Apparatus for optically measuring the three-dimensional surface shape and inner structure of an object

• US 4,857,748 A
• Filed: 07/17/1987
• Issued: 08/15/1989
• Est. Priority Date: 07/18/1986
• Status: Expired due to Term

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Takiguchi, Yoshihiro
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Chatmon, Eric F.
• Application Number:
  US07/074,879
• Time in Patent Office: 760 Days
• Field of Search: 250/213 VT, 250/368, 250/227, 250/560, 250/561, 356/375, 356/376, 356/379, 356/380
• US Class Current: 250/559.21
• CPC Class Codes: A61B 5/0062 Arrangements for scanning
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/1076 for measuring dimensions inside body cavities, e.g. using catheters A61B3/1005 takes precedence
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures

Abstract

An apparatus for optically measuring a three-dimensional surface shape and inner structure of a three-dimensional object without destruction of the object. When a light pulse having a short pulse width is applied to the object, there are observed a flux of light pulses reflected from or transmitted through the object which has information on the three-dimensional surface shape and inner structure of the object. This apparatus optically measures and analyzes in the order of a picosecond the intensity distribution of the light pulses from the object with time and space, to thereby obtain a complete three-dimensional image of the object.

Claims

1. An apparatus for optically measuring a three-dimensional surface shape and inner structure of an object, comprising:

a pulse light source for generating pulsed light having a first pulse width;

light conducting means for guiding said pulsed light from said pulse light source to said object;

light detecting means for detecting one of a flux of reflected light pulses from a flux of transmitted light pulses through said object and measuring the change of the intensity of said one flux with respect to time and space, each of said flux of reflected light pulses and flux of transmitted light pulses having a time-delay distribution; and

analyzing means for analyzing outputs of said ultrahigh speed light detecting means.

2. An apparatus as claimed in claim 1, wherein said light conducting means comprises an optical fiber, one end of said optical fiber being inserted into the inside of said object to guide said pulsed light into said object.

3. An apparatus as claimed in claim 2, said apparatus further comprising an optical system for focusing light pulses transmitted through said object onto an input portion of said ultrahigh speed light detecting means.

4. An apparatus as claimed in claim 2, further comprising an optical image fiber having one end thereof inserted into the inside of said object, said flux of reflected light pulses being fed from the inside of said object by the optical image fiber and transmitted to said ultrahigh speed light detecting means.

5. An apparatus as claimed in claim 4, said apparatus further comprising an optical system for focusing the output of said optical image fiber onto an input portion of said ultrahigh speed light detecting means.

6. An apparatus as claimed in claim 1, wherein said light conducting means comprises a first optical system for irradiating said object with said pulsed light from said pulse light source.

7. An apparatus as claimed in claim 6, said apparatus further comprising a second optical system for focusing said flux of reflected light pulses from said object onto an input portion of said ultrahigh speed light detecting means.

8. An apparatus as claimed in claim 6, said apparatus further comprising an optical image fiber having one end thereof inserted into the inside of said object, said flux of transmitted light pulses being fed from the outside to the inside of said object by said optical image fiber.

9. An apparatus as claimed in claim 8, said apparatus further comprising a second optical system for focusing the output of said optical image fiber onto an input portion of said ultrahigh speed light detecting means.

10. An apparatus as claimed in claim 1, wherein said light conducting means comprises an optical image fiber having one end thereof inserted into the inside of said object, said optical image fiber guiding said pulsed light to said inside and transmitting an image of said flux of reflected light pulses from inside said object to said ultrahigh speed light detecting means.

11. An apparatus as claimed in claim 10, said apparatus further comprising an optical system for focusing the output of said optical image fiber onto an input portion of said ultrahigh speed light detecting means.

12. An apparatus as claimed in claim 1, wherein said ultrahigh speed light detecting means comprises a streak camera comprising a streak tube including a photocathode, a deflecting plate for deflecting photoelectrons from said photocathode and a phosphor screen for receiving said deflected photoelectrons and forming a streak image thereon.

13. An apparatus as claimed in claim 1, wherein said ultrahigh speed light detecting means comprises a photodetector means having a rise time on the order of several tens of picoseconds to several hundred picoseconds for receiving said one flux and converting said one flux into electric signals. amplifiers electrically connected to said photodetector for amplifying said electric signals;

and a high-speed voltage-waveform analyzer for analyzing respective voltage-waveforms of said electric signals from said amplifiers.

14. An apparatus as claimed in claim 13, wherein said photodetector means comprises an array of photodiodes.

15. An apparatus as claimed in claim 13, wherein said photodetector means comprises a micro-channel-plate having a multi-output type multi anode portion.

16. An apparatus as claimed in claim 1, wherein said ultrahigh speed light detecting means comprises a Kerr-shutter for passing said one flux from said object during the effectuation of said Kerr-shutter, an image pickup device having two-dimensional image pickup elements for detecting said one flux passed through said Kerr-shutter, and delaying means, disposed between said pulse light source and said Kerr-shutter, for delaying a light pulse from said pulse light source and supplying it to said Kerr-shutter as a pump light, said Kerr-shutter being driven by irradiation from said pump light.

17. An apparatus as claimed in claim 1, wherein said ultrahigh speed light detecting means comprises a second harmonic generator for receiving said one flux from said object and generating a second harmonic of said one flux;

a photomultiplier tube (PMT) for detecting said second harmonic from said second harmonic generator; and

delaying means, disposed between said pulse light source and said harmonic generator, for delaying a light pulse from said pulse light source and supplying it to said second harmonic generator, the intensity of said second harmonic depending on the extent of the superimposition of said one flux and said delayed light pulse from said pulse light source.