Reference for selecting optical coated lenses
Reflective lenses are important components in optical experiments, and their quality, performance, and durability have a significant impact on success. Our company offers a variety of different reflective mirror products to ensure that customers can find products that are suitable for their applications. When choosing a reflector, it is important to consider parameters such as reflectivity, wavelength range, laser damage threshold, and durability of the coating. We have long-term inventory of many common models of lenses to achieve fast supply.
Coating type
Broadband metal coating
Metal coated mirrors are an economical and practical choice for most applications, with a wide range of wavelengths typically ranging from 450 nm-12 μ m; m， And they are insensitive to the polarization state and incident angle of light, with relatively small phase shifts at different wavelengths, making them suitable for ultra short pulse applications. However, metal coatings are generally fragile and easily damaged, so special attention should be paid when cleaning.
Broadband and laser dielectric coating
Broadband dielectric coating can provide high reflectivity in the range of several hundred nanometers, and is more durable, easy to clean, and has a higher laser damage threshold. We have multiple series of broadband dielectric coated mirror products, as well as dielectric coated mirrors specially designed for different laser wavelengths, such as 1064 nm and 532 nm wavelengths for high-power Nd: YAG lasers, and wavelengths for excimer lasers in the DUV and UV bands.
Ultra fast optical coating
Generally speaking, dielectric coating can cause severe dispersion in the broad spectrum of ultra short pulses. The interference effect between dielectric coating layers can cause rapid phase changes at different wavelengths, resulting in pulse broadening and distortion. Therefore, for applications that require maintaining ultra short pulse time domain width, it is advisable to choose specially designed mirrors coated with ultrafast optical media or silver coating to reduce dispersion.
base material
Borofloat® glass
Borofloat® Glass has good thermal stability and is easier to polish than fused silica. General Borofloat® The uniformity of the refractive index of glass is not very good, so it is not suitable for use in lens products that require transmission. Usually, the back of the substrate is frosted to eliminate a small amount of transmitted light. The edges of the substrate are generally polished to avoid scratches.
Zerodur® Has unparalleled thermal stability, with a coefficient of thermal expansion close to zero. When the temperature of the application environment fluctuates frequently, Zerodur® Base lenses are an excellent choice.
UV fused silica
UV grade fused silica is also a common reflector substrate. It also has excellent thermal stability. And its refractive index fraction
The fabric is very uniform and suitable for use in reflective lenses that require partial transmission.
Surface quality
The surface deviation of optical lenses is defined by the aperture Surface Power (Surface Figure) or surface flatness, as well as the local aperture Surface Irregularity. Aperture Surface Power for Spherical Components
Figure refers to the deviation between the curvature radius of the lens surface and the ideal spherical or reference surface curvature radius, while Surface Flatness only applies to planes, representing the deviation between the component plane and the ideal plane. Both flat and spherical surfaces can be expressed in terms of aperture or surface flatness. Surface Irregularity IRR represents the surface of an optical element in relation to an ideal plane or reference optics
Local irregularity generated in any direction on the surface. Usually, the front surface of the lenses we provide has a≤&lambda/ 10@633 The surface flatness of nm. When the application has very strict requirements for wavefront distortion, please choose to haveλ /Lens with a surface flatness of 10 or less.
Surface Quality is another requirement for the surface quality of optical components, specifically the scratches and dents on the optical surface. Newport strictly controls the maximum allowable surface defects on the optical surface according to the US military standard MIL-PRF-13830B. The surface smoothness parameters of the lenses we provide are in the range of 60-40 to 10-5. The smaller the value, the smaller the size and quantity of scratches and dents. High surface finish lenses are particularly important for laser, ultraviolet, or deep ultraviolet applications, as they can effectively reduce light scattering.
The definition of pockmarks: convex, concave, or spotted defects on the surface of a lens caused by polishing or coating. The parameter represents the average diameter size of the defect, measured in 10 micrometers; The unit is m.
Definition of scratch: A surface defect in the form of a linear or elongated shape, with an aspect ratio exceeding 4:1, defined by width and measured in micrometers; The unit is m.
Scratches and pitting are usually classified into several levels such as 10-5, 20-10, 40-60, 60-40, 80-50, etc.