Target detection performance of infrared spectrum with diffractive optical system

Kai Zhou; Daojing Li; Yefei Wang; Yuan Yao; Ming Qiao

doi:10.3788/IRLA20200371

Journals >Infrared and Laser Engineering >Volume 50 >Issue 8 >Page 20200371 > Article

Infrared and Laser Engineering
Vol. 50, Issue 8, 20200371 (2021)

Target detection performance of infrared spectrum with diffractive optical system

Kai Zhou^1、2, Daojing Li^1、*, Yefei Wang³, Yuan Yao³, and Ming Qiao¹

Author Affiliations

¹National Key Laboratory of Microwave Imaging Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China

²University of Chinese Academy of Sciences, Beijing 100049, China

³Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China

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DOI: 10.3788/IRLA20200371 Cite this Article

Kai Zhou, Daojing Li, Yefei Wang, Yuan Yao, Ming Qiao. Target detection performance of infrared spectrum with diffractive optical system[J]. Infrared and Laser Engineering, 2021, 50(8): 20200371 Copy Citation Text

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$Optical path diagram of infrared camera system based on diffractive optical system$

Fig. 1. Optical path diagram of infrared camera system based on diffractive optical system

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Graph of relative radiant exitance function of black-body when takes different ranges. (a) takes entire range; (b) takes 2.4×103-3.6×103μm·K ; (c) takes 0-1.5×103μm·K取不同范围时黑体相对辐出度函数图。(a) 取全部范围；(b) 取2.4×103~3.6×103μm·K；(c) 取

Fig. 2. Graph of relative radiant exitance function of black-body when takes different ranges. (a) takes entire range; (b) takes 2.4×10³-3.6×10³μm·K ; (c) takes 0-1.5×10³μm·K 取不同范围时黑体相对辐出度函数图。(a) 取全部范围；(b) 取2.4×10³~3.6×10³μm·K；(c) 取

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Fig. 3. Same spectral curve of radiance at target/background temperature difference of 1 K

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Fig. 4. Differrent spectral curve of radiance at target background temperature difference of 1 K

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Fig. 5. Principle block diagram of the laser local oscillator unit detector

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Parameters	Value	Parameters	Value
Conversion factor $K$	0.7	F number of optical systems	1
Grass background temperature in Summer ${T_B}$	303 K	Detector peak wavelength ${\lambda _p}$	$10.8\;{\text{μm}}$
First radiation constant ${c_1}$	$3.741\;5 \times {10^8}\;{\rm{W}} \cdot \;{{\text{μm}}^4} \cdot \;{{\rm{m}}^2}$	Second radiation constant ${c_2}$	$1.438\;8 \times {10^4}{\text{μm}} \cdot \;{\rm{K}}$
Optical system transmittance during testing ${\eta _{0t}}$	0.6	Background emissivity	0.93
Noise equivalent temperature difference $NETD$	$40 \times {10^{ - 3}}\;{\rm{K}}$	Integration time during testing ${t_{{\rm{int}} 1}}$	$34.56 \times {10^{ - 6}}\;{\rm{s}}$
Detector pixel area ${A_d}$	${\left( {14 \times {{10}^{ - 6}}} \right)^2} \times {10^4}\;{\rm{c}}{{\rm{m}}^2}$	Detector specific detectivity ${D^*}$	$5.{\rm{4}} \times {10^{10}}\;{\rm{cm}} \cdot \;{\rm{H}}{{\rm{z}}^{1/2}} \cdot \;{{\rm{W}}^{ - 1}}$

Table 1. Relevant parameters for calculating

\begin{document}${D^*}$\end{document}

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Parameters	Value	Parameters	Value
Signal extraction factor $\delta $	0.707	Number of pixels occupied by the vehicle target on the focal plane ${N_t}$	1
Atmospheric transmittance ${\tau _a}$	0.75	Optical system aperture ${D_0}$	100 mm
Optical system transmittance ${\eta _0}$	0.6	Optical system entrance pupil area ${A_0}$	$79 \times {10^{ - 4}}\;{{\rm{m}}^2}$
Integration time in actual work ${t_{{\rm{int}} 2}}$	$10 \times {10^{ - 3}}\;{\rm{s}}$	Target effective radiation area ${A_t}$	$4 \times {10^4}\;{\rm{c}}{{\rm{m}}^2}$
Background surface temperature	303 K	Target surface temperature	304/306/308 K
Detection range R	15 km	Detector specific detectivity ${D^*}$	$1.4 \times {10^9}\;{\rm{cm} } \cdot \;{\rm{H} }{ {\rm{z} }^{1/2} } \cdot \;{ {\rm{W} }^{ - 1} }$

Table 2. System parameters

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Parameters	Value
Target/background emissivity	0.93/0.93
Target/background spectral range	8-12 μm
Target radiance	$\left( {3.82/3.94/4.06} \right) \times {\rm{1}}{{\rm{0}}^{{\rm{ - 3}}}}\;{\rm{W}} \cdot {\rm{c}}{{\rm{m}}^{ - 2}} \cdot {\rm{s}}{{\rm{r}}^{ - 1}}$
Background radiance	$3.75 \times {\rm{1}}{{\rm{0}}^{{\rm{ - 3}}}}\;{\rm{W}} \cdot {\rm{c}}{{\rm{m}}^{ - 2}} \cdot {\rm{s}}{{\rm{r}}^{ - 1}}$
SNR of infrared detection with traditional optical system	3.9/11.9/20
SNR of infrared detection with diffractive optical system	0.19/0.55/0.92

Table 3. Infrared detection SNR under different optical systems when the spectral characteristics of target/ background are same

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Parameters	Value
Target/background emissivity	0.93/0.2
Target/background spectral range	10.4-11 μm/8-12 μm
Target radiance	$\left( {5.75/5.92/6.1} \right) \times {\rm{1}}{{\rm{0}}^{{\rm{ - 4}}}}\;{\rm{W}} \cdot {\rm{c}}{{\rm{m}}^{ - 2}} \cdot {\rm{s}}{{\rm{r}}^{ - 1}}$
Background radiance	$8.08 \times {\rm{1}}{{\rm{0}}^{{\rm{ - 4}}}}\;{\rm{W}} \cdot {\rm{c}}{{\rm{m}}^{ - 2}} \cdot {\rm{s}}{{\rm{r}}^{ - 1}}$
SNR of infrared detection with traditional optical system	15.2/14/12.9
SNR of infrared detection with diffractive optical system	9.7/10.1/10.5

Table 4. Infrared detection SNR under different optical systems when the spectral characteristics of target/background are different

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	Signal time width	Equivalent noise power
Electronics system	0.25 ns	$1.6 \times {10^{ - 11}}\;{\rm{W}}$
Laser system	0.25 ns	$7.3 \times {10^{ - 11}}\;{\rm{W}}$
Laser system	10 ms	$1.8 \times {10^{ - 16}}\;{\rm{W}}$
Infrared system	10 ms	$6.8 \times {10^{ - 12}}\;{\rm{W}}$

Table 5. Equivalent noise power in different systems

Kai Zhou, Daojing Li, Yefei Wang, Yuan Yao, Ming Qiao. Target detection performance of infrared spectrum with diffractive optical system[J]. Infrared and Laser Engineering, 2021, 50(8): 20200371

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