I am building an integrating sphere from some aluminum hemispheres. They are not entirely spherical when put together. One is slightly flattened on each half. The other does not entirely complete the radius so it leads to a slightly elliptical shape ( about 51.5mm x 48.5mm dia).
Knowing what I do about integrating spheres, the concept is to be sure the light is evenly distributed on the walls of the sphere before absorption of the paint finally quenches the incoming light.
In the case of the flattening I would think that if the light lands such that it bounces between the two flattened surfaces, the distribution effect will be highly perturbed. In the case of the slightly out-of-round sphere the result is not so obvious.
I think the only "easy" solution is a ray-trace which I don't have access to. I looked thru a lot of literature but I don't see this issue addressed. Even with a commercial sphere I am sure there is some degree of "out-of-round" nature and there probably is some disturbance to the result.
I am just curious if anyone has found any information on this or has an educated guess on the degree of sphericity required for a reasonable sphere.
Thanks
Fritz
I don't expect any big issues from such a minor shape deviaton. It is more important to have the right paint and spend some effort on calibration.
A colleague of mine once invetend the "Ulbricht shoebox" and it worked in a satisfactory manner too.
Henning
Sorry for the late reply- apparently Researchgate does not send alerts via email.
At any rate thank you for your input.
Spectrolon and similar products are very expensive so I will be using Barium Sulfate mixed with paint having and LRV of around 92.
Fortunately the work I am doing will be in making comparisons and approximations so having a sphere less quality than a commercial one will probably be OK.
cheers
Fritz
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