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A harmonic diffractive element (HDE) is first successfully introduced to the athermal system of infrared dual band in this paper. In this system, there are only three lens and two materials, silicon and germanium. When the temperature ranges from 70℃ to 100℃ in the dual band, it can simultaneously accomplish the rectification of the longitudinal aberration in the big field of view, as well as the wave front aberration less than 1/4 wavelength. Modulation transfer function of dual band approaches or attains the diffraction limit. The calculation results show that the spec-tral properties of the HDE are between refractive and dif-fractive elements, so we can design a simple dual-band and athermal optical system by selecting the thickness and cen-tral wavelength of the HDE exactly. Compared with a con-ventional refractive optical system, this system not only re-duces the demand for high technical levels, but also has a compact structure, few elements, a high transmittance better aberrations performances and athermal character. At the same time, the use of the HDE also offers a new element for the infrared optics design.
A harmonic diffractive element (HDE) is first successfully introduced to the athermal system of infrared dual band in this paper. There are only three lenses and two materials, silicon and germanium. When the temperature ranges from 70 ° C to 100 ° C in the dual band, it can include accomplish the rectification of the longitudinal aberration in the big field of view, as well as the wave front aberration less than 1/4 wavelength. Modulation transfer function of dual band approaches or attains the diffraction limit. calculation results show that the spec-tral properties of the HDE are between refractive and dif-fractive elements, so we can design a simple dual-band and athermal optical system by selecting the thickness and cen-tral wavelength of the HDE exactly. a con -ventional refractive optical system, this system not only re-duces the demand for high technical levels, but also has a compact structure, few elements, a high transmittance better aberr ations performances and athermal character. At the same time, the use of the HDE also offers a new element for the infrared optics design.