Marco Hanft

Challenges of designing a zoom lens for planetarium projection

The optical design of zoom lenses for projection applications is a task which has to take many different aspects into consideration. The optical designer has to achieve a demanding specification with respect to monochromatic and polychromatic aberrations across a significant magnification range. Besides the requirements on image quality there are usually numerous constraints deriving from fixed mechanical interfaces that already have an impact in the very early design stages of the paraxial and monochromatic design. It has been proven essential to also include cost targets in the figure of merit during the design work. This paper will outline a systematic process for projection zoom lenses design. A solid specification of the design task in terms of magnification range, image quality therein, mechanical and cost requirements is necessary as starting point. Paraxial considerations are helpful to gain insight into the design problem and choose the appropriate zoom design type for further design work. Intermediate designs, which are only monochromatically corrected, proofed invaluable while considering mechanical design requirements. As soon the basic design requirements are fulfilled it makes sense to correct chromatic aberrations. Outstanding color correction requires extensive use of expensive glasses for secondary color correction. In order to find an ideal compromise between potential cost of an optical design and image quality achieved therewith, we employ tools to identify cost drivers as well as tools to simulate the perceived imaging performance. Together these tools also enable us to efficiently discuss specifications that drive cost without aiding perceived image quality.

Tolerance analysis of optical systems using the Nijboer-Zernike approach

Optical systems are designed to provide a specific functionality. However, a built optical system shows some deviations from the nominal performance caused by the manufacturing process. This tutorial will demonstrate the tolerancing process using Nijboer-Zernike polynomials as an expression of wave front aberrations. Nijboer-Zernike polynomials are a special form of well-known circle polynomials developed by Zernike. They are orthogonal and have an automatic balancing of aberrations of various orders. The degradation of the Strehl Ratio can be estimated very easily for every single aberration using the value of the specific coefficient. This property is very beneficial for the definition of a tolerance budget.

Zoom lens design for projection optics

The optical design of zoom lenses for projection applications is a task which has to take many different aspects into consideration. The optical designer has to achieve a demanding specification with respect to monochromatic and polychromatic aberrations across a significant magnification range. Besides the requirements on image quality there are usually numerous constraints deriving from fixed mechanical interfaces that already have an impact in the very early design stages of the paraxial and monochromatic design. It has been proven essential to also include cost targets in the figure of merit during the design work. This paper will outline a systematic process for projection zoom lenses design. A solid specification of the design task in terms of magnification range, image quality therein, mechanical and cost requirements is necessary as starting point. Paraxial considerations are helpful to gain insight into the design problem and choose the appropriate zoom design type for further design work. Intermediate designs, which are only monochromatically corrected, proofed invaluable while considering mechanical design requirements. As soon the basic design requirements are fulfilled it makes sense to correct chromatic aberrations. Outstanding color correction requires extensive use of expensive glasses for secondary color correction. In order to find an ideal compromise between potential cost of an optical design and image quality achieved therewith, we employ tools to identify cost drivers as well as tools to simulate the perceived imaging performance. Together these tools also enable us to efficiently discuss specifications that drive cost without aiding perceived image quality.