sub-diameter Archives -

Mirror 610 F3 meniscus

May 8, 2026Massimo MarconiConstructive Reportmeniscus, parabolic mirror, sub diameter

The manufacturing phases of a meniscus parabolic mirror 610 mm in diameter and 20 mm thick, focus 1770 mm with focal ratio of F3.

How to read the fringes of Newton and correct the convex mirror.

Dec 5, 2016Massimo MarconiSecondary mirrorNewton's fringes, sub diameter

As we have seen in this article, a convex secondary mirror can not be tested directly in general (*) . One of the methods is used to refer to a concave mirror which has the same shape of the surface that we want to get on the convex mirror. By overlaying the two mirrors, the analysis of the interference fringes by means of

how to parabolize a low focal ratio mirror ( F2-F4 ) - Part Three

Nov 19, 2015Massimo Marconi2 CommentsParabolizzazioneparabolic mirror, sub diameter

Now let's see how to develop a procedure that takes account of the problems highlighted in the article II, that is how to generate the project by means of a parabola working as regular as possible, with particular attention to the control of the figure during the intermediate stages of processing. THE METHOD “CUSTOM” The name only want to indicate they are not

how to parabolize a low focal ratio mirror ( F2-F4 ) - second part

Sep 26, 2015Massimo MarconiParabolizzazioneparabolic mirror, sub diameter

Is’ useful at this point, a recall on processing techniques with the tools at the sub-diameter, in particular how it is possible to increase the curvature of one or more zones. Then resume the concept according to which through sub-diameter strokes , External areas increase their curvature while those inside the decrease,

how to parabolize a low focal ratio mirror ( F2-F4 ) – first part

Aug 24, 2015Massimo MarconiParabolizzazionecaustic, parabolic mirror, sub diameter

STARTING BALL AND FINAL PARABOLA the reflection of light emanating from infinity on a spherical surface does not generate, as it is known, a single focus point, but rather a figure that “caustic reflection” which identifies the rotation surface where they concentrate the reflections of a point source . As you can be seen in Figure

Curvature Correction with Sub-diameter

Apr 4, 2015Massimo Marconi13 CommentsCorrection of defectsparabolic mirror, sub diameter

We saw in a previous article the general operation of the racing technique with sub-diameter. On that occasion, we examined the aspect relating to processing by identifying the zones or circular sectors in which the material removal takes place more or less effectively. Let us now go into more detail about the effects that this process produces

Turned down edge: correction with sub-diameter

Dec 14, 2014Massimo Marconi2 CommentsCorrection of defectssub diameter

One of the most common defects during polishing operations or sfericizzazione is the occurrence of the turned down edge. HOW DOES it PRESENTS With “turned down edge” o TDE ( turned down edge) defining a limited circular ring close to the edge of the mirror, which rapidly increases its radius of curvature with respect to the remaining surface

Strokes “W”, sub diameter 50%

Sep 7, 2014Massimo MarconiTechniquesstroke, sub diameter, tools

This type of technique can be used in the first phase of the generation of the parabolic shape of short focal mirrors or large diameter, the mirror is always and only in the lower position. hand position ( for small tools below 15 cm)It is the one with the thumbs pushing a

Sub diameter tools, general aspects.

Aug 26, 2014Massimo Marconi5 CommentsTechniquessub diameter, tools

The techniques with sub-diameter tool, try to solve some of the problems that arise with the use of the full-diameter at the time when the size or the curvatures of the optical surface of the work, assume limit values in which standard techniques can be ineffective or difficult to apply or even, in some cases, counterproductive. we can summarize