Quantifying the effect of the Temperature Variable on Optical Anisotropy of Line Spread Function at Image plane

It is well known that the variable of temperature degree will effect on the characteristics of any optical component especial lenses and mirrors, because this thermal variable will affect on thermal expansion of the optical component material, we can say (refractive index (n) of the material), Of course this effect will transfer to the ray tracing throw the optical components and which effect on the properties of the spot diagram of image forming. (Even the temperature is increasing or decreasing). When the rays intersect with the image plane, there will be a spot (the spot is intersected between two or more rays that intersect the image plane), the spot distribution will represent the image of the object. This is called a spot diagram. The spot diagram has an important property which are the sizes of spots and type of distribution. So, the thermal effect will appear in these properties of the spot diagram. The main properties of the lens that been affected by thermal is curvature of the surface (R), thickness, object and image planes position (the distances of object & image from the lens center, (S ,S’) are variables will make changing in the values of focal length of the lens (that means defocus) appear