In optical design with freeform surfaces descriptions of the surfaces are needed that use only few parameters and are suitable for optimisation. Depending on the merit function – spot size or wavefront error – and the position of the surface in the system, different surface types can yield different optimisation performance. It has been demonstrated by G. Forbes that slope orthogonal polynomials are an advantageous freeform description. From literature on Gaussian moments it is known that this can be achieved using differences of Zernike polynomials, which are easy to compute and implement with recent algorithms. We will demonstrate the benefits of Zernike polynomials with optimisation examples. Furthermore we present an orthogonal surface representation on a rectangular aperture based on Chebyshev polynomials. This description is very convenient when the aperture has a very high aspect ratio, or when designing a system with a rectangular pupil.
Today’s high brilliance Laser sources cause huge thermal effects on optical components, affecting process stability.
This paper shows the holistic approach to the improvement of objective lenses to minimum thermal effects as focus shift.
A new approach to the transient simulation of thermal behavior, starting with FEM Analysis, analytical description of
surface deformation and refraction index distribution resulting in transient plot of image quality changes by optics design
simulation. Optics material selection and characterization of bulk material, surface and coating by newly developed
measurement techniques is shown. The optimum setting of opto-mechanical design, material selection, surface finish and
coating allows to produce lenses with focus shift by 0,05times the Rayleigh range @1064nm, 4kW multimode at
Jenoptik Laser, Optik, Systeme GmbH has developed a new mounting technology for optical elements. It is free of any
glue or other organic material whereby it is excellently appropriate to the use for DUV Systems, especially if high intensity occurs as it is to be found in illuminating systems. The new technology has been successfully applied in high quality lenses e.g. in a high NA inspection lens @266nm and several ultra high quality imaging systems @193nm. The so called Clamp Mount Technology is characterized by high accuracy and stability under environmental influence such as shock, vibration or thermal effects. There is no limitation in use with any optical material e.g. fused silica or calcium fluoride. The lens cells are routinely optimized by finite element method. Thus in advance clamp force is optimized having regard to deformation of optical surfaces, lens shape, lens weight, gravity and shock load. Additionally stress induced polarization effects are predictable. The FEM simulation results can be transferred to optical design tools which are used for lens design as much as for comparing design data with experimental results.