Optical Coatings

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Fundamental Optics ENHANCED ALUMINUM (/023) ULTRAVIOLET-ENHANCED ALUMINUM (/028) Material Properties Optical Specifications Gaussian Beam Optics $ Enhanced performance in the mid-visible region $ Durability of protected aluminum $ R avg > 93% from 450 to 750 nm $ Damage threshold: 0.4 J/cm 2 810%, 10-nsec pulse (33 MW/cm 2 ) at 532 nm, 0.3 J/cm 2 810%, 20-nsec pulse (12 MW/cm 2 ) at 1064 nm By coating the aluminum with a multilayer dielectric film, reflectance is increased over a wide range of wavelengths. The durable enhancing multilayer produces a peak reflectance of 95% with an average across the visible spectrum of 93%. This coating is well suited for applications requiring the durability and reliability of protected aluminum, but with higher reflectance in the mid-visible regions. The reflectance of enhanced aluminum peaks between 530 nm and 580 nm and is high from 400 nm to 800 nm. PERCENT REFLECTANCE 100 95 90 85 80 normal incidence 45° incidence s-plane p-plane typical reflectance curves 400 450 500 550 600 650 700 750 WAVELENGTH IN NANOMETERS $ Maintains reflectance in the ultraviolet region $ Dielectric overcoat prevents oxidation and increases abrasion resistance $ R avg > 86% from 250 to 400 nm $ R avg > 85% from 400 to 700 nm $ Damage threshold: 0.07 J/cm 2 810%, 10-nsec pulse (5.7 MW/cm 2 ) at 355 nm By applying a film of an ultraviolet-transmitting dielectric (usually MgF 2 ), the reflectance of pure, bare aluminum can be preserved in the ultraviolet. The dielectric layer prevents oxidation of the aluminum surface and provides abrasion resistance. While the resulting surface is not as abrasion resistant as our protected aluminum, this coating may be cleaned with care. Reflectance averages over 86% from 250 to 400 nm and over 86% throughout the visible spectrum. This coating can be applied to all Melles Griot mirrors. PERCENT REFLECTANCE 100 90 80 70 60 normal incidence 200 250 300 350 400 WAVELENGTH IN NANOMETERS typical reflectance curve Figure 5.34 Enhanced aluminum coating /023 Figure 5.35 Ultraviolet-enhanced aluminum coating /028 Optical Coatings 5.26 1 Visit Us OnLine! www.mellesgriot.com
INTERNAL SILVER (/036) $ For internal reflection (second-surface) mirrors and prisms only $ Preferred for visible to near-infrared region $ Less polarization effects than aluminum $ R avg > 98% from 400 nm to 1200 nm $ Damage threshold: see /038 (similar specifications) Through most of the visible and near-infrared spectra, silver has higher reflectance than aluminum, at least for a short time following deposition. Rapid oxidation quickly causes unprotected silver coatings to deteriorate. In the internal silver coating, oxidation and tarnish are prevented by coating the external surface with an additional layer of either Inconel ® or copper. The Inconel or copper layers are subsequently painted to increase abrasion resistance. In this way, the high initial reflectance of silver is indefinitely preserved. Silver is frequently used in the near-infrared (the interval containing neodymium and gallium arsenide laser lines) because it avoids the small dip in reflectance exhibited by aluminum in this interval. In the near ultraviolet, silver has very low reflectance, and aluminum is a preferable choice. From the visible into the middleinfrared, silver offers the highest internal reflectance available from a metallic coating. Silver has less effect than aluminum on the polarization state in these regions of the spectrum. PERCENT REFLECTANCE 100 95 90 85 80 normal incidence 400 450 500 550 600 650 700 WAVELENGTH IN NANOMETERS Figure 5.36 Internal silver coating /036 Inconel ® is a registered trademark of EM Industries, Inc. typical reflectance curve PROTECTED SILVER (/038) $ Extremely versatile mirror coating $ Excellent performance for the visible to infrared region $ R avg > 95% from 400 nm to 20 mm $ Can be used for ultrafast Ti:Sapphire laser applications $ Damage threshold: 0.9 J/cm 2 810%, 10-nsec pulse (75 MW/cm 2 ) at 532 nm, 1.6 J/cm 2 810%, 20-nsec pulse (73 MW/cm 2 ) at 1064 nm Melles Griot uses a proprietary coating and edge-sealing technology to offer a first-surface external protected silver coating. In recent tests, the protected silver coating has shown no broadening effect on a 52-femtosecond pulse. This information is presented as a guideline for femtosecond applications and no warranty is implied. Protected silver offers extremely broad performance, from 400 nm to well into the infrared, with excellent durability. Due to the specialized tooling required to produce the protected silver coating, it is offered only on a limited range of substrates. PERCENT REFLECTANCE 100 80 60 40 20 0 400 normal incidence typical reflectance curve 500 600 700 800 900 WAVELENGTH IN NANOMETERS Figure 5.37 Protected silver coating /038 Fundamental Optics Gaussian Beam Optics Optical Specifications Material Properties Optical Coatings Visit Us Online! www.mellesgriot.com 1 5.27
