UV Mirrors: Reflecting the Future of Optical Systems

Author: Bryan Ng – Marketing Manager

Editor: Qu Yingli – R&D Director

Published on:

Last edited:

1. Understanding UV Mirrors

Optical mirrors have reflective surfaces that can reflect light and are typically used to fold or compact an optical system. UV Mirrors are specialized mirrors made to reflect ultraviolet (UV) light. These types of mirrors are commonly used in different applications such as medical imaging, semiconductor manufacturing, fluorescence microscopy, and even astronomy.

UV mirrors require the selection of specific materials and coatings. The different applications of UV reflectivity of mirrors vary at different wavelengths due to a combination of factors, such as the substrate material, thickness and composition of coatings, and the angle of incidence. Understanding and assessing how these factors affect the properties of UV light is critical to designing mirrors for specific applications.

2. Applications of UV Mirrors

2.1 Medical Industry

UV mirrors have a broad application scope in the medical field. In medical imaging, there are various imaging techniques, such as fluorescence microscopy, that rely on UV fluorescence. This enhances the visualization of specific biological markers and assists in the diagnosis of diseases. Other uses of such mirrors include UV sterilization of medical equipment and the curing of dental materials in dentistry.

2.2 Semiconductor Manufacturing

The semiconductor industry relies on UV mirrors for photolithography processes, a crucial step in manufacturing integrated circuits. UV mirrors are used for the precise patterning of silicon chips, by directing and focusing ultraviolet light onto photoresist-coated semiconductor wafers. This ensures the production of smaller and more efficient electronic components.

2.3 Laser Systems

Various UV Laser systems utilize UV mirrors to steer UV light. These lasers range from relatively low-powered lasers used in LASIK surgery to much higher-power lasers used in security. Depending on the laser power and frequency, specialized UV mirrors may be required for such applications. For example, a higher-powered laser may require a mirror that has a higher heat tolerance and can dissipate heat quickly, while a mirror used in more precise applications such as LASIK eye surgery would require a higher surface quality.

3. Types of UV Mirrors

Different types of UV Mirrors can be differentiated using their constituent materials and manufacturing processes. The most common UV mirrors are dielectric mirrors or metal-coated mirrors. UV mirrors may also be differentiated by the application that they are designed for. These are often customized versions of dielectric mirrors and metal-coated mirrors, with varying substrates, coatings, thicknesses, and manufacturing processes. Some commonly used types of mirrors are laser line mirrors and ultrafast mirrors.

3.1 Broadband Dielectric Mirrors

Optical Mirrors Broadband Mirrors
Wavelength Opto-Electronic Broadband Dielectric Mirrors

Material: BK7 or Fused Silica
Dimension Tolerance: +0.0/-0.2mm
Thickness Tolerance: ±0.2mm
Surface Quality: 20/10 S-D
Clear Aperture: >90%
Reflectance: >99%
Angle of Incidence: 45°
Flatness: < λ/10 @ 632.8nm per 25mm range
Chamfer: Protective<0.5mmx45°
Coating: Dielectric HR
Damage Threshold: >5J/cm², 20ns, 20Hz, @1064nm

Specifications 1: Wavelength Opto-Electronic Broadband Dielectric Mirrors

Broadband dielectric mirrors are designed to demonstrate high reflectivity across a broad range of wavelengths within the electromagnetic spectrum. In contrast with conventional mirrors that are optimized for reflection at a given wavelength or in a narrow spectral band, broadband dielectric mirrors are designed to reflect light efficiently across a wide range of frequencies including the UV, visible, and infrared (IR) range.

Part NumberWavelength (nm)Dimension (mm)Thickness (mm)MaterialReflectivity (%)
RFS-1-6.35-B1350 – 40025.46.35Fused Silica> 99
RFS-30-5-B1350 – 40030.05.00Fused Silica> 99
RFS-1.5-6.35-B1350 – 40038.16.35Fused Silica> 99
RFS-1.5-9.5-B1350 – 40038.19.50Fused Silica> 99
RFS-2-9.5-B1350 – 40050.89.50Fused Silica> 99
Table 1: Wavelength Opto-Electronic Standard Broadband Dielectric UV Mirrors

These mirrors are made by depositing multiple dielectric materials with varying refractive indices onto a substrate. The arrangement and thickness of these materials create interference effects that increase the reflectance of the mirror across a broad spectrum. This makes it possible to customize the mirror depending on particular applications and needs. They are more robust and resilient to environmental forces than metal-coated mirrors. However, the manufacturing process is not as straightforward which makes it a more costly product in production compared to its metal-plated counterpart.

