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Optical Glass Materials
Preform Material for Precision Molding

Preform Material for Precision Molding

Preform material for precision molding lens is optimized for molding aspherical or other special lenses. Low temperature pressing and lens manufacture without polishing are possible with this glass, enabling drastic shortening of the lens manufacturing process and reducing cost.
SUMITA provides the preform material as gobs or polished preforms (polished balls or polished near-net preforms).

Gob Preforms (Unpolished preforms)

"Gob preform" is a preform produced directly from the melt without any additional surface processing. Precision glass molding is a replicative process that allows the production of high precision optical components from this glass (gobs or preforms) without grinding and polishing.

Specifications of Precision Gob Preform

Weight 250 - 350 mg 350 - 500 mg 500 - 700 mg 700 - 1000 mg 1000 - 1200 mg 1200 - 1500 mg More than 1500 mg
Weight tolerance ± 5 mg ± 5 mg ± 5 - 10 mg ± 10 mg ± 10 - 15 mg ± 15 mg ± 20 mg
Shape Biconvex, plano-convex, convex-concave
Min. quantity/lot 30,000 pcs/lot Upon request
  • * For minimum quantity, please contact us for details.
  • * Weight tolerance depends on the glass type.
  • * Customized products within our specification are possible.
Display list of index by glass type (Gobs only)
Glass type Optical constants After molding *1 Tg At αx10-7 DW Specific gravity Supply forms *2 Coloration *3
nd νd nd νd (°C) (°C) S.g
K-PSFn185 1.85070 26.9 1.84524 27.1 537 585 101 1 4.17 ● (40)/36※4
K-PSFn3 1.83917 23.9 1.83352 24.0 477 515 118 1 3.90 ○ (43)/38※4
K-VC181 1.81055 41.1 1.80614 41.0 548 584 79 1 4.71 ○ 40/34
K-VC89 1.81000 41.0 1.80589 40.9 528 559 83 1 4.75 ○ 40/34
K-VC100 1.80400 43.6 1.79916 43.5 570 609 72 1 4.71 ● 40/34
K-VC179 1.79890 41.8 1.79441 41.8 523 561 80 1 4.65 ● 39/34
K-VC174 1.74850 45.3 ※7 ※7 524 562 105 1 3.92 ● 38/31
K-CD120 1.72250 29.2 1.71468 29.6 508 549 119 1 3.01 ○ 43/36
K-ZnSF8 1.71430 38.9 1.71142 38.9 518 546 60 2 3.72 ● 39/34
K-VC80 1.69384 53.1 1.68984 52.8 530 566 94 1 3.81 ○ 36/29
K-CD45 1.69320 33.7 1.68673 34.1 470 507 121 1 3.13 ○ 41/35
K-VC78 1.66955 55.4 1.66625 55.2 520 556 100 1 3.44 ○ 35/28
K-LCV93 1.66520 47.3 1.66355 47.2 547 578 46 1 3.64 ○ 38/33
K-PSFn166 1.66300 34.4 1.65858 34.3 488 538 113 1 3.11 ● 39/34
K-LCV161 1.61820 45.3 1.61477 45.6 426 469 67 2 3.26 ● 36/32
K-PSK200 1.61305 59.0 1.61083 58.9 386 412 123 1 3.38 ○ 34/31
K-VC79 1.61035 57.9 1.60736 57.5 516 553 93 2 3.09 ○ 34/29
K-PSK300 1.59950 65.6 1.59690 65.3 463 498 128 2 3.49 ○ 36/31
K-PSK100 1.59170 60.7 1.58793 60.5 390 415 114 1 3.24 ○ 36/32
K-SKLD100 1.59110 60.7 1.58773 60.4 520 560 85 3 2.69 ○ 36/30
K-SKLD5 1.58913 61.2 1.58606 61.0 521 560 82 3 2.67 ○ 36/30
K-CSK120 1.58700 59.6 1.58444 59.2 498 536 91 2 3.00 ○ 35/31
K-SKLD120 1.58680 59.8 1.58401 59.5 512 548 85 1 2.64 ○ 35/30
K-SKLD200 1.58660 59.0 1.58355 58.8 507 548 88 1 2.70 ○ 35/30
K-CSK158 1.58400 56.9 1.58157 56.7 473 529 112 2 3.06 ● 34/31
K-PMK155 1.55820 68.2 1.55471 68.0 460 492 126 5※8 2.74 ● 35/28
K-PG375 1.54250 62.9 1.53921 62.5 344 367 160※5 2 2.90 ○ 36/31
K-PBK60 1.52740 62.3 1.52483 61.9 495 549 74 1 2.45 ○ 34/29
K-PBK50 1.52250 62.3 1.52023 62.0 481 518 92 2 2.43 ○ 34/29
  • *1 Reference value after SUMITA molding process
  • *2 〇: Gobs and polished preforms. Please contact us on possible dimensions. ●: Polished preforms. Please contact us on availability of gobs.
  • *3 Wavelength for transmittance 0.8 and 0.05 in units of 10 nm
  • *4 Wavelength for transmittance 0.7 and 0.05 in units of 10 nm
  • *5 Temperature range: 50 – 250℃
  • *6 Temperature range: 50 – 200℃
  • *7 Measurement in progress
  • *8 Additional information is available upon request.
  • *9 Some glasses can be out-of-stock. Contact us to check stock availability in advance.

