Ohara Corporation
Home   Home
Contact Us   Contact Us

i-Line High Homogeneity Glass

These 13 glass types have excellent internal transmittance in the near UV (>98% at i-line, 365 nm) and are solarization resistant. They can be produced in large sizes with outstanding homogeneity values
(+/- 0.5 x 10-6). These glasses are ideally suited for use in semiconductor optics (stepper cameras and illumination systems) and astronomical optics (spectragraph cameras, etc.).

i-Line PDF Information Sheet

Glass Type Internal
Transmittance
10mm thick
(365nm)
Solarization
Resistance
Optical Homogeneity
Capability
Glass Type (x10-6)
Deviation of
ni within a
single lot
(x10-5)
Tolerance of
Refractive Index
(x10-5)
Dia 160 Dia 210 Dia 260
S-FPL51Y 0.997 Good 1.0 - - 2 +2020
S-FSL5Y 0.999 Good 0.5 0.8 1.0 2 +1520
BSL7Y 0.998 Good 0.5 0.8 1.0 1 +2020
BAL15Y 0.994 Good 0.5 0.8 1.0 2 +1020
BAL35Y 0.996 Good 0.5 0.8 1.0 2 +2020
BSM51Y 0.995 Good 0.5 0.8 1.0 2 +3020
PBL1Y 0.997 Good 0.5 0.8 1.0 2 +1020
PBL6Y 0.998 Good 0.5 0.8 1.0 2 +1020
PBL25Y 0.995 Good 0.5 0.8 1.0 2 +1020
PBL26Y 0.996 Good 0.5 0.8 1.0 2 +1020
PBL35Y 0.997 Good ±0.5 ±0.8 ±1.0 ±2x10-5 +10±20
PBM2Y 0.986 Good 0.5 0.8 1.0 2 +1020
PBM8Y 0.991 Good 0.5 0.8 1.0 2 +1020
PBM18Y 0.993 Good 0.5 0.8 1.0 2 +1020

Explanation For Table of i-Line Glass

1- Internal Transmittance
Internal transmittance of the glass is indicated as guaranteed minimum transmittance at 365nm (10 and 25 mm sample thickness). Please note this is internal transmittance, reflection losses are not included.

2- Solarization
The degree of solarization is indicated as a decrease in transmittance caused by radiation from a super high pressure mercury-vapor lamp. The detailed measurement method is described in the "Japanese Optical Glass Industrial Standard (JOGIS)".

3-Optical Homogeneity

Optical Homogeneity (nΔ) is guaranteed by use of our He-Ne laser interferometers. The nΔ specification is indicated for three diameter ranges ( 160 mm or less, 210 mm or less, 260 mm or less) due to the nΔ variances caused by glass type, size, and shape. Please note, if the ordered thickness is less than 25 mm, we will use a 25 mm thick test piece for n measurement. Please contact us when lower nΔ specifications are required.

4- Refractive Index (ni) Variation within one Lot (Sn Standard)
The indicated Sn value is the refractive index variation after annealing within a single batch (same melt, same annealing run).

5- Refractive Index Tolerance
The standard refractive index (ni) of our i-line glass is
higher than our catalogue nominal values. This is due to
the longer annealing times which are necessary to obtain
the desired homogeneity levels. Longer annealing times
result in higher refractive indices.

Example: +203010-5

+20 (+0.00020) means the increase against our catalogue nominal ni value. The 30 (0.00030) is then the tolerance on the new nominal value. i.e. a glass type having a tolerance of +2030 can vary from -10 (-0.00010) to +50 (+0.00050) against standard catalogue nominal. Please consult us when tighter tolerances are required.

6- Other
By using constants of dispersion formula on the catalog table, refractive indices for any wavelength between 326 to 1129nm can be calculated. When calculating refractive indices for any wavelength between 1129 and 2325nm, please refer to following table.
The constants of dispersion (1129-2325nm)