3.2 Metal-Coated Mirrors

Optical Mirrors Broadband Metallic Mirrors
Wavelength Opto-Electronic Broadband Metallic Mirror

Material: BK7 or Fused Silica
Dimension Tolerance: +0.0/-0.2mm
Thickness Tolerance: ±0.2mm
Surface Quality: 20/10 S-D
Clear Aperture: >90%
Angle of Incidence: 45°
Flatness:  < λ/10 @ 632.8nm
Protected Aluminium: Ravg>90% @ 400nm-2µm
Protected Silver: Ravg>97% @ 400nm-2µm
Damage Threshold: >1 J/cm², 20ns, 20Hz, @1064nm

Specifications 2: Wavelength Opto-Electronic Broadband Metallic Mirrors

Metal-coated UV mirrors are produced by coating a suitable substrate with a thin layer of metallic film of aluminum or silver using various techniques such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). Aluminium and Silver are two common metals used for coatings in such mirrors. Aluminum-coated mirrors are cost-effective and widely used for UV applications, as they exhibit excellent reflectivity. However, aluminum coatings can be susceptible to oxidation over time, which may affect their reflective performance. Such mirrors need frequent maintenance and precautions to preserve their reflective nature.

Part NumberWavelengthDimension (mm)Thickness (mm)MaterialReflectivity (%)
RFS-1-6.35-A450 nm – 20 µm25.46.35Fused Silica> 90% @ 450nm – 2µm
RFS-30-5-A450 nm – 20 µm30.05.00Fused Silica> 90% @ 450nm – 2µm
RFS-1.5-6.35-A450 nm – 20 µm38.16.35Fused Silica> 90% @ 450nm – 2µm
RFS-1.5-9.5-A450 nm – 20 µm38.19.50Fused Silica> 90% @ 450nm – 2µm
RFS-2-9.5-A450 nm – 20 µm50.89.50Fused Silica> 90% @ 450nm – 2µm
RFS-1-6.35-S450 nm – 20 µm25.46.35Fused Silica> 97% @ 450nm – 2µm
RFS-30-5-S450 nm – 20 µm30.05.00Fused Silica> 97% @ 450nm – 2µm
RFS-1.5-6.35-S450 nm – 20 µm38.16.35Fused Silica> 97% @ 450nm – 2µm
RFS-1.5-9.5-S450 nm – 20 µm38.19.50Fused Silica> 97% @ 450nm – 2µm
RFS-2-9.5-S450 nm – 20 µm50.89.50Fused Silica> 97% @ 450nm – 2µm
Table 2: Wavelength Opto-Electronic Standard Broadband Metallic Mirrors

UV mirrors may also be differentiated by the application that they are designed for. These are often customized versions of dielectric mirrors and metal-coated mirrors, with varying substrates, coatings, thicknesses, and manufacturing processes. Some commonly used types of mirrors are laser line mirrors and ultrafast mirrors.

3.3 Laser Line Mirrors

Laser Optics - Optical Mirrors - Laser Line Mirrors
Wavelength Opto-Electronic Laser Line Mirrors

Substrate Material: N-BK7 & Fused Silica
Dimension Tolerance: +0.0/-0.25mm
Thickness Tolerance: ±0.25mm
Surface Quality: 10/5 S-D
Clear Aperture: >90%
Reflectance: >99% at 45°
Angle of Incidence: 0-45°
Flatness: < λ/10 @ 632.8nm
Group Delay Dispersion: < 30fs² (for s & p-polarized light)
Coating: HR @ 350-400nm / 510-580nm / 950-1150nm
Damage Threshold @ 20ns, 20Hz: 20 J/cm2 for 1064nm / 15 J/cm2 for 532nm / 10 J/cm2 for 355nm

Specifications 3: Wavelength Opto-Electronic Laser Line Mirrors

Laser line mirrors are ideal for applications that require the reflection or redirection of laser beams, particularly in tasks like beam steering or beam folding. These mirrors are designed with higher damage thresholds for high-power lasers. These mirrors are commonly used for neodymium YAG lasers, but may also be customized for lasers within the UV spectrum.

