7. Guarantees of Quality
7.1 Refractive Index and Abbe Number
The measured refractive index and Abbe number values of our fine annealed products will vary from catalogue standards by:
| Refractive index: |  |
± 0.0005 | |||
| Abbe number: |  |
± 0.8% |
Upon request, we will supply blanks of optical glass to the following tolerances:
| Refractive index: | |
± 0.0002 | |||
| Abbe number: | |
± 0.3% |
Please consult us when there exists a special demand for tolerances other than the above.
We urge our customers to enjoy the cost savings and benefits of our close index control, melt to melt, over
long periods of production. Usually, this is done at no extra cost. As a standard, we send certification (melt data)
of refractive indices measured at the spectral lines: C, d, F, g and .
On special request, we can supply measurement values of refractive index taken at other spectral lines.
The following is the accuracy of standard measurements of refractive index and dispersion for raw glass and normal pressed blanks:
| Refractive index: | ± 0.00003 | ||
| Dispersion: | ± 0.00002 |
On request, we shall provide precision measurements of refractive index and dispersion with the following accuracies:
| Refractive index: | ± 0.00001 | ||
| Dispersion: | ± 0.000003 |
Please note, the above accuracies are achieved with the use of our Moeller Wedel Type I Spectrometer. Please contact us for further details concerning our super precision measurement capabilities.
| Fig. 2: Spectrometer |
We will report the environmental temperature, humidity and atmospheric pressure of the room where the precision measurement was undertaken. Please contact us for "ultra-precision measurements" and measurements of spectral lines not included in this catalogue.