Apparatus for measuring void ratios by using radiation

Claim 1

In apparatus for measuring a void ratio by using X-Ray radiation of the type comprising a hollow measuring unit through which fluid containing voids flows, a source of X-ray radiation and a radiation detector disposed on opposite sides of said measuring unit, the improvement which comprises an X-ray opaque rotary disc disposed between said measuring unit and said radiation detector and said disc having a first plurality of openings which are relatively small circular measuring openings substantially equal to the size of the voids to be detected and are equally spaced around a first circular path on said rotary disc for transmitting said radiation to said detector after passing through said hollow measuring unit, said measuring openings forming fine circular radiation beams, means for measuring the rotational angle of the disc comprising a second plurality of openings equally spaced around said disc on a second circular path which is radially spaced from said first circular path; means on one side of the disc for sending an optical signal through the second plurality of opening and an optical detector therefor on the other side of the disc and means connected to said optical detector for measuring the rotational angle of the disc and means for driving the disc at a constant speed.