Polished Preforms

For such optical glass types that gob preform is difficult to be manufactured, it is general to apply polished “ball” or “near-net shape preform”.
SUMITA's polished preforms are available for a wide range of applications covering from small to mass production with consistent quality for precision molding lenses.

Specifications for Polished Preform

Shape Ball Near-net shape preform
Diameter (mm) φ1.2 – 20 Upon request
Sphericity (mm) Less than φ±0.005
Surface finish Mirror polishing
  • * For other specifications, please contact us.
  • * Concerning K-PSFn1 and K-PSFn3, please contact us in advance, since solarization may occur under certain conditions of use.
  • * Customized products within our specification are possible.
Display the list of index by glass type
Glass type Optical constants After molding *1 Tg At αx10-7 DW Specific gravity Supply forms *2 Coloration *3
nd νd nd νd (°C) (°C) S.g
K-PSFn214P 2.14400 17.8 2.13919 17.8 427 452 99 1 7.07 △ (52)/42※4
K-PSFn2 2.00170 20.6 1.99670 20.6 480 514 92 1 5.48 △ (50)/40※4
K-PSFn1 1.90680 21.2 1.89948 21.4 498 543 102 1 4.15 △ (49)/39※4
K-PSFn190 1.90460 21.5 1.89816 21.6 497 551 93 1 4.15 △ (43)/39※4
K-VC91 1.88660 35.0 1.88176 34.9 589 638 95 1 4.87 △ (41)/36※4
K-VC185 1.85375 40.6 1.84909 40.4 617 655 70 1 5.00 △ (37)/32※4
K-VC90 1.85280 39.0 1.84859 38.9 583 633 94 1 4.98 △ (38)/34※4
K-PSFn185 1.85070 26.9 1.84524 27.1 537 585 101 1 4.17 ● (40)/36※4
K-VC99 1.85060 41.6 1.84604 41.5 616 653 73 1 5.15 △ (38)/32※4
K-PSFn3 1.83917 23.9 1.83352 24.0 477 515 118 1 3.90 ○ (43)/38※4
K-VC181 1.81055 41.1 1.80614 41.0 548 584 79 1 4.71 ○ 40/34
K-VC89 1.81000 41.0 1.80589 40.9 528 559 83 1 4.75 ○ 40/34
K-VC100 1.80400 43.6 1.79916 43.5 570 609 72 1 4.71 ● 40/34
K-VC179 1.79890 41.8 1.79441 41.8 523 561 80 1 4.65 ● 39/34
K-LaFK50 1.77200 50.0 1.76831 49.6 560 592 90 1 5.20 △ 37/29
K-LaFK50T 1.76600 49.8 1.76209 49.6 576 612 81 1 4.75 △ 37/30
K-VC82 1.75550 45.6 1.75029 45.4 526 563 80 1 4.25 △ 38/33
K-VC174 1.74850 45.3 ※7 ※7 524 562 105 1 3.92 ● 38/31
K-CD120 1.72250 29.2 1.71468 29.6 508 549 119 1 3.01 ○ 43/36
K-ZnSF8 1.71430 38.9 1.71142 38.9 518 546 60 2 3.72 ● 39/34
K-LaFK58 1.69560 59.0 1.69097 58.6 542 577 93 1 4.56 △ 36/28
K-LaFK55 1.69400 56.3 1.68874 55.7 514 556 91 1 4.34 △ 37/29
K-VC80 1.69384 53.1 1.68984 52.8 530 566 94 1 3.81 ○ 36/29
K-CD45 1.69320 33.7 1.68673 34.1 470 507 121 1 3.13 ○ 41/35
K-CD300 1.69220 29.6 1.68558 29.9 482 519 141 1 2.78 △ 41/36
K-VC78 1.66955 55.4 1.66625 55.2 520 556 100 1 3.44 ○ 35/28
K-LCV93 1.66520 47.3 1.66355 47.2 547 578 46 1 3.64 ○ 38/33