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Fundamental Optics 1 Introduction 1
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Paraxial Formulas SIGN CONVENTIONS
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object F 2 Figure 1.4 image Example
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Figure 1.6 Figure 1.7 f f 2 object
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Figure 1.8 Figure 1.9 INDIVIDUAL EL
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Performance Factors After paraxial
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third-order, monochromatic, spheric
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Positive lens elements usually have
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Lens Shape Aberrations described in
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ay f-numbers 2.7 3.3 4.4 6.7 13.3 S
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AIRY DISC DIAMETER = 2.44 l f/# Fig
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Lens Selection Having discussed the
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Example 4: Diffraction-Limited Perf
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Aberration Balancing To improve sys
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Definition of Terms FOCAL LENGTH (f
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infinity (which is a comfortable vi
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For symmetric lenses (r 2 = 4r 1 ),
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Separation of Nodal Point from Corr
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Gaussian Beam Optics 2 Introduction
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Even if a Gaussian TEM 00 laser-bea
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eam expander INCORPORATING M 2 INTO
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M 2 AND THE LENS EQUATION For real-
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employed when laser power must be c
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Figure 2.13 Keplerian beam expander
Page 49 and 50: Optical Specifications 3 Wavefront
Page 51 and 52: Centration The mechanical axis and
Page 53 and 54: PERFECT RECTANGULAR LENS The MDMTF
Page 55 and 56: The permissible number of maximum-s
Page 57 and 58: Material Properties 4 Material Prop
Page 59 and 60: Introduction Glass manufacturers pr
Page 61 and 62: maximum value for homogeneity withi
Page 63 and 64: Melles Griot Lens Materials Melles
Page 65 and 66: Refractive Index of Five Schott Gla
Page 67 and 68: Synthetic Fused Silica Fused silica
Page 69 and 70: PERCENT INTERNAL TRANSMITTANCE 99.9
Page 71 and 72: Low-Expansion Borosilicate Glass Th
Page 73 and 74: ZERODUR ® Many optical application
Page 75 and 76: Optical Coatings 5 Optical Coatings
Page 77 and 78: OEM and Special Coatings Melles Gri
Page 79 and 80: PERCENT REFLECTANCE 100 90 80 70 60
Page 81 and 82: will depend on the ratio of optical
Page 83 and 84: v = angle of incidence PERCENT REFL
Page 85 and 86: PERCENT REFLECTANCE PER SURFACE 2.0
Page 87 and 88: Two-Layer Coatings of Arbitrary Thi
Page 89 and 90: ION-ASSISTED BOMBARDMENT Ion-assist
Page 91 and 92: Single-Layer MgF 2 Antireflection C
Page 93 and 94: PERCENT REFLECTANCE 5 4 3 2 1 norma
Page 95 and 96: EXTENDED-RANGE HEBBAR ANTIREFLECTIO
Page 97 and 98: V-Coatings V-coatings are multilaye
Page 99: Metallic High-Reflection Coatings W
Page 103 and 104: Dielectric High-Reflection Coatings
Page 105 and 106: PERCENT REFLECTANCE 100 80 60 40 20
Page 107 and 108: MAXBRIte Coatings MAXBRIte (multi
Page 109 and 110: Laser-Line MAX-R Coatings These mu
Page 111 and 112: Ultrafast Coating Melles Griot has
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Optical Coatings

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