Essential Skills for Optical Design - the fundamental principles and practices of lens design.

The aim of this "hands-on" course is to provide you with an understanding of why different lenses, such as telescope objectives, eyepieces, microscope objectives and photographic objectives take such different forms.

Successful lens design depends on two things: a deep understanding of the fundamental principles .... and years of practice. This course is designed to set you onto this road to success. It covers a number of subjects fundamental to lens design such as paraxial and real raytracing, Seidel (primary) aberration theory, total aberration theory and image analysis. Using these subjects we show how thin lens theory is used to develop a number of fundamental lens types.

The most efficient learning includes practice so our course includes considerable use of Zemax tutorial sessions to reinforce and illustrate concepts, to show how aberration plots are interpreted and to show why the performance of lens systems is limited by high order aberrations. You will return to work with the skills and knowledge to take your designs to the next level.

The course uses ZEMAX for examples on this course, but no prior knowledge of ZEMAX is required. Note this is not a software training course: attendees wanting to learn to use the ZEMAX software should attend our Optical Design Using ZEMAX course.

Essential Skills for Optical Design:

• The course starts by explaining how, using Snells's law, we can trace bundles of rays though optical systems, to obtain the typical data outputs and plots used by lens designers. Starting with simple singlet lenses you will study and learn how to interpret these output data.
• To go further we will need to review some basic geometrical optical quantities such as focal length, magnification, the Lagrange invariant, the important roles of the aperture stop and the entrance and exit pupils.
• Consideration of Fermat's Principle will allow us to define what we mean by geometrical wave front aberrations and to introduce the five characteristic monochromatic aberrations of axially symmetrical optical systems, namely spherical aberration, coma, astigmatism, field curvature and distortion.
• You will learn how estimates of the amounts of these aberrations can be derived from simple paraxial ray data. These estimates, known as Seidel sums, are vital to your understanding of how optical systems work.
• The variation of the refractive index of optical glass with wavelength leads to chromatic aberrations that also must be corrected.
• Knowing when a lens system is good enough for its application is crucial and you will learn how to use different image quality assessment techniques such as spot size, Strehl ratio and MTF.
• By considering a multi-element optical system in terms of simple "thin-lenses" you will be able to understand what each component is meant to do and follow this happening as Zemax, using accurate ray tracing, optimises the design.
• Much of the professional discussion between lens designers is based on this concept of systems of thin lenses.
• Using the Zemax program you will be led through a series of lens designs of increasing complexity as we require the correction of more or different aberrations.
• The examples we will show you have been carefully chosen to give you a solid foundation on which to build your future work. They include:
  • The singlet lens and its application in beam expanders, collimators, field lenses and simple eyepieces.
  • The achromatic doublet and its application in telescopes and microscopes, Petzval lenses and telephoto lenses.
  • The Cooke triplet, the Tessar and basic wide-field lenses.
  • The ubiquitous double Gauss lens.
• The course will emphasise the practical aspects of lens design, such as avoiding the use of expensive optical materials and making lens elements of suitable thickness to avoid manufacturing problems.
• You will be able to use your optical design computer package more effectively and with greater confidence now that you understand and can apply basic optical design theory.
  

Timetable

Registration Form

Course Instructors

Eddie Judd is Technical Director of Davin Optronics.

Professor Robin Smith formerly of Imperial College, London