VG20 - a new NIR absorbing optical filter glass Dr. Ralf Biertümpfel 14.05.2013
Agenda 2 Agenda Introduction to absorption filter glass NIR absorbing glasses VG20 properties and advantages
Introduction 3 SCHOTT AG Business segments Home Appliances Precision Materials Optical Industries Home Tech Pharmaceutical Systems Advanced Optics Flat Glass Electronic Packaging Lighting and Imaging
Introduction 4 SCHOTT Advanced Optics: materials and legal regulations IMSU Integrated Management System for Safety and Environmental Protection EHS Environmental, Health and Safety Management System RoHS European Regulation on hazardous substances Some of the optical filter glasses contain lead or cadmium. They are in compliance with RoHS according to exemption 13b documented in ANNEX III of the directive 2011/65/EU REACH Registration, Evaluation and Authorization of Chemical Substances
Introduction 5 Absorption Filter Optical Filter Glass Volume Filter Light source Filter Detector Unwanted light spectrum is absorbed and dissipated as heat Optical filter glass is also called: color filter absorption filter volume filter
Introduction 6
Agenda 7 Agenda Introduction to absorption filter glass NIR absorbing glasses VG20 properties and advantages
NIR absorbing glasses 8 Requirements for NIR / IR absorbers Transmitting visible light and preserve colors. Absorbing NIR light. Steep transition between passband region and blocking region. Heat resistance maintain optical properties. Suitable for imaging optics: reproducible optical properties high stability of refractive index low variation of cut-off wavelength batch to batch repeatability
NIR absorbing glasses 9 Transmittance of NIR / IR absorbers VG20 S8022, S8023 BG60, BG61, BG62 BG38 to BG55 KG1, KG2, KG3, KG5
NIR absorbing glasses 10 More details: diabatic scale of transmittance of NIR / IR absorbers with true color vision BG39 BG42 KG5 BG62
Agenda 11 Agenda Introduction to absorption filter glass NIR absorbing glasses VG20 properties and advantages
VG20 properties and advantages 12 VG20 has much higher absorption in the NIR thickness = 1 mm 10-5 thickness = 2 mm 10-8
VG20 properties and advantages 13 Smallest thickness for low transmittance at 633 nm
VG20 properties and advantages 14 True color vision: red light is absobed, other colors transmit through the filter VG20
VG20 properties and advantages 15 VG20 has high optical quality and is optimized for imaging optics n d = 1,5405 n e = 1,5426 n d = 60,6 n e = 60,2
VG20 properties and advantages 16 Environmentally Robust: Advantage of VG20 in hot and humid conditions High heat and humidity tests (85 C / 85 %rh) Clear glass as well as plastic can show surface corrosion. Typically this effect is more dominant for blue glasses. Normal Blue Glass (like BG39) is a phosphate based glass. BG60/BG61: fluoro-phosphate glasses exhibit much less corrosion New VG20 exhibits same environmental properties as BG60 Illustration of corrosion: Blue Glass before test Blue Glass with severe corrosion VG20 after 250h 85 C / 85 %rh
VG20 properties and advantages 17 VG20 is available as polished filters or as coated component Available sizes: up to 80 mm (greater size on request) Minimum thickness = 0.7 mm Surface qualities standard = 60/40 or 5/3x0.63 premium = 40/20 or 5/3x0.16 Wavefront deformation is low Additional coatings: AR UV- and/or NIR-cutoff etc
VG20 a NIR absorbing optical glass filter 18 SCHOTT s VG20 uniqueness Climatic resistance Excellent climatic resistance Uncoated filter glass withstands more than 250 h at 85 C / 85% rh VG20 is easily coated. Reproducability & Repeatability Continuous production less variation than pot melt High stability of transmission vs. wavelength characteristics Reproducible optical properties (refractive index & dispersion) Negligible variations from melt to melt Application True color vision High absorption in the NIR at a small glass thickness Applicable for laser safety, imaging optics, NVIS
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1. History of Filters at SCHOTT 21 129 years of experience 1884 SCHOTT was founded Production of optical glasses 1886 Production of first filter glasses Source: SCHOTT Optischer Glaskatalog, July 1886, p. 19 Source: SCHOTT AG (Glasmuseum, Jena), July 1886
1. History of Filters at SCHOTT 22 History of Interference Filters Dr. Walter Geffcken (SCHOTT) was one of the first who invented interference filters, especially AR coatings. 1939 Patent of Metal dielectric interference filters (Fabry Perot resonator) DE 716153 1940 Patent of Coatings with reduced surface reflections CH223344 1942 Patent of All dielectric interference filters using several optical films DE742463
3. Filter Glass Catalogue 23 The new catalogue for Optical Filter Glass Our new catalogue of Optical Filter Glasses has two parts Description part Introduction Nomenclature Description of glass properties Important formulas Background information
3. Filter Glass Catalogue 24 The new catalogue for Optical Filter Glass Our new catalogue of Optical Filter Glasses has two parts Properties part Portfolio Guaranteed values Detailed data Transmittance curves Geometry of polished filters
5. Interference Filter Catalogue 25 The new Catalogue of Interference Filter Our new catalogue of Interference Filters has two parts Description part Introduction Basics of interference Description filter properties Important formulas and definitions Background information
5. Interference Filter Catalogue 26 The new Catalogue of Interference Filter Our new catalogue of Interference Filters has two parts Properties part Portfolio Guaranteed values Detailed data Typical transmittance curves Special filters