Cylindrical quasi-cavity waveguide for static wide angle pattern projection

An intruder detection and discrimination sensor with improved optical design is developed using lasers of different wavelength to demonstrate the concept of discrimination over a distance of 6m. A distinctive feature of optics is used to provide additional transverse laser beam scanning. The sample objects used to demonstrate the concept of discrimination over a distance of 6m are leaf, bark, black fabric, PVC, wood and camouflage material. A camouflage material is chosen to illustrate the discrimination capability of the sensor. The sensor utilizes a five-wavelength laser combination module, which sequentially emits identically-polarized laser light beams along one optical path. A cylindrical quasi-optical cavity with improved optical design generates multiple laser light beams for each laser. The intensities of the reflected light beams from the different spots are detected using a high speed area scan image sensor. Object discrimination and detection is based on analyzing the Gaussian profile of reflected light at the different wavelengths. The discrimination between selected objects is accomplished by calculating four different slopes from the objects' reflectance spectra at the wavelengths 473nm, 532nm, 635nm, 670nm and 785nm. Furthermore, the camouflage material, which has complex patterns within a single sample, is also detected and discriminated over a 6m range by scanning the laser beam spots along the transverse direction.

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“…A cylindrical quasi-optical cavity, fabricated using BK-7 glass medium [7], was devised to produce multiple laser spots, as shown in Figure 3.…”

Section: Cylindrical Quasi-optical Cavitymentioning

confidence: 99%

Multi-wavelength laser sensor for intruder detection and discrimination

Venkataraayan

Askraba

Alameh

et al. 2012

Optics and Lasers in Engineering

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“…A custom-made optical cavity was used to resolve the problem from diffracting the laser beams of different wavelengths onto a spot array [5,6]. This cavity was made of BK-7 glass with 45° curvature and inner and outer interface radii of R 1 and R 2 , respectively.…”

Section: Fig 4 Optical Cavity Structurementioning

confidence: 99%

Multi-wavelength laser scanning architecture for object discrimination

Venkataraayan

Askraba

Alameh

et al. 2010

7th International Symposium on High-Capacity Optical Networks and Enabling Technologies

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A novel method for identifying and discriminating various objects using five different lasers is described. This method uses a laser combination module that allows five laser diodes of different wavelengths to sequentially emit identically polarized light beams through a common aperture, along one optical path. Each laser beam enters a custom-made curved optical cavity for multi-beam spot generation through internal partial beam reflection. The intensity of the reflected light beams from each spot is detected by a high-speed area scan image sensor. Object discrimination based on analyzing the Gaussian profile of reflected laser light at distinguishing wavelengths is demonstrated.

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“…2(a) illustrates principal rays of the novel triangulation system incorporating the quasi-cylindrical optical cavity. Adopting the linear algebraic ray tracing method from [7], cavity interfaces and rays are predicted using equations for circles and straight lines, respectively. Fig.…”

Section: Active Triangulation Geometry Fundamentalsmentioning

confidence: 99%

A novel wide angle laser triangulation method for obstacle detection

Sahba¹,

Alameh²,

Smith³

2008

Proceedings of SPIE

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Indoor active triangulation to laser spots generated by quasi-cylindrical cavity is demonstrated. Principal ray trajectory is modeled using a system of linear equations and fundamental ray geometry. Each ray's unique outgoing angle and baseline is calculated and used to derive the range to the corresponding spot. Above 98% accuracy is achieved over an approximate range of 5m, demonstrating a novel motionless laser scanning technique with a wide scanned angle and no moving parts.

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Cylindrical quasi-cavity waveguide for static wide angle pattern projection

Cited by 8 publications

References 8 publications

Multi-wavelength laser sensor for intruder detection and discrimination

Multi-wavelength laser sensor for intruder detection and discrimination

Multi-wavelength laser scanning architecture for object discrimination

A novel wide angle laser triangulation method for obstacle detection

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