1 Scope
This part of GB/T 7962 specifies the test method, test steps and data processing for the optical homogeneity of colourless optical glass.
This part is applicable to the measurement for optical homogeneity of colourless optical glass with a diameter or side length of greater than 100mm and a thickness of not less than 40mm.
2 Normative references
The following documents contain provisions which, through reference in this part of GB/T 7962, constitute provisions of this part. For dated references, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, parties to agreements based on this part are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest editions apply to this part.
GB/T 903 Colourless optical glass
3 Terms and definitions
For the purposes of this part, the following terms and definitions apply.
3.1
optical homogeneity
maximum positive and negative deviations of the refractive index at each point of the glass from the average refractive index of the glass, expressed by Δn+ and Δn- respectively
3.2
Fizeau plano-interferometry
interferometry by which a certain inclination angle is formed between the standard plane and the plane to be inspected, and the orientation and size of the air wedge between them is changed, so that the optical path difference of the two coherent light beams gradually changes along the direction of the main cross section of the air wedge, thereby forming equal-thickness interference fringes
3.3
peak value and valley value
peak value and valley value of transmission wavefront
taking the best ideal transmission wavefront as the "zero plane" (data statistics average plane), the peak value (P) and valley value (V) of glass transmission wavefront are respectively defined as positive value and negative value within the range of test caliber
3.4
peak-valley value
peak-valley value of transmission wavefront within the range of test aperture, expressed by PV, and PV=P-V
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus
6 Sample
7 Test conditions
8 Measuring steps
9 Data processing
