S-LAL12Q

Optical glass type S-LAL12Q: improved chemical durability and lower specific gravity than S-LAL12.

Type Code nc nd nF ng vd s.g. Coloring
S-LAL12Q 678553 1.67417 1.67790 1.68642 1.69307 55.35 3.59 380/-

S-LAL12Q - improved processability and chemical durability

S-LAL12Q is an optical glass with improved workability and durability, which can be an issue for glasses in the S-LAL family. With the same optical performance (refractive index and Abbe number) as S-LAL12, the new S-LAL12Q offers improved properties for lens fabrication processes. S-LAL12Q is ideal for use various applications, such as in-vehicle camera lenses, projectors, and interchangeable lenses for photography.

Advantages

  • Improved chemical durability (compared to S-LAL12)
    Powder method Water Resistance [RW(p)]: Grade 1; Powder method Acid Resistance[RA(p)]: Grade 3
  • Lower specific gravity than S-LAL12 – 3.59
COMPARISON S-LAL12Q (New product) S-LAL12 (Conventional product)
Environmental measures category ○ ○
Refractive index nd 1.67790 1.67790
Abbe number vd 55.35 55.34
Linear expansion coefficient α (10 -7 /℃) -30 ~ +70°C 49 72
+100 ~ +300°C 59 86
Transition point Tg (℃) 689 652
Yield point At (℃) 717 679
Coloring degree λ 80 380 360
λ 5 310 285
Chemical durability RW (P) 1 2
RA(P) 3 Five
W(S) 2 2
SR 51.0 53.0
PR 3.0 4.2
Specific Gravity 3.59 4.01
Knoop hardness Hk 700 (7) 560 (6)
Abrasion degree Aa 62 166
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Optical Glass Melt Frequency & Pricing Guide

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OPTICAL PROPERTIES

2.8 Coloring

Coloring refers to the degree of coloration of the optical glass and is determined by measuring the spectral transmittance, including reflection losses, for a glass sample with a thickness of 10 mm, according to JOGIS-02. From the spectral transmittance curve (Fig. 3), the wavelengths showing the transmittance of 80% and 5%, respectively, are rounded and displayed in 5 nm units. We use this rounding method: the range 0 nm to 2 nm counts as 0 nm, the range 3 nm to 7 nm counts as 5 nm, the range 8 nm to 10 nm counts as 10 nm . For example, if the wavelength with 80% transmittance is 403 nm and the wavelength with 5% transmittance is 357 nm, the coloring is shown as 405/355.
Optical Glass Coloring
For glass types with a high refractive index, nd ≥ 1.84, the reflection loss is large, so the wavelength showing transmittance of 70 % is used, instead of 80 %, and the value is shown in paranethesis. For example, (415).
OPTICAL PROPERTIES

2.1 Refractive Index

Partial dispersion ratio 〔θx, y〕 and anomalous dispersion 〔Δθx, y〕
Anomalous dispersion refers to how far away a glass is from the trend line between the partial dispersion ratio θx, y = (nx-ny) / (nF-nC) for wavelengths x and y and the Abbe number νd. In optical design, glass with anomalous dispersion is required to enable color correction of the secondary spectrum.

Therefore, we have released the θg, F-νd diagram and the θC, t-νd diagram as means to show the relationship between θx, y and νd of each glass type. In order to numerically express the anomalous dispersibility, 511605 (NSL 7) and 620363 (PBM 2) are used as reference glasses, and the straight line connecting these two glass types is considered the “normal” line. The difference between the “normal” line and the vertical coordinates θx, y of each glass type is calculated as anomalous dispersion Δθx, y (Fig. 2). In this catalog, the partial dispersion ratio is θg, F and θC, t, and the anomalous dispersion is Δθg, F and ΔθC, t.

Although NSL 7 and PBM 2 are not currently produced by Ohara, the conventional NSL 7 and PBM 2 values ​​(Table 2) are used as the reference values .

Reference Values:
θc,t
θC,A'
θg,d
θg,F
θi,g
vd
NSL 7
0.8305
0.3492
1.2391
0.5436
1.2185
60.49
PBM 2
0.7168
0.3198
1.2894
0.5828
1.4214
36.26

>θg,F-νd図とΔθg,F

Partial Dispersion Ratio
OPTICAL PROPERTIES

2.6 Relational Constant for Temperature Coefficient of the Refractive Index

Relational constant for temperature coefficient of the refractive index

The temperature coefficient of the absolute refractive index of glass for wavelengths not listed in the data sheet can be calculated as a function of wavelength and temperature. Ohara uses the following equation.

Equation for Temperature Coefficient of absolute refractive index of glass
ｎ(λ,T0)： Refractive index at reference temperature
Ｔ0： Reference temperature (°C) (Ohara defines this as 25°C)
Ｔ： Target temperature (°C)
λ： Vacuum wavelength (μm)
D0、D1、 D2、E0、 E1、λTK： Constant (listed in the data sheet)

To determine the temperature coefficient of the relative refractive index, refer to the equation given in the previous section, “Temperature coefficient of the refractive index”.

Optical Properties
OPTICAL PROPERTIES

2.1 Refractive Index

When light enters the glass, it slows down inversely proportional to the refractive index compared to in a vacuum or in air. The refractive index of optical glass is usually expressed as the speed ratio of light in the air to themedium (glass sample).

The refractive index is measured by sending a predetermined wavelength of light into the sample and measuring theminimum deviation angle of the emitted light bent by refraction, according to JIS B 7071-1. For the 20 spectral lines shown in the table below, numerical values are shown to five decimal places. The refractive indices (principal refractive indices) for d-line (587.56 nm) and e-line (546.07 nm) are also shown to six decimal places.

Spectral Line Symbol t
Light Source Hg Hg Hg Hg Hg
Wavelength (nm) 2325.42 1970.09 1529.58 1128.64 1013.98
Spectral Line Symbol s A′ r C C′
Light Source Cs K He H Cd
Wavelength (nm) 852.11 768.19 706.52 656.27 643.85
Spectral Line Symbol He-Ne D d e F
Light Source レーザー Na He Hg H
Wavelength (nm) 852.11 589.29 587.56 546.07 486.13
Spectral Line Symbol F′ He-Cd g h i
Light Source Cd レーザー Hg Hg Hg
Wavelength (nm) 479.99 441.57 435.835 404.656 365.015
Optical Properties