Underwater laser imaging apparatus

• US 6,115,511 A
• Filed: 10/27/1997
• Issued: 09/05/2000
• Est. Priority Date: 10/28/1996
• Status: Expired due to Fees

• Current Assignee: Director-General Hokuriku Regional Development Bureau Ministry of Land Infrastructure and Transport, Ishikawajima-Harima Heavy Industries Company Limited
• Original Assignee: Director General of Port Harbour Research Institute Ministry of Transport, Director General of The 1TH District Port Construction Bureau Ministry of Transport, Ishikawajima-Harima Heavy Industries Company Limited
• Inventors: Tanaka, Toshinari, Ishida, Shiro, Satoh, Eiji, Sakai, Hiroshi, Takahashi, Yoshiaki, Saito, Toshitaka, Hirose, Kenzi, Asatsuma, Harukazu, Igarashi, Hirotoshi, Akizono, Junichi
• Primary Examiner(s): Johns, Andrew W.
• Application Number:
  US08/958,564
• Time in Patent Office: 1,044 Days
• Field of Search: 382/100, 382/312, 382/318, 382/321, 348/81, 250/573, 250/574, 356/436, 359/141, 372/35
• US Class Current: 382/312
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4815 using multiple transmitters

Abstract

A simulation method for imaging of an underwater object is performed by simulating the object with a test panel having several strips of different brightness, and irradiating the test panel with a pulsed laser beam having three primary colors. From the reflected beam pulses, contrast values of the test stripes are computed for reflected pulses of each color in relation to the turbidity and visibility distance. The method may be used in conjunction with an imaging apparatus having a laser generation device which produces three primary colors of three different wavelengths; a laser beam detection device to receive the reflected beam pulses of respective primary colors, to determine intensities of the reflected beam pulses of respective primary colors, and to output three primary color signals to an image monitoring device. The imaging system may also be arranged so that a laser irradiation device, a laser beam detection device and an image monitoring device are all placed underwater in a submersible vessel with appropriate provisions for hydrostatic pressure and unmanned operation.

Claims

1. A laser imaging apparatus for observing an underwater object disposed in a beam transmission medium comprising:

a laser generation device for generating three primary colors of visible light, each color comprised by a pulsed laser beam having a respective wavelength, and irradiating pulsed laser beams towards said underwater object;

a laser beam detection device for separating reflected beam pulses reflecting from said underwater object into a wavelength component representing each of said three primary colors, determining an intensity value for each of three wavelength components and outputting three primary color signals according to intensity values; and

an imaging device for forming an image of said underwater object based on said three primary color signals.

2. An apparatus according to claim 1, wherein said beam transmission medium is water.

3. An apparatus according to claim 2, wherein said laser generation device and said laser beam detection device are disposed in an unmanned submersible vessel.

4. An underwater laser imaging apparatus comprising:

a laser irradiation device disposed underwater for irradiating an underwater object with a pulsed laser beam;

a laser generation device disposed underwater for generating a plurality of colors of light in said pulsed laser beam;

a laser beam detection device for receiving reflected beam pulses reflected from said underwater object; and

an image processing device for forming images of said underwater object according to output signals from said laser beam detection device.

5. An apparatus according to claim 4, wherein said laser irradiation device is provided with a cooling device utilizing surrounding water for cooling said laser generation device.