National Technical Reports Library

The National Technical Information Service acquires, indexes, abstracts, and archives the largest collection of U.S. government-sponsored technical reports in existence. The NTRL offers online, free and open access to these authenticated government technical reports. Technical reports and documents in its repository may be available online for free either from the issuing federal agency, the U.S. Government Publishing Office’s Federal Digital System website, or through search engines.

Details

Understanding Beam Alignment in a Coherent Lidar System.

N150017033

Publication Date	2015
Personal Author	Prasad, N. S.; Roychoudhari, C.
Page Count	7
Abstract	Optical beam alignment in a coherent lidar (or ladar) receiver system plays a critical role in optimizing its performance. Optical alignment in a coherent lidar system dictates the wavefront curvature (phase front) and Poynting vector) matching of the local oscillator beam with the incoming receiver beam on a detector. However, this alignment is often not easy to achieve and is rarely perfect. Furthermore, optical fibers are being increasingly used in coherent lidar system receivers for transporting radiation to achieve architectural elegance. Single mode fibers also require stringent mode matching for efficient light coupling. The detector response characteristics vary with the misalignment of the two pointing vectors. Misalignment can lead to increase in DC current. Also, a lens in front of the detector may exasperate phase front and Poynting vector mismatch. Non-Interaction of Waves, or the NIW property indicates the light beams do not interfere by themselves in the absence of detecting dipoles. In this paper, we will analyze the extent of misalignment on the detector specifications using pointing vectors of mixing beams in light of the NIW property.
Keywords	Optical radar Alignment Fiber optics Laser range finders Wave fronts Light beams Oscillators Detection
Source Agency	National Aeronautics and Space Administration
NTIS Subject Category	46C - Optics & Lasers 45 - Communication
Corporate Authors	National Aeronautics and Space Administration, Hampton, VA. Langley Research Center.
Supplemental Notes	Text in English.Presented at SPIE Optics and Photonics 2013, San Diego, CA, United States, 25-29 Aug. 2015.Distribution Note: Publicly available, Unlimited, Distribution as joint owner in the copyright. CASI.
Document Type	Conference Proceedings
NTIS Issue Number	201604

Understanding Beam Alignment in a Coherent Lidar System.

Understanding Beam Alignment in a Coherent Lidar System.
N150017033

Publication Date	2015
Personal Author	Prasad, N. S.; Roychoudhari, C.
Page Count	7
Abstract	Optical beam alignment in a coherent lidar (or ladar) receiver system plays a critical role in optimizing its performance. Optical alignment in a coherent lidar system dictates the wavefront curvature (phase front) and Poynting vector) matching of the local oscillator beam with the incoming receiver beam on a detector. However, this alignment is often not easy to achieve and is rarely perfect. Furthermore, optical fibers are being increasingly used in coherent lidar system receivers for transporting radiation to achieve architectural elegance. Single mode fibers also require stringent mode matching for efficient light coupling. The detector response characteristics vary with the misalignment of the two pointing vectors. Misalignment can lead to increase in DC current. Also, a lens in front of the detector may exasperate phase front and Poynting vector mismatch. Non-Interaction of Waves, or the NIW property indicates the light beams do not interfere by themselves in the absence of detecting dipoles. In this paper, we will analyze the extent of misalignment on the detector specifications using pointing vectors of mixing beams in light of the NIW property.
Keywords	Optical radar Alignment Fiber optics Laser range finders Wave fronts Light beams Oscillators Detection
Source Agency	National Aeronautics and Space Administration
NTIS Subject Category	46C - Optics & Lasers 45 - Communication
Corporate Authors	National Aeronautics and Space Administration, Hampton, VA. Langley Research Center.
Supplemental Notes	Text in English.Presented at SPIE Optics and Photonics 2013, San Diego, CA, United States, 25-29 Aug. 2015.Distribution Note: Publicly available, Unlimited, Distribution as joint owner in the copyright. CASI.
Document Type	Conference Proceedings
NTIS Issue Number	201604