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
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 Number | Wavelength (nm) | Dimension (mm) | Thickness (mm) | Material | Reflectivity (%) |
|---|---|---|---|---|---|
| RFS-1-6.35-B1 | 350 – 400 | 25.4 | 6.35 | Fused Silica | > 99 |
| RFS-30-5-B1 | 350 – 400 | 30.0 | 5.00 | Fused Silica | > 99 |
| RFS-1.5-6.35-B1 | 350 – 400 | 38.1 | 6.35 | Fused Silica | > 99 |
| RFS-1.5-9.5-B1 | 350 – 400 | 38.1 | 9.50 | Fused Silica | > 99 |
| RFS-2-9.5-B1 | 350 – 400 | 50.8 | 9.50 | Fused Silica | > 99 |
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
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 Number | Wavelength | Dimension (mm) | Thickness (mm) | Material | Reflectivity (%) |
|---|---|---|---|---|---|
| RFS-1-6.35-A | 450 nm – 20 µm | 25.4 | 6.35 | Fused Silica | > 90% @ 450nm – 2µm |
| RFS-30-5-A | 450 nm – 20 µm | 30.0 | 5.00 | Fused Silica | > 90% @ 450nm – 2µm |
| RFS-1.5-6.35-A | 450 nm – 20 µm | 38.1 | 6.35 | Fused Silica | > 90% @ 450nm – 2µm |
| RFS-1.5-9.5-A | 450 nm – 20 µm | 38.1 | 9.50 | Fused Silica | > 90% @ 450nm – 2µm |
| RFS-2-9.5-A | 450 nm – 20 µm | 50.8 | 9.50 | Fused Silica | > 90% @ 450nm – 2µm |
| RFS-1-6.35-S | 450 nm – 20 µm | 25.4 | 6.35 | Fused Silica | > 97% @ 450nm – 2µm |
| RFS-30-5-S | 450 nm – 20 µm | 30.0 | 5.00 | Fused Silica | > 97% @ 450nm – 2µm |
| RFS-1.5-6.35-S | 450 nm – 20 µm | 38.1 | 6.35 | Fused Silica | > 97% @ 450nm – 2µm |
| RFS-1.5-9.5-S | 450 nm – 20 µm | 38.1 | 9.50 | Fused Silica | > 97% @ 450nm – 2µm |
| RFS-2-9.5-S | 450 nm – 20 µm | 50.8 | 9.50 | Fused Silica | > 97% @ 450nm – 2µm |
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
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 Number | Wavelength (nm) | Dia (mm) | ET (mm) | Material | Reflectivity (%) |
|---|---|---|---|---|---|
| RFS-0.75-3.2U | 355 | 19.1 | 3.2 | Fused Silica | 99.5 |
| RFS-0.75-9.5U | 355 | 19.1 | 9.5 | Fused Silica | 99.5 |
| RFS-20-2U | 355 | 20 | 2 | Fused Silica | 99.5 |
| RFS-1-3U | 355 | 25.4 | 3 | Fused Silica | 99.5 |
| RFS-1-6U | 355 | 25.4 | 6 | Fused Silica | 99.5 |
| RFS-1-6.3U | 355 | 25.4 | 6.3 | Fused Silica | 99.5 |
| RFS-1-9.5U | 355 | 25.4 | 9.5 | Fused Silica | 99.5 |
| RFS-30-5U | 355 | 30.1 | 5 | Fused Silica | 99.5 |
| RFS-1.5-3U | 355 | 38.1 | 3 | Fused Silica | 99.5 |
| RFS-1.5-9.5U | 355 | 38.1 | 9.5 | Fused Silica | 99.5 |
| RFS-38.5-3U | 355 | 38.5 | 3 | Fused Silica | 99.5 |
| RFS-50-5U | 355 | 50 | 5 | Fused Silica | 99.5 |
| RFS-2-6.3U | 355 | 50.8 | 6.3 | Fused Silica | 99.5 |
| RFS-2-9.5U | 355 | 50.8 | 9.5 | Fused Silica | 99.5 |
| RFS-1-9.5V | 266 | 25.4 | 9.5 | Fused Silica | 99.5 |
| RFS-30-5V | 266 | 30 | 5 | Fused Silica | 99.5 |
| RFS-1.5-9.5V | 266 | 38.1 | 9.5 | Fused Silica | 99.5 |
| RFS-2-9.5V | 266 | 50.8 | 9.5 | Fused Silica | 99.5 |
3.4 Ultrafast Mirrors
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.
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 Number | Wavelength (nm) | Dimension (mm) | Thickness (mm) | Material | Group Delay Dispersion |
|---|---|---|---|---|---|
| RFS-1-6.35-UM1 | 355 – 455 | 25.4 | 6.35 | Fused Silica | < 30 fs² |
| RFS-30-5-UM1 | 355 – 455 | 30.0 | 5.00 | Fused Silica | < 30 fs² |
| RFS-1.5-6.35-UM1 | 355 – 455 | 38.1 | 6.35 | Fused Silica | < 30 fs² |
| RFS-1.5-9.5-UM1 | 355 – 455 | 38.1 | 9.50 | Fused Silica | < 30 fs² |
| RFS-2-9.5-UM1 | 355 – 455 | 50.8 | 9.50 | Fused Silica | < 30 fs² |
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.
| Tolerance | Standard | Precision | High Precision |
| Substrates | Glass: N-BK7, Fused Silica | ||
| Crystal: ZnSe, Si | |||
| Metal: Cu, Al, Mo | |||
| Dimensions | Minimum: 4 mm, Maximum: 200 mm | ||
| Shapes/Geometries | Elliptical, Flat, Spherical, Parabolic | ||
| Dimension | ±0.25mm | ±0.1mm | ±0.05mm |
| Thickness | ±0.1mm | ±0.05mm | ±0.01mm |
| Wavelength Range | 350nm-20μm | 350nm-20μm | 350nm-20μm |
| Flatness | 2λ | λ/4 | λ/10 |
| Reflectivity | 85% | 90% | 99.9% |
| Coating Options | Metallic, Broadband Dielectric, Narrowband Dielectric, | ||
| Surface Quality | 80-50 | 40-20 | 10-5 |
