Optical design consultancy based in Japan
Lens design examples overview
The design examples illustrate the practical performace of his design methodology.
- Glass cost control is applied to a night scope objective.
- Sensitivity control is applied to a night scope objective, a compact zoom lens, and an Arf lithography lens.
- Prototyping of zoom lens is applied to a compact zoom lens.
- Design with aspheric surfaces is shown for a compact zoom lens and an Arf lithography lens.
- Ghost control is applied to a sensor lens.
Glass cost control for night scope objective
For the control of the chromatic aberration over a wide range of wavelength, abnormal dispersion glasses are effective. With the accurate glass model including the abnormal dispersion, the good combination of glasses is automatically found by the global optimization.
When the glasses are used as design parameters, the fictitious glasses tend to reach the boundary of the allowed region. Such a solution is not practical because glasses are very expensive at the boundary. The glass cost can be controlled as a design target. With this function the low cost glasses are effectively selected.
Design conditions: F1.4, field angle 6deg., f =100mm, total lens length 200mm, wavelength 450-950nm.
Calculation time: global optimization 48 min. (40 solutions), MTF optimization 9 min. (28 solutions).
Sensitivity control for rear projection lens
The sensitivity to manufacturing errors is important for the practical design. The sensitivity can be controlled as a design target. In this example the sensitivity to tilt is controlled. The sensitivity of each surface is shown on the chart. The tolerances for the design with the sensivitity control can be greatly relaxed.
Design conditions: F2.5, object height 300mm, image height 7.15mm, object distance 450mm, total lens length 90mm, wavelength 450-630nm.
Calculation time: global optimization 16 min. (100 solutions), MTF optimization 3 min. (17 solutions).
Compact zoom lens with aspherics
The global optimization with escape function is also effective for the zoom lens and aspherics. The target of this example is the design of a high quality compact zoom lens with the zoom range of f =28-103mm.For this problem 2 group zoom system is used and 2 aspherical elements are used. The starting point of the optimization was generated by the prototyping method. In this design the position of aspherical elements is extended to continuous variables and the best position of aspherical elements is determined by the global optimization. The sensitivity to surface irregularity of aspheric surfaces is controlled.
Design conditions: f =28-103mm, F3.7-9.1, length from 1st surface to image surface <103mm, wavelength 486-656nm.
Calculation time: global optimization 63 min. (100 solutions), MTF optimization 8 min. (15 solutions).
Sensitivity control for ArF lithography lens
The sensitivity control is also effective for high NA lenses. Many aspheric surfaces are used for modern lithography lenses. In this design the position of aspheric surfaces is extended to continuous variables and the best position of aspheric surfaces is determined by the global optimization.
Design conditions: NA=0.85, image circle diameter 27.7mm, magnification -1/4, total track 1250mm, wave length 193.306nm.Calculation time: global optimization 1183 min. (10 solutions), MTF optimization 53 min. (3 solutions).
Ghost control for sensor lens
The ghost image is detected systematic in a very short time. The problematic ghost image is controlled during the optimization.
Design conditions: FNO=2.0, tangent of the field of view =0.25, focal length 50mm, overall length <50mm, wavelength 486-656nm.