India's Largest Producer of Progressive, Bifocal  & Single Vision lenses. Exporting to over 30 countires worldwide.
TECHNICAL DATA OF GLASS
D-BIFOCAL 6.25, 4.25, 8.25 & 2.25 BASE

1.  Source of material

i.                    PGX and PBX
 
          A)    Crown Major                                  +6-6x8mm,+4-6x9mm,+8-6x11mm & +2-6x11.5mm
          B)    Upper Segment                               35 x 14 x6mm
          C)    Barium                                            35 x 23.5 x6mm
 
All above from Corning France.
 ii.                  WHITE
       
          A)    Crown Major                                  +6-6x8 mm, +4-6x9mm,+8-6x11mm & +2-6x11.5mm
          B)    Upper Segment                               35 x 14 x6mm
          C)    Barium                                            35 x 23.5 x6mm
 
White blank all sourced from Schott Germany.
 
2)  Final Specifications of semi-finished bifocals:
 
 
Base Redius
Thickness
6.25 base
84.764
6.0mm CT
4.25 base
125.721
7.0mm CT
8.25 base
64.567
9.0mm CT
2.25 base
233.482
8.0mm CT
 3)     De centration:   Distance and reading centers in mm
 
       X= Horizontal Difference        = 5.0
             Between 2 centres
       Y= Detum line below center    = 4.0
       Z= Segment center below        = 5.0
             Datum line
 
4)  Segment Depth in mm :

 

 

 

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

 

 

 

 

 

 

 

 

 

 

 

BASE 6.25

1.56

1.94

1.18

1.38

1.56

1.74

1.41

1.56

1.70

 

 

 

 

 

 

 

 

 

 

 

BASE 4.25

0.80

0.96

1.17

1.36

0.99

1.27

1.41

1.55

1.68

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