Part NumberWavelength (nm)Dia (mm)ET (mm)MaterialReflectivity (%)
RFS-0.75-3.2U35519.13.2Fused Silica99.5
RFS-0.75-9.5U35519.19.5Fused Silica99.5
RFS-20-2U355202Fused Silica99.5
RFS-1-3U35525.43Fused Silica99.5
RFS-1-6U35525.46Fused Silica99.5
RFS-1-6.3U35525.46.3Fused Silica99.5
RFS-1-9.5U35525.49.5Fused Silica99.5
RFS-30-5U35530.15Fused Silica99.5
RFS-1.5-3U35538.13Fused Silica99.5
RFS-1.5-9.5U35538.19.5Fused Silica99.5
RFS-38.5-3U35538.53Fused Silica99.5
RFS-50-5U355505Fused Silica99.5
RFS-2-6.3U35550.86.3Fused Silica99.5
RFS-2-9.5U35550.89.5Fused Silica99.5
RFS-1-9.5V26625.49.5Fused Silica99.5
RFS-30-5V266305Fused Silica99.5
RFS-1.5-9.5V26638.19.5Fused Silica99.5
RFS-2-9.5V26650.89.5Fused Silica99.5
Table 3: Wavelength Opto-Electronic Standard Laser Line Mirrors

3.4 Ultrafast Mirrors

Optical Mirrors - Ultrafast Mirrors - Focusing Lenses - Medical Laser Lenses
Wavelength Opto-Electronic Ultrafast Mirror

Material: Fused Silica
Dimension Tolerance: +0.0/-0.2mm
Thickness Tolerance: ±0.2mm
Surface Quality: 20/10 S-D
Clear Aperture: >80%
Reflectance: >99%
Angle of Incidence: 45°
Flatness: < λ/10 @ 632.8nm
Group Delay Dispersion: < 30fs² (for s & p-polarized light)
Coating: HR
Damage Threshold: >100mJ/cm² @ 800nm, 50fs, 50Hz

Specifications 4: Wavelength Opto-Electronic Ultrafast Mirrors

Ultrafast mirrors are designed to accommodate ultrafast lasers. These are lasers that emit ultrashort pulses, i.e light pulses with durations of femtoseconds or picoseconds. These mirrors have high damage thresholds and a low Group Dispersion Delay (GDD). GDD is a measure of how much different frequencies within a pulse are delayed relative to each other. A low GDD mirror is essential when the management of the temporal characteristics of ultrashort laser pulses is critical.

Ultrafast Mirrors Diagram 2
Figure 3: Ultrafast Mirrors GDD @ 355-455nm

The graph shown above is for a fused silica ultrafast mirror. As shown, the mirror has a GDD of less than 30fs² (for s & p-polarised light), between 370nm and 420nm. This property makes such mirrors very useful in areas such as spectroscopy, material processing, and the medical industry.

Part NumberWavelength (nm)Dimension (mm)Thickness (mm)MaterialGroup Delay Dispersion
RFS-1-6.35-UM1355 – 45525.46.35Fused Silica< 30 fs²
RFS-30-5-UM1355 – 45530.05.00Fused Silica< 30 fs²
RFS-1.5-6.35-UM1355 – 45538.16.35Fused Silica< 30 fs²
RFS-1.5-9.5-UM1355 – 45538.19.50Fused Silica< 30 fs²
RFS-2-9.5-UM1355 – 45550.89.50Fused Silica< 30 fs²
Table 4: Wavelength Opto-Electronic Standard Ultrafast Mirror

4. Looking for a Reliable UV Mirrors Supplier?

With our state-of-the-art facilities and vast experiences, Wavelength Opto-Electronic designs and manufactures quality optical mirrors including UV mirrors that comes in different geometries and coating options. While off-the-shelves solutions are readily available (as shown in the above product tables), we’re also able to customize UV mirrors from standard to high precision specifications and utilize different optical materials from glass, crystal to metal.

ToleranceStandardPrecisionHigh Precision
SubstratesGlass: N-BK7, Fused Silica
Crystal:  ZnSe,  Si
Metal: Cu, Al, Mo
DimensionsMinimum: 4 mm, Maximum: 200 mm
Shapes/GeometriesElliptical, Flat, Spherical, Parabolic
Dimension±0.25mm±0.1mm±0.05mm
Thickness±0.1mm±0.05mm±0.01mm
Wavelength Range350nm-20μm350nm-20μm350nm-20μm
Flatnessλ/4λ/10
Reflectivity85%90%99.9%
Coating OptionsMetallic, Broadband Dielectric, Narrowband Dielectric,
Surface Quality80-5040-2010-5
Table 5: Wavelength Opto-Electronic Optical Mirrors Manufacturing Capabilities

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