating of the probe or tissue immediately surrounding the probe
• CPC Class Codes: A61B 2018/00452 Skin
• CPC Class Codes: A61B 2018/00476 Hair follicles
• CPC Class Codes: A61B 2018/2261 with scattering, diffusion or dispersion of light
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure

Abstract

A sensor for detecting the presence of skin is disclosed, one configuration of which uses multiple light emitting diodes, each of a unique wavelength band, and a broad-band photodetector to measure the remission of light at multiple wavelengths from a material being analyzed. Characteristics of the spectral remission of the material are used to discriminate human skin from materials that are not human skin. Further, an aesthetic medical device utilizing such a sensor in which the device is inhibited from operation if skin has not been detected. The incorporation of a skin sensor improves the safety of devices that emit radiation that otherwise would pose a hazard if not directed onto skin.

Claims

1. A skin sensor comprising, a housing having an aperture shaped to be placed against a surface being sensed;

a radiation source inside said housing and positioned to emit radiation in three or more distinct wavelength bands through said aperture and onto said surface being sensed so that radiation is remitted by the surface being sensed;

a detector inside said housing positioned to receive the radiation remitted by said surface being sensed;

a control circuit to power said radiation source so that radiation from each of the three or more distinct wavelength bands is emitted at distinct times;

said control circuit further measuring the remitted radiation for each said three or more distinct wavelength bands to obtain a spectral remittance of said surface being sensed;

said control circuit further comparing the spectral remittance of the surface being sensed to a reference spectral remittance previously determined for skin;

said control circuit providing an indication when the spectral remittance of the surface being sensed is substantially the same as the reference spectral remittance.

2. The skin sensor of claim 1, wherein the radiation source comprises a plurality of light emitting diodes, each emitting radiation in a different one of the three or more distinct wavelength bands.

3. The skin sensor of claim 2, wherein the radiation source includes light emitting diodes each of which emit radiation in a different one of an infra-red, a red, a yellow, a green, or a blue wavelength band.

4. The skin sensor of claim 2, wherein the housing is opaque.

5. The skin sensor of claim 2, wherein the radiation source is controlled to emit modulated radiation in three or more distinct wavelength bands.

6. The skin sensor of claim 1, wherein the detector comprises a plurality of radiation detectors, each responsive to radiation in a different one of the three or more distinct wavelength bands.

7. The skin sensor of claim 1, wherein the detector comprises a single broadband radiation detector.

8. A skin sensor comprising, a housing having an aperture configured to be placed against a surface being queried;

a broad-band radiation source contained within said housing and positioned to emit radiation through said aperture;

three or more detectors inside said housing, each responsive to a distinct wavelength band and positioned to receive radiation remitted by said surface being queried;

a control circuit to power said radiation source;

said control circuit further measuring the remitted radiation for each said distinct wavelength band to determine a spectral remittance of said surface being queried;

said control circuit further comparing the spectral remittance of said surface being queried to a reference spectral remittance for skin; and

said control circuit providing an indication when the spectral remittance of said surface being queried is substantially the same as the reference spectral remittance.

9. The skin sensor of claim 8, wherein each of the three or more detectors is composed of a material inherently sensitive to radiation in a different one of the distinct wavelength bands.

10. The skin sensor of claim 8, wherein each of the three or more detectors comprises a broadband radiation detector and a filter which passes radiation from different ones of the distinct wavelength bands.

11. A dermatological treatment device comprising, a housing having a treatment aperture configured to be placed against a surface;

a source of therapeutic radiation contained within said housing and positioned to emit therapeutic radiation through said aperture;

a skin sensor including a source inside said housing and positioned to emit sensing radiation in three or more distinct wavelength bands through a sensor aperture and onto said surface so that sensing radiation is remitted by the surface;

a detector inside said housing positioned to receive the sensing radiation remitted by said surface;

a control circuit to power said source so that the sensing radiation from each of the three or more distinct wavelength bands is emitted at distinct times;

said control circuit further measuring the remitted sensing radiation for each said three or more distinct wavelength bands to obtain a spectral remittance of said surface;

said control circuit further comparing the spectral remittance of the surface to a reference spectral remittance previously determined for skin; and

said control circuit providing an indication when the spectral remittance of the surface is substantially the same as the reference spectral remittance.

12. The dermatological treatment device of claim 11, wherein the treatment aperture is the same as the sensor aperture;

and emission of said therapeutic radiation by said dermatological treatment device is inhibited if said skin sensor indicates the absence of skin.

13. The dermatological treatment device of claim 12, further comprising a contact sensor which senses a substantial contact between said treatment aperture and said surface;

and wherein emission of said therapeutic radiation is inhibited if said substantial contact is not detected.

14. The dermatological treatment device of claim 11, wherein said treatment aperture and said sensor aperture are distinct from one another, but are located sufficiently close to each other such that whenever said sensor aperture is positioned against a skin surface the entire said treatment aperture is substantially positioned against said skin surface;

and emission of said therapeutic radiation by said dermatological treatment device is inhibited if said skin sensor indicates the absence of skin.

