In optical parts polishing process, its surface shape deviation is generally through the optical model (
Based on the waves are isopach interference principle)
To test, according to
Aperture of recognition and measurement of on any account when sample contact with parts, if both in the contact centre, to highlight circle;
On the other hand, the edge contact between the two, for the low light.
Commonly used identification methods are: 1, the sample around low pressure aperture: when the air gap is narrowing, stripe moving from the edge to the center, aperture and coarsens.
Specular circle: when the air gap is narrowing, stripe from center to edge, aperture also decrease accordingly.
As shown in figure 4 -
2 and low side pressure aperture: when the air gap is narrowing, stripe bending direction of back strength, stripe direction as shown in figure 4
Specular circle: when the air gap is narrowing, stripe bending direction towards strength point, stripe direction as shown in figure 4
3, color sequence judgment method in it, each successive cut short the wavelength of the light from red to violet light, therefore, in the same order of interference, the wavelength, the greater the interfere of the gap is, the greater the when the sequence from the center to the edge of the color is blue, red, yellow for low light;
When the sequence from the center to the edge of the color is yellow, red, blue, specular circle, see figure 4
4, the number of aperture measure the number of aperture, reflects the radius of curvature of test optical surface relative to the reference the size of the optical surface curvature radius deviation.
The greater the aperture, the more deviation.
When the aperture number (
When N> 1)
To effectively test within the scope of half maximum number of stripes to measure diameter direction.
Under white light illumination, usually for the measurement standard color with red, appear on the surface of a few red aperture is a few laps.
Under the condition of less when the aperture of (