Design example for the use of hybrid optical elements in the infrared

Area of Science:

• Optical Engineering
• Infrared Optics

Background:

• The Petzval objective is a common design for IR cameras, but its field coverage is limited.
• High-aperture IR systems require effective aberration correction.

Purpose of the Study:

• To enhance the performance of Petzval objectives for IR camera systems.
• To achieve broadband color correction and correct aberrations using a novel lens design.

Main Methods:

• Utilized a hybrid aspheric/diffractive front lens element.
• Employed diamond turning for simultaneous generation of diffractive and aspheric surfaces.
• Integrated the diffractive profile on the rear surface of the front element for environmental protection.

Main Results:

• Achieved broadband color correction in the 3-5 µm or 8-12 µm regions with a single lens material.
• Successfully corrected spherical and chromatic aberrations.
• Demonstrated the feasibility of integrating complex optical surfaces using high-precision manufacturing.

Conclusions:

• The hybrid aspheric/diffractive lens design significantly improves IR camera system performance.
• This approach offers a compact and effective solution for aberration correction in IR optics.
• The use of Germanium as a lens material is suitable for long-wavelength IR applications, with considerations for high-temperature environments.