15. The dermatological treatment device of claim 14, further comprising a contact sensor which senses a substantial contact between said treatment aperture and said surface;

and wherein emission of said therapeutic radiation is inhibited if said substantial contact is not detected.

16. A dermatological treatment device comprising, a housing having a treatment aperture configured to be placed against a surface;

a source of therapeutic radiation contained within said housing and positioned to emit therapeutic radiation through said treatment aperture;

a broad-band radiation source contained within said housing and positioned to emit sensing radiation through a sensor aperture and onto said surface;

three or more detectors inside said housing, each responsive to a distinct wavelength band and positioned to receive sensing radiation remitted by said surface;

a control circuit to power said radiation source;

said control circuit further measuring the remitted sensing radiation for each said distinct wavelength band to determine the spectral remittance of said surface;

said control circuit further comparing the spectral remittance of said surface to a reference spectral remittance for skin; and

said control circuit providing an indication when the spectral remittance of said surface is substantially the same as the reference spectral remittance.

17. The dermatological treatment device of claim 16, wherein the treatment aperture is the same as the sensor aperture;

and emission of said therapeutic radiation by said dermatological treatment device is inhibited if said skin sensor indicates the absence of skin.

18. The dermatological treatment device of claim 17, further comprising a contact sensor which senses a substantial contact between said treatment aperture and said surface;

and wherein emission of said therapeutic radiation is inhibited if said substantial contact is not detected.

19. The dermatological treatment device of claim 16, wherein said treatment aperture and said sensor aperture are distinct from one another, but are located sufficiently close to each other such that whenever said sensor aperture is positioned against a skin surface substantially the entire said treatment aperture is positioned against said skin surface;

and emission of said therapeutic radiation by said dermatological treatment device is inhibited if said skin sensor indicates the absence of skin.

20. The dermatological treatment device of claim 19 further comprising, a contact sensor which senses a substantial contact between said treatment aperture and said surface;

and wherein emission of said therapeutic radiation is inhibited if said substantial contact is not detected.

21. A dermatological treatment device used for the treatment of unwanted hair comprising, a light source within a housing;

an electrical circuit including one or more batteries within the housing for energizing the light source to produce output light pulses;

a light path within the housing including an aperture through which eye-safe light pulses are propagated out of the housing having properties sufficient for at least temporary hair-regrowth inhibition; and

a skin sensor which inhibits the operation of the light source when an absence of skin at the aperture is detected by the skin sensor;

wherein the dermatological treatment apparatus has a total weight of no more than 1 kilogram, and occupies no more than 1500 cm³ of volume; and

whereby in use, the dermatologic treatment apparatus produces a fluence on an epidermis of a subject undergoing treatment that is sufficient to at least temporarily inhibit hair regrowth and that has an integrated radiance insufficient to cause eye damage.

22. The dermatological treatment device of claim 21, further comprising an optical diffuser disposed along the light path so that an integrated radiance of the output light pulses is reduced to an eye-safe value;

and whereby in use, the dermatologic treatment has an integrated radiance insufficient to cause eye damage.

23. A dermatological treatment device used for the treatment of unwanted hair comprising, a light source within a housing;

an electrical circuit including one or more batteries within the housing for energizing the light source to produce output light pulses;

a light path within the housing including a treatment aperture through which eye-safe light pulses are propagated out of the housing having properties sufficient for at least temporary hair-regrowth inhibition; and

a skin sensor which inhibits the operation of the light source when an absence of skin at the treatment aperture is detected by the skin sensor including a source inside said housing and positioned to emit sensing radiation in three or more distinct wavelength bands through a sensor aperture and onto a surface positioned opposite the treatment aperture so that sensing radiation is remitted by the surface;

a detector inside said housing positioned to receive the sensing radiation remitted by said surface;

a control circuit to power said source so that the sensing radiation from each of the three or more distinct wavelength bands is emitted at distinct times;

said control circuit further measuring the remitted sensing radiation for each said three or more distinct wavelength bands to obtain a spectral remittance of said surface;

said control circuit further comparing the spectral remittance of the surface to a reference spectral remittance previously determined for skin; and

said control circuit inhibiting the light source when the spectral remittance of the surface is not substantially the same as the reference spectral remittance; and

wherein the dermatological treatment apparatus has a total weight of no more than 1 kilogram, and occupies no more than 1500 cm₃ of volume; and

whereby in use, the dermatologic treatment apparatus produces a fluence on an epidermis of a subject undergoing treatment that is sufficient to at least temporarily inhibit hair regrowth and that has an integrated radiance insufficient to cause eye damage.

24. The dermatological treatment device of claim 23, further comprising an optical diffuser disposed along the light path so that an integrated radiance of the output light pulses is reduced to an eye-safe value;

and whereby in use, the dermatologic treatment has an integrated radiance insufficient to cause eye damage.