K-PSFn166 1.66300 34.4 1.65858 34.3 488 538 113 1 3.11 ● 39/34
K-LaFK65 1.65670 62.3 1.65224 62.0 506 542 103 1 4.36 △ 36/28
K-LaFK63 1.63860 63.4 1.63463 63.0 486 524 118 1 4.36 △ 35/25
K-LaFK60 1.63246 63.8 1.62847 63.2 485 528 114 1 4.27 △ 38/28
K-LCV161 1.61820 45.3 1.61477 45.6 426 469 67 2 3.26 ● 36/32
K-PSK200 1.61305 59.0 1.61083 58.9 386 412 123 1 3.38 ○ 34/31
K-VC79 1.61035 57.9 1.60736 57.5 516 553 93 2 3.09 ○ 34/29
K-SKLD310 1.60420 48.9 ※7 ※7 519 568 71 1 2.72 △ 37/34
K-PSK300 1.59950 65.6 1.59690 65.3 463 498 128 2 3.49 ○ 36/31
K-PSK400 1.59500 67.8 1.59179 67.6 568 597 129 1 4.05 △ 37/32
K-GFK68 1.59240 68.3 1.58999 68.1 512 536 152 1 4.51 △ 34/28
K-PSK100 1.59170 60.7 1.58793 60.5 390 415 114 1 3.24 ○ 36/32
K-SKLD100 1.59110 60.7 1.58773 60.4 520 560 85 3 2.69 ○ 36/30
K-SKLD5 1.58913 61.2 1.58606 61.0 521 560 82 3 2.67 ○ 36/30
K-CSK120 1.58700 59.6 1.58444 59.2 498 536 91 2 3.00 ○ 35/31
K-SKLD120 1.58680 59.8 1.58401 59.5 512 548 85 1 2.64 ○ 35/30
K-SKLD200 1.58660 59.0 1.58355 58.8 507 548 88 1 2.70 ○ 35/30
K-CSK158 1.58400 56.9 1.58157 56.7 473 529 112 2 3.06 ● 34/31
K-GFK70 1.56907 71.3 1.56626 71.2 485 509 156 1 4.48 △ 34/28
K-SKLD300 1.56420 60.4 1.56124 60.1 509 551 72 1 2.60 △ 35/30
K-PMK155 1.55820 68.2 1.55471 68.0 460 492 126 5※8 2.74 ● 35/28
K-PSK500 1.55215 71.9 1.55000 71.7 495 526 129 1 3.76 △ 34/27
K-PG375 1.54250 62.9 1.53921 62.5 344 367 160※5 2 2.90 ○ 36/31
K-PBK60 1.52740 62.3 1.52483 61.9 495 549 74 1 2.45 ○ 34/29
K-PMK30 1.52500 70.4 1.52003 69.9 528 572 87 2 2.60 △ 33/29
K-PBK50 1.52250 62.3 1.52023 62.0 481 518 92 2 2.43 ○ 34/29
K-PBK40 1.51760 63.5 1.51497 63.4 501 549 73 2 2.39 △ 33/29
K-PG325 1.50670 70.5 1.50506 70.3 288 317 165※6 1 3.00 △ 34/30
K-PFK80 1.49700 81.5 1.49533 80.9 461 483 154 1 3.60 △ 34/27
K-PFK85 1.48563 85.2 1.48375 85.0 452 484 163 1 3.97 △ 34/29
K-PFK90 1.45880 90.0 1.45733 89.8 431 461 165 1 3.72 △ 34/29
K-CaFK95 1.43425 95.0 1.43312 95.0 431 450 167 1 3.54 △ 33/28
  • *1 Reference value after SUMITA molding process
  • *2 〇: Gobs and polished preforms. Please contact us on possible dimensions. ●: Polished preforms. Please contact us on availability of gobs. △: Polished preforms.
  • *3 Wavelength for transmittance 0.8 and 0.05 in units of 10 nm
  • *4 Wavelength for transmittance 0.7 and 0.05 in units of 10 nm
  • *5 Temperature range: 50 - 250℃
  • *6 Temperature range: 50 - 200℃
  • *7 Measurement in progress
  • *8 Additional information is available upon request.
  • *9 Some glasses can be out-of-stock. Contact us to check stock availability in advance.
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