Precision Optical Flats

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: BK7 Fused Silica
Ref Index: nd-1.517 nd=1.458
Abbe Number: vd=64.07 vd=67.7
Density: 2.53 g/cm3 2.2 g/cm3
Exp. Coefficient: 7.1 × 10-6/°C 0.55 × 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) Material Single or Dual Surface Lambda/10 Lambda/20
Catlog No. Price Catlog No. Price
25 12.5 Fused Sillica Single 4542-0002 $140.00 4542-0022 Call for price
25 12.5 Fused Sillica Dual 4542-0004 $240.00    
50 15 Fused Sillica Single 4542-0006 $400.00 4542-0024 Call for price
50 15 Fused Sillica Dual 4542-0008 $520.00    
100 20 Fused Sillica Single 4542-0010 $680.00 4542-0026 Call for price
100 20 Fused Sillica Dual 4542-0012 $860.00    
150 25 Fused Sillica Single 4542-0014 $1,447.00    
150 25 Fused Sillica Dual 4542-0016 $1,630.00    
200 38 Fused Sillica Single 4542-0018 $2,872.00    
200 38 Fused Sillica Dual 4542-0020 $3,052.00    
        Lambda/4 or better    
25 12.5 BK7 Single 4542-0001 $75.00    
25 12.5 BK7 Dual 4542-0003 $83.00    
50 15 BK7 Single 4542-0005 $75.00    
50 15 BK7 Dual 4542-0007 $100.00    
100 20 BK7 Single 4542-0009 $215.00    
100 20 BK7 Dual 4542-0011 $300.00    
150 25 BK7 Single 4542-0013 $450.00    
150 25 BK7 Dual 4542-0015 $580.00    
200 38 BK7 Single 4542-0017 $800.00    
200 38 BK7 Dual 4542-0019 $1,200.00    

If a carrying case is required order CASE-S for up to 100mm for $20, and CASE-L for 150 & 200mm for $50

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