A combined interference and diffraction pattern, in the form of equidistant interference fringes, resulting from illuminating a vertical metallic wire by a laser beam is analyzed to measure the diameter of four standard wires. The diameters range from 170 to 450 μm . It is found that the error in the diameter measurements increases for small metallic wires and for small distances between the wire and the screen due to scattering effects. The intensity of the incident laser beam was controlled by a pair of sheet polaroids to minimize the scattered radiation. The used technique is highly sensitive, but requires controlled environmental conditions and absence of vibration effects. The expanded uncertainty for k=2 is calculated and found to decrease from U(D)=±1.45 μm for the wire of nominal diameter 170 μm to ±0.57 μm for the diameter 450 μm .

Measurement of wire diameter by optical diffraction

A newly designed comparator was developed for the measurement of both diameter and form of cylinders, spheres and cubes in only a single specimen setting using a contact probe technique. The measurement volume is mm, and the uncertainty aimed at is 0.01 per 100 mm length for calibrations of outer diameters, form and parallelism. The measured values obtained from outer length comparison measurements between three of PTB's standard length comparators and the new comparator agree within nm.

https://iopscience.iop.org/article/10.1088/0957-0233/8/8/003/pdf

A new comparator for measurement of diameter and form of cylinders, spheres and cubes under clean-room conditions

Discrete L-spline filtering in roundness measurements

Displacement Measuring Interferometry

This paper presents an uncertainty analysis for roundness measurements on a glass hemisphere The measurements were carried out with the spindle measuring instrument Talyrond 73 For the correction of spindle errors, a multi-step error separation technique with ten steps was used Various input quantities were investigated such as the form deviations of the hemisphere, the characteristic of the probing system and thermal drift effects Finally, a detailed uncertainty budget was developed It is shown that the standard uncertainty for a single profile point is 15 nm This results in a standard uncertainty of u(RONt) = 3 nm for the roundness deviations of the hemisphere

https://iopscience.iop.org/article/10.1088/0957-0233/12/1/309/pdf

F. Lüdicke

Papers

A new comparator for measurement of diameter and form of cylinders, spheres and cubes under clean-room conditions

An intercomparison on roundness and form measurement