Nondestructive method for measuring states of surface and apparatus for carrying out said method

Claim 1

A nondeStructive method for measuring the state of surfaces consisting of the steps of projecting at an oblique angle onto a substantially flat portion of surface constituting an approximately perfect mirror a beam of parallel rays of stabilized intensity, placing an object-grid at right angles to the axis of said beam, placing a centered optical system across the reflected beam of parallel rays and at right angles to the axis thereof, placing a Lummer dividing cube at the downstream focal point or image focal point of said centered system, said Lummer cube emitting two beams having the same light intensity, directing one beam in the line of extension of the incident beam, deflecting the other beam through 90* with respect to the first beam, placing across said direct beam and at right angles to the principal axis thereof an image-grid identical with the objectgrid and capable of small displacements in its plane, locating two grids in the anti-principal planes of said centered optical system, said image-grid being locked in position so as to permit the light beams emitted by the object-grid to pass exactly through said image-grid, focusing said direct beam and said deflected beam each onto a photoelectric cell, adjusting said two photoelectric cells to supply equal currents under the action of the light beam on the Lummer cube, displacing the image-grid in its plane to stop all light beams emitted by the object-grid, and then replacing the portion of surface functioning as a perfect mirror by the portion of surface whose state is to be studied, the quotient of the currents from said two photoelectric cells being characteristic of a given state of surface and the current from said photoelectric cell corresponding to the beam which is deflected by said cube providing the albedo of a given surface state and color.

Claim 3

An apparatus for measuring the state of surfaces comprising a stabilized stationary light source, a collimator for delivering a beam of parallel rays from said source, a support for disposing a substantially flat portion of surface at an oblique angle with respect to said beam, a so-called object-grid which is parallel to the lens of said collimator on the downstream side thereof and mounted across said parallel beam, a centered optical system, a Lummer cube mounted at the downstream focal point or image focal point of said centered system, a so-called image-grid which is positionally adjustable in its plane, the two grids being located in the anti-principal planes of said centered optical system, two photoelectric cells so arranged as to receive respectively the direct beam and the deflected beam emitted by said Lummer cube and two variable diaphragms placed across said direct and deflected beams.

Claim 4

An apparatus for measuring the state of surfaces comprising a stabilized stationary light source, a collimator for delivering a beam of parallel rays from said source, a support for disposing a substantially flat portion of surface at an oblique angle with respect to said beam, a so-called object-grid which is parallel to the lens of said collimator on the downstream side thereof and mounted across said parallel beam, a centered optical system, a Lummer cube mounted at the downstream focal point or image focal point of said centered system, a so-called image-grid which is positionally adjustable in its plane, the two grids being located in the anti-principal planes of said centered optical system, two photoelectric cells so arranged as to receive respectively the direct beam and the deflected beam emitted by said Lummer cube and two variable diaphragms placed across said direct and deflected beams.