Optical Mirrors are designed to reflect incident light for laser and imaging applications such as beam steering, interferometry, illumination, and more. Industries that utilize Optical Mirrors are bio-medical, life sciences, astronomy, metrology, semiconductor, and more. Mirrors designed for the optical laboratory are produced by a metal or dielectric coating on the polished surface by vacuum deposition.
Optical characteristics of reflectance with a variety of features are provided with the coating.
Types of Coats for Mirror Lens:
- Metallic Coating
- Broadband dielectric multi-layer
- Dielectric multi-layer coating
This diagram above depicts the usage of mirrors in CO2 laser machines and how it directs the laser source through the head for laser cutting and marking machines . With varying types of mirrors needed for different type of laser sources ( type of laser sources are UV, fibre and CO2). The different effectiveness of mirrors can be seen from the graph above with the type of mirror coatings and details of them below.
What is a metallic coated mirror lens?
Metalised mirrors are ideal for broadband applications like Spectroscopy and are useful in the UV, Visible and NIR ranges in a variety of industries. Dielectric coating layers are incorporated on top of the metallics to protect the surfaces and enhance the reflectivities. Metallic mirrors are generally lower in price compared to their dielectric counterparts and they are also polarisation insensitive.
Good reflectance in a wide range. As well as light absorption coating, this slightly reduces the reflection.
How Metallic Coating Mirror Lens is used:
They are designed for any simple optical system. Works well with low power lasers. Together with imaging optics that uses a white light illumination system. Also highly compatible when used together with infra-red optics.
Aluminium mirrors are often used in applications that are not highly demanding and are lower cost vs. Dielectric Mirrors. Aluminium Mirrors are also polarization independent. Therefore, they will operate at virtually any angle of incidence.
Dielectric Mirrors, also known as Bragg Mirrors consist of multiple layers of dielectric coating materials deposited onto glass surfaces typically. There exists a wide variety of dielectric mirrors that are appropriate for high power lasers, broadband light sources in a variety of applications.
Broadband Dielectric Coating Broadband Dielectric Coating
Dielectric Mirrors Features:
- High reflectance with low loss
- The coating has zero absorption with high laser strength
- It is resistant to hard scratches
- Designed and manufactured for a narrow wavelength range
- It is used at 45 degree angle of incidence
Broadband Dielectric Multi-layer:
This section may be titled Broadband Dielectric Mirrors, although, you will also see these named Ultra-Broadband Dielectric Mirrors and the ranges are incredibly wide, with high reflectance throughout. With UV mirrors from 245nm-400nm and UV to NIR from 300nm-2000nm. Reflectance values up to 98% average across the bands. These are specific for use at 45-Degree AOI and are suitable for applications that require high reflectance across a broad spectrum
- Designed for precision optical systems especially for low light and low loss optical systems.
- Sub-watt class laser systems
- Multi-wavelength laser optical systems
Dielectric multi-layer coating:
Generally used for high powered laser system
- Laser Line Mirrors:
- These Laser Line Dielectric Mirrors are suitable for demanding laser applications. You will find a variety of sizes starting at 12.7mm diameters, up to 50.8mm and specific wavelength mirrors starting from the Ultraviolet, 157nm, up to Nd: YAG, 1064nm. Our substrates are highly polished to 10/5 Scratch Dig and Surface Flatness, λ/10. Additionally, these offer high laser damage thresholds up to 20J/cm2.
- Wide Angle Dielectric Mirrors:
- This family of Dielectric Mirrors are specified for use from 0-45 Degree AOI with reflectance values of Ravg>99%. They range in size from 10mm round to 50mm and in wavelengths from 405nm to 1550nm. These are also suitable for demanding laser applications and substrates are polished to a flatness of λ/10 and 10/5 Scratch Dig.
- High Power Mirrors:
- This section contains a variety of High Power Yb Dielectric Mirrors. Wavelengths from 257nm, 343nm, 515nm & 1030nm and in sizes from 12.7mm to 50.8mm in diameter. The substrate material is Fused Silica for low thermal expansion, and they are polished to a flatness of λ/10 and 10/5 Scratch Dig. The laser damage thresholds go up to 28J/cm2.
Mirrors with a dielectric multi-layer coating can have a variety of features in addition to the characteristics of reflectance
This can be seen from the two mirrors below. Both with different attributes but have dielectric multi-layer coating