25. A dermatological treatment device used for the treatment of acne comprising, a skin sensor including a source inside said housing and positioned to emit sensing radiation in three or more distinct wavelength bands through a sensor aperture and onto a surface positioned opposite an output window so that sensing radiation is remitted by the surface;

a detector inside said housing positioned to receive the sensing radiation remitted by said surface;

a control circuit to power said source so that the sensing radiation from each of the three or more distinct wavelength bands is emitted at distinct times;

said control circuit further measuring the remitted sensing radiation for each said three or more distinct wavelength bands to obtain a spectral remittance of said surface;

said control circuit further comparing the spectral remittance of the surface to a reference spectral remittance previously determined for skin; and

said control circuit indicating an absence of skin when the spectral remittance of the surface is not substantially the same as the reference spectral remittance; and

a light source producing light primarily in a wavelength band of 400 to 450 nm and which is emitted through the output window, wherein the output window is configured to contact an epidermis of a subject undergoing treatment when the light is emitted through the output window; and

wherein the light has an intensity of at least 100 mW/cm² at an emitting surface of the output window; and

further wherein heat conduction through the output window is such that a temperature rise produced in the epidermis by the light is reduced by the contact between the epidermis and the output window, and light emission from the light source is inhibited when the skin sensor indicates an absence of skin at the output window.

26. A dermatological treatment device used for repigmenting skin comprising, a housing configured for handheld manipulation;

one or more electrical batteries within the housing;

a light source in the housing producing light primarily in a wavelength band of 320 to 399 nm; and

an output window through which the light is emitted from the housing and which is configured to contact an epidermis of a subject undergoing treatment when the light is emitted through the output window, wherein the light has a spot size at the output window in the range of 0.01 to 0.5 cm²; and

a skin sensor coupled to inhibit the light source when the skin sensor indicates an absence of skin.

27. The dermatological treatment device of claim 26 wherein the skin sensor includes a source inside said housing and positioned to emit sensing radiation in three or more distinct wavelength bands through a sensor aperture and onto a surface positioned opposite the output window so that sensing radiation is remitted by the surface;

a detector inside said housing positioned to receive the sensing radiation remitted by said surface;

a control circuit to power said source so that the sensing radiation from each of the three or more distinct wavelength bands is emitted at distinct times;

said control circuit further measuring the remitted sensing radiation for each said three or more distinct wavelength bands to obtain a spectral remittance of said surface;

said control circuit further comparing the spectral remittance of the surface to a reference spectral remittance previously determined for skin; and

said control circuit inhibiting the light source when the spectral remittance of the surface is not substantially the same as the reference spectral remittance.

28. A method for detecting the presence of skin, comprising the steps of emitting radiation onto a surface being queried;

receiving radiation remitted by said surface being queried;

measuring the remitted radiation in three or more distinct wavelength bands to determine a spectral remittance of said surface being queried;

comparing the spectral remittance of said surface being queried to a reference spectral remittance for skin; and

indicating if the spectral remittance of said surface being queried is substantially the same as the reference spectral remittance.

29. The method of claim 28, wherein the emitting step includes the step of sequentially emitting radiation in three or more distinct wavelength bands.

30. The method of claim 29, wherein the sequentially emitting step includes the steps of triggering a first radiation source to emit radiation in a first distinct wavelength band;

triggering a second radiation source to emit radiation in a second distinct wavelength band; and

triggering a third radiation source to emit radiation in a third distinct wavelength band.

31. The method of claim 29, wherein the sequentially emitting step includes the step of triggering a broadband radiation source to emit broadband radiation;

filtering the emitted broadband radiation with a first filter to provide filtered radiation in a first distinct wavelength band;

filtering the emitted broadband radiation with a second filter to provide filtered radiation in a second distinct wavelength band; and

filtering the emitted broadband radiation with a third filter to provide filtered radiation in a third distinct wavelength band.

32. The method of claim 28, wherein the measuring remitted radiation step comprises the steps of measuring the remitted radiation with a plurality of radiation detectors, each sensitive to a different one of three or more distinct wavelength bands.

33. The method of claim 28, wherein the emitting step comprises the step of triggering a source of broadband radiation;

and the receiving step comprises the step of receiving the remitted radiation with a broadband detector; and

further including the steps of filtering the emitted broadband radiation with a first filter to produce radiation in a first distinct wavelength band;

measuring the remitted radiation of the first distinct wavelength band with the broadband detector;

filtering the emitted broadband radiation with a second filter to produce radiation in a second distinct wavelength band;

measuring the remitted radiation of the second distinct wavelength band with the broadband detector;

filtering the emitted broadband radiation with a third filter to produce radiation in a third distinct wavelength band; and

measuring the remitted radiation of the first distinct wavelength band with the broadband detector.

34. A skin sensor comprising, a radiation source positioned to emit modulated radiation in three or more distinct wavelength bands through an aperture and onto a surface being sensed so that radiation is remitted by the surface being sensed;

a detector positioned to receive the radiation remitted by said surface being sensed;

a control circuit to power said radiation source so that modulated radiation from each of the three or more distinct wavelength bands is emitted at distinct times;

said control circuit further detecting and measuring the remitted modulated radiation for each said three or more distinct wavelength bands to obtain a spectral remittance of said surface being sensed;

said control circuit further comparing the spectral remittance of the surface being sensed to a reference spectral remittance previously determined for skin;

said control circuit providing an indication when the spectral remittance of the surface being sensed is substantially the same as the reference spectral remittance.