Gain properties of a conical horn in the optical region

Martirosyan, V. A.; Muzhikyan, P. H.

doi:10.1364/ao.425193

Cited by 3 publications

(5 citation statements)

References 16 publications

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“…As shown in Ref. 19, the angle of view of the horn at full width at half maximum (FWHM) is approximately equal to its apex angle 2φ. Thus, using a horn instead of a lens expands the field of view of the detection system with a focusing element and sensor.…”

Section: Methodsmentioning

confidence: 98%

“…To analyze methods for focusing thermal waves from relatively hot objects, the characteristics of conical horns are studied in the geometrical optics approximation. 19 For our purpose, this type of radiation concentrator (when incident beam energy is collected at the horn's output window) is preferred because specific differences between focusing lenses and conical horns have been indicated. In Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The optimal length for given φ can be defined from equation (12) in Ref. 19: l≈d02 tan φ(cos φsin φ−1),where d0 is the diameter of the output window. With this length, the horn gain g (for normal incidence of radiation) is determined using the ratio of radiation intensity on the input πdi2/4 (where di is the diameter) and output πd02/4 windows from equation (11) in Ref.…”

Section: Methodsmentioning

confidence: 99%

“…With this length, the horn gain g (for normal incidence of radiation) is determined using the ratio of radiation intensity on the input πdi2/4 (where di is the diameter) and output πd02/4 windows from equation (11) in Ref. 19: g=di2d02=cot2 φ.…”

Section: Methodsmentioning

confidence: 99%

“…18. The gain characteristics of the conical horn depending on its geometric form and the reflection coefficient of its inner surface are studied 19 in the optical range. Implementation of visible object tracking with non-imaging methods allowed us to develop and test a human detection technique in the thermal infrared region.…”

Section: Introductionmentioning

confidence: 99%

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Distant human detection in the thermal infrared region

Martirosyan,

Kostanyan,

Martirosyan

et al. 2024

Opt. Eng.

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Human detection equipment that operates indoors and outdoors plays an important role in modern security applications. We describe a nonconventional system to detect thermal infrared radiation from relatively hot objects using a conical horn and a non-matrix thermal infrared sensor. It is shown that using a conical horn as a radiation concentrator in a recording device is preferable to a focusing lens due to specific differences between them. A software program in Python is developed to permanently observe the thermal infrared radiation from surroundings. The obtained results indicate an inverse relationship between the angle of view and the gain level of conical horns. It is experimentally shown that the horn-sensor pair detects humans at long distances (up to 40 m) with a relatively narrow angle of view of 16 deg. On the other hand, using a conical horn with a wider apex angle increases the angle of view of the recording system up to 30 deg but reduces the detection range. The device with four coupled horn-sensor pairs extends the horizontal angle of view to 90 deg. The developed technique can operate day and night, indoors (including observation of long corridors), and outdoors to monitor humans and vehicles or to prevent fires. The recording system can be applied together with other security equipment as an initial alarm system that triggers video monitoring and night vision devices.

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