Sagital plane

[sevalav]

Hello,

I have a problem to understand where is relay sagital plane on the lens. Look this PDF file. I create this picture to show how I see sagital plane. Is this correct?

[sevalav]

Picture

[chip anderson]

http://www.mellesgriot.com/products/optics/fo_3_2_2.htm

[Darryl Meister]

The best approach is to first imagine the tangential planes of the lens, which also correspond to the cylinder axis meridians. These meridians of the lens are similar to the spokes of a wheel.

At any point along a tangential plane, as you look away from the center of the lens in any particular direction, the sagittal plane is simply the plane perpendicular to the tangential plane, just as the hub of a wheel is perpendicular to each spoke where they connect.

You might find the illustrations of the tangential and sagittal planes at this website useful: Tangential and Sagittal Errors.

[sevalav]

Lets say that we want looking only sagittal plane. On the surface on the lens there is lot of
sagittals planes, like tangentials planes. Infinitely. But we want to see only one, and in 3D.
If we cut the lens and isolate the area where the light strikes and pass throw the lens in only one sagittal plane, we will get a ring (who circumscribe the optical center) with infinitesimal thickness and with „depth“ identically thickness of the lens in that area.
Is that right?
Please, see the picture in PDF file.

[chip anderson]

I'm not the world's expert on this but I'm pretty sure you only get a circle in two circumstances.
1) You have a spherical lens and you only exteend the plane to slightly more or slighly less (either) than the focal length.
2) You have a cylindric lens and have the focal length at "the interval of Sterm" or in other words the point exactly mid-way between it's two focal lenghts (planes.)

Chip

[sevalav]

If we cut the lens and isolate the area where the light strikes and pass throw the lens in only one sagittal plane, we will get a ring (who circumscribe the optical center) with infinitesimal thickness and with „depth“ identically thickness of the lens in that area.
Is that right?
Please, see the picture in PDF file.

I forgot to write: this is a spherical lens .

[sevalav]

Maybe is point of confusion because I don't clear told that for me is not important how this sagittal plan refract a light, where is a focus. As you can see, this is not showed on last picture. I just wont to now is this sagittal plane correct shown on this spherical lens.
For me, now, is more important to know is my last picture accurate, or it is not. Is it good or not.
(The sagittal plane on this picture is created by the light, but the light is not showed. )

[sevalav]

Does anybody know answer for my previous post?