field stop


Also found in: Acronyms.

field stop

[′fēld ‚stäp]
(optics)
An opening, usually circular, in an opaque screen, whose edges determine the limits of the field of view of an optical instrument.
References in periodicals archive ?
Caption: Instead of making an occulting bar to help him see the moons of Mars, long-time observer Stephen James O'Meara fashioned a semi-circular filter using a Wratten #47 gelatin filter affixed in front of the field stop on a medium-power eyepiece using a 11/a-inch outer-diameter O-ring.
*2 Field stop layer: When thin wafer is used for characteristics improvement, withstand voltage is insufficient.
With ON Semiconductor's proprietary Trench Field Stop Technology, we can now give engineers a greater breadth of options to choose from when implementing their power system designs.'
The new IGBT technology and packaging innovation of Fairchild's 650V Field Stop Trench IGBT allows us to achieve all this."
Tenders are invited for Supply of Field Stop IGBT Power Module.
In those cases I used a 7-mm orthoscopic eyepiece with opaque photography tape covering half of its tiny field stop, along with a 2x Barlow.
Observe when Sirius is highest in the south, use your highest magnification, hide Sirius's dazzle behind an occulting bar or the sharp edge of your eyepiece's field stop, and wait patiently for moments of good seeing--but you know that already.
Baader, however, has used a larger field stop than found in traditional orthoscopics, and this has increased the AFOV to 50[degrees].
If you look into the bottom of a simple eyepiece, such as a Plossl, you'll see a sharp-edged ring, or field stop, located below the eyepiece's field lens.
Realizing that such perceptions are highly personal, I initially attributed it to the wide, yet defined, apparent field (I could see the entire circular field stop without moving my eye--something I find comforting).
The system has six elements, 11 optical surfaces, and a field stop. It sounds complicated, and in some ways it is.
To view Abell 12, I affix a thin strip of aluminum foil to the field stop of my eyepiece with rubber cement.