内挿法によるTransfer Functionの近似精度
1964 年 33 巻 6 号 p. 395-400
詳細
1964 年 33 巻 6 号 p. 395-400
By the development of electronic computer, the use of spot diagram for evaluation of optical image has become practical, but the computation involves the time-consuming and troublesome skew ray tracing, for which simplification, Herzberger's interpolation method is applied and the transfer function is obtained by using a lens of F/2.5, f=75 mm as
R(s, t)=1/N_??_ exp[-2πi(sΔxi+tΔyi)]
With this transfer function, the interpolation method is compared with the exact skew ray tracing method in regard to the accuracy. The relation found between the number of sampling points that were used to determine the coefficients of the interpolation formula and the accuracy of the coefficients or the transfer function shows that the skew ray tracing of 7 sampling points for 0° incident angle and 12 sampling points for 15° incident angle are sufficient for the accuracy. Good results are obtained on lenses of F/4 and lower apertures but not on lenses of higher apertures such as F/2.5.
