Materials & Engineering
Optical Glass Grade Cross-Reference — CDGM, Schott, Hoya & Ohara Equivalent Grades
Questions buyers ask before sending a drawing:

  • “The drawing says Schott N-BK7 — which CDGM grade matches?”
  • “Can H-ZF6 be substituted directly for N-SF4?”
  • “Will a substitute affect transmission or imaging?”
  • “Are material certificates traceable per batch?”
We manufacture to the drawing’s specified glass, and confirm any substitution with your engineer first. HSD cross-references CDGM, SCHOTT, HOYA, OHARA and HIKARI grades by nd/vd, then checks transmission, chemical durability, thermal behaviour and abrasion. No silent material changes.

Material certificates traceable per batch · NDA before drawings · quote within 24 hours.

Send Your Drawing →Email [email protected]

The Problem

A wrong grade match is a scrap-risk, not a paperwork detail

European drawings use Schott and Ohara grades; Chinese process systems use CDGM grades. When the two do not line up, the problem usually appears after production starts — not at the quote stage.

1 · Judging equivalence by refractive index alone. Similar nd/vd does not mean equivalent: transmission limits, chemical durability and thermal coefficients can differ.
How HSD prevents it: after matching grades by nd/vd, we verify specific gravity, abrasion, environmental compliance and get written confirmation.

2 · Silent material substitution. A substitute without written approval can fail incoming inspection or end the batch in scrap.
How HSD prevents it: we produce to the drawing’s specified glass; any substitution is confirmed with your engineer first.

3 · Certificates that do not line up. A COA exists, but material certificates and lot traceability are missing — incoming inspection and customs get stuck.
How HSD prevents it: material certificates ship per batch, traceable to the material supplier.

4 · Image drift after substitution. A temperature-sensitive system can shift when the substitute has a different dn/dT.
How HSD prevents it: thermal, transmission and durability differences are put on the table during material confirmation.

Capability

Material cross-reference and confirmation, four areas

Grade cross-reference
System Series covered
CDGM H-K / H-ZK / H-LAK / H-ZF and more
SCHOTT N-BK7 / N-SK / N-LAK / N-SF
HOYA / OHARA / HIKARI E- / S- / E- series equivalents
Confirmation flow
Step Action
1 Match grades by nd/vd from the drawing
2 Check transmission, durability, thermal behaviour
3 Substitution requires written confirmation
Quality documents
Document Content
COA Measured values per batch
Material certificate Traceable per batch
Material confirmation Written record before substitution
Delivery
Item Commitment
Quote Within 24 h of drawing
Confidentiality NDA standard
System ISO 9001:2015
Cross-Reference

Common grade matches (excerpt)

nd/vd CDGM SCHOTT HOYA OHARA
1.51680/64.20 H-K9L N-BK7 E-BSC7 S-BSL7
1.62299/58.12 H-ZK21 N-SK15 E-BACD15 S-BSM15
1.71300/53.83 H-LAK7 N-LAK8 E-LAC8 S-LAL8
1.72916/54.70 H-LAK52 N-LAK34 E-TAC8 S-LAL18
1.67270/32.71 H-ZF2 N-SF5 E-FD5 S-TIH25
1.75520/27.53 H-ZF6 N-SF4 E-FFD4 S-TIH4
1.80518/25.46 H-ZF7L N-SF6 FD60 S-TIH6
1.84666/23.83 H-ZF52 N-SF57 FDS90 S-TIH53

Full 143-row table with environmental mark, specific gravity and abrasion (FA):

⬇ Download Full Cross-Reference PDF

Production Evidence

Shop-floor photos

Production photo 1

Production workshop
Production photo 2

Production workshop
Production photo 3

Production workshop
Production photo 4

Production workshop
Photos show HSD’s own production floor. Customer designs are never displayed; final specifications per the drawing confirmed with your engineer.
FAQ

Common material questions

N-BK7 and H-K9L are often listed as equivalents — are they actually identical?
They match on nd/vd (517/642) and are listed as equivalent grades by industry references such as Edmund Optics. For production, equivalence also depends on transmission, chemical durability and thermal expansion. HSD confirms the full set against the drawing before production.
Can you substitute a CDGM grade for the Schott grade on my drawing?
Yes, after cross-referencing and verification. Any substitution is documented and confirmed with your engineer before production — we never change material silently.
Does every Schott or Ohara grade have a CDGM equivalent?
No. Not every grade has a direct equivalent — industry equivalence tables leave several grades without a match (for example, N-PK51 and S-TIH18 have no direct CDGM cross-reference). Each grade is checked individually against the drawing.
Will changing the glass affect thermal behaviour?
It can. Coefficient of thermal expansion and dn/dT differ between grades (for example, 7.10 vs 9.00 x10-6/K between common crowns and flints). Temperature-sensitive systems are reviewed at the material confirmation stage.

Have a drawing that needs material confirmation?

Grade cross-reference + drawing review · NDA protected · quote within 24 hours.

Send Your Drawing →Email [email protected]

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