Precision optical flats are Fused Silica optical components that are used as a reference against which the flatness of an unknown surface can be determined. For less demanding jobs Tower offers them made from BK7 with a flatness specified as λ/4 or better. These optical flats may also be used as windows.

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Single Sided and Double Sided Optical Flats
  • Fused Silica
  • Flatness of λ/10 or λ/20
  • Single and double sided
  • Easy to use
  • From 25mm to 200mm
  • Precision Ground and Polished
  • Low cost BK7 with reduced quality
For Single and Dual Surface Optical Flats
Material:BK7Fused Silica
Ref Index:nd-1.517nd=1.458
Abbe Number:vd=64.07vd=67.7
Density:2.53 g/cm32.2 g/cm3
Exp. Coefficient:7.1 × 10-6/°C0.55 × 10-6/°C
Surface Quality:60/40
Parallelism:<1 arc min
Back Surface (Single):1-2 λ @633nm
Dia. Tolerance:±1mm
Thickness Tolerance:±1.5mm

Diameter (mm)Thickness (mm)MaterialSingle or Dual SurfaceLambda/10Lambda/20
Catlog No.PriceCatlog No.Price
2512.5Fused SillicaSingle4542-0002$140.004542-0022Call for price
2512.5Fused SillicaDual4542-0004$240.00
5015Fused SillicaSingle4542-0006$400.004542-0024Call for price
5015Fused SillicaDual4542-0008$520.00
10020Fused SillicaSingle4542-0010$680.004542-0026Call for price
10020Fused SillicaDual4542-0012$860.00
15025Fused SillicaSingle4542-0014$1,447.00
15025Fused SillicaDual4542-0016$1,630.00
20038Fused SillicaSingle4542-0018$2,872.00
20038Fused SillicaDual4542-0020$3,052.00
Lambda/4 or better
2512.5BK7Single4542-0001$75.00
2512.5BK7Dual4542-0003$83.00
5015BK7Single4542-0005$75.00
5015BK7Dual4542-0007$100.00
10020BK7Single4542-0009$215.00
10020BK7Dual4542-0011$300.00
15025BK7Single4542-0013$450.00
15025BK7Dual4542-0015$580.00
20038BK7Single4542-0017$1,350
20038BK7Dual4542-0019$1,600

If a carrying case is required order 1405-0008 for up to 100mm for $50.00, and 1405-0009 for 150 & 200mm for $75.00 

We make custom versions of everything on this site. Send us your drawings or specifications and we will provide a quotation.