Applications of a laser radar system with depth accuracy down to 0.2 mm for high accuracy 3-D imaging are described.
The system is based on a green pulsed laser triggering a picosecond ICCD camera with data recording of only a few
seconds. The submillimeter accuracy gradually degrades at ranges above a few hundred meters due to turbulence,
vibrations, etc. As a specific example, we show 3-D accuracy for surface tile inspection of a miniature space shuttle and
the resolution of cracks and defects is demonstrated, which is relevant for the planned laser radar inspections from the
space shuttle boom and the longer range survey from the International Space Station. By coupling the laser light through
a Raman fiber we also demonstrate multispectral 3-D imaging.
KEYWORDS: Cameras, Pulsed laser operation, 3D image processing, LIDAR, 3D acquisition, Signal to noise ratio, 3D vision, Imaging systems, Water, Optical imaging
New 3-D optical underwater images are presented. The 3-D images are recorded in fresh water and brackish sea water (salinity 15), at 4- to 5-m range. For the first time, underwater 3-D images are computed by our new algorithm, which applies the method of weighted averages on a sequence of 2-D images. It is proposed that 3-D gated viewing images can be recorded at any contrast level between 0 and 100%. A novel and dynamic way of measuring the depth of gating is presented. A novel correction for gated viewing 3-D imaging is presented. For the first time, an exact solution of the depth of gating is proposed for a rectangular laser pulse.
Results from our fast and high accuracy 3-D laser radar are given at distances up to 500 m. The system is based on gated viewing with range accuracy below 1 mm under optimal circumstances. It consists of a high sensitivity, fast, intensified CCD camera, and an Nd:YAG passively Q-switched 32.4 kHz pulsed green laser at 532 nm. The CCD has 752×582 pixels. Camera shutter and delay steps are controlled in steps of 100 ps. Each laser pulse triggers the camera delay and shutter. A 3-D image is constructed from a sequence of 50-100 2-D reflectivity images, where each frame integrates ~700 laser pulses on the CCD. In 50 Hz video mode we record a 2-D sequence in a second and process a 3-D image in a few seconds. We compare 3-D images at short to long distances and quantify the degree of person identification in 3-D. Turbulence, vibrations and system errors are found to limit a successful PID to distances shorter than ~500m for our prototype system.
KEYWORDS: Cameras, 3D image processing, Pulsed laser operation, LIDAR, 3D modeling, Picosecond phenomena, Reflectivity, Signal to noise ratio, 3D vision, 3D acquisition
We have developed a mono-static staring 3-D laser radar based on gated viewing with range accuracy below 1 mm at 10 m and 1 cm at 100 m. We use a high sensitivity, fast, intensified CCD camera, and a Nd:YAG passively Q-switched 32.4 kHz pulsed green laser at 532 nm. The CCD has 752×582 pixels. Camera shutter is controlled in steps of 100 ps. Camera delay is controlled in step of 100 ps. Each laser pulse triggers the camera delay and shutter. A 3-D image is constructed from a sequence of 50-100 2-D reflectivity images, where each frame integrates ~700 laser pulses on the CCD. In 50 Hz video mode we record a 2-D sequence in a second and process a 3-D image in few seconds. We compare 3-D images with a system performance model.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.