A single-, two- or three-axis opto-electronic encoder, or error-inputting device, with an optical scale which is overall cylindrical, spherical or volumetric, as opposed to extant planar, circular optical scales; mostly parallel rays of light enter from the cylindrical or spherical surface of the scale, travel, with or without being modulated in intensity due to rotation/rotations of, or distortion/distortions in, the scale, along elliptical and/or circular sectional planes of the scale and exit to fall upon an obstructing opto-electronic sensor or a plurality of such sensors. A photo-transmissive spherical float on a photo-opaque liquid sealed inside a spherical optical scale, moving vertically under the influence of an external force, upwardly displacing the photo-opaque liquid to block the light that enters the spherical optical scale from reaching any of the opto-electronic sensors, produces a distinct electronic condition for auxiliary use in addition to or conjunction with encoder or error-inputting device output or outputs.