We use different transmissive Substrates in our production:

  • Crown Glass:

    • Advantages: Most resistant to scratches, low refractive index, high Abbe number (minimizes chromatic aberrations), good for visible and near-infrared applications.
    • Disadvantages: Heavy, may need chemical or heat treatment, some variations can suffer from corrosion.
    • Examples: Bi-convex lenses, windows, prisms.

  • Flint Glass:

    • Advantages: High refractive index (good for light bending), allows for compact lenses, some variations offer UV protection.
    • Disadvantages: Denser and heavier than crown glass, higher dispersion (chromatic aberrations), some variations have limitations on UV and IR transmission.
    • Examples: Flint glass plano-convex lenses, telescope lenses.

  • Float Glass:

    • Advantages: High light transmittance (visible and near-infrared), scratch-resistant, low thermal expansion, good chemical inertness.
    • Disadvantages: Can break at high temperatures, limited size for larger applications.
    • Examples: Flat windows, inspection panels.

  • Polymeric Substrates (Plastics):

    • Advantages: Lightweight, lower cost, easier to mold into complex shapes, good for visible applications.
    • Disadvantages: Lower optical quality than glass (higher dispersion, stress birefringence, less thermal stability).
    • Examples: Ophthalmic lenses (reading glasses, sunglasses), camera lenses (mobile phones, drones), optical storage devices (CDs, DVDs).

  • Fused Silica:

    • Advantages: High purity, excellent transmission across UV, visible, and IR spectrum, high thermal resistance, good chemical resistance.
    • Disadvantages: More expensive than glass, not ideal for high-power laser applications.
    • Examples: Lenses, mirrors, UV and IR optics, metrology components.

  • Other Substrates: Calcium Fluoride (CaF2), Quartz (SiO2), Zinc Selenide (ZnSe), Silicon (Si), Germanium (Ge), Sapphire (Al2O3), Magnesium Fluoride (MgF2), Black Diamond-2 (BD-2), Zinc Sulfide (ZnS). These are used for specific applications based on their unique properties like broader transmission ranges, high thermal conductivity, or resistance to harsh environments.

Our Reflective Substrates:

Many of the materials used for transmissive substrates can also be used for reflective systems, but with a reflective coating applied to the surface. 

  • Crown Glass and Fused Silica: Popular choices due to availability and cost-effectiveness.
  • Soda-Lime Glass: Can be used for specific applications like adjusting light transmission.
  • Aluminum: Offers broadband reflectivity but tarnishes more easily than silver.

Choosing the right substrate depends on the specific requirements of the optical system, such as:

  • Wavelength range of operation (UV, visible, IR)
  • Required level of transmission or reflection
  • Mechanical strength and stability
  • Thermal properties
  • Cost

We are using different coatings for our lenses. Here’s a breakdown of some common laser lens coatings we manufacture and their advantages:

  1. Anti-Reflection (AR) Coating:

    • Function: Minimises light reflection at a specific wavelength or range of wavelengths, allowing for higher light transmission through the lens.
    • Advantages:
      • Increases overall system efficiency by maximizing light power delivered to the target.
      • Reduces unwanted reflections that can cause ghost images or interfere with laser performance.
      • Can be customized for a specific wavelength range depending on the application.

  2. High Reflection (HR) Coating:

    • Function: Reflects light at a specific wavelength or range of wavelengths very efficiently, acting like a mirror.
    • Advantages:
      • Used in laser cavities to trap light and amplify the laser beam.
      • Directs laser light in a specific direction for applications like laser cutting or material processing.
      • Can be designed for broad or narrow reflection bandwidth depending on the need.

  3. Dichroic Coating:

    • Function: Acts like a wavelength filter, selectively reflecting specific wavelengths while transmitting others.
    • Advantages:
      • Used in beam splitters to separate different wavelengths of light from a single beam.
      • Can be used for laser pumping setups where a pump laser wavelength needs to be reflected towards the gain medium while the laser output wavelength transmits.
      • Offers flexibility for complex optical systems requiring wavelength filtering.

  4. Bandpass Filter Coating:

    • Function: Similar to a dichroic coating, but transmits a specific, narrow band of wavelengths while reflecting everything else.
    • Advantages:
      • Used for applications like laser cleaning or spectroscopy where only a specific wavelength range is needed.
      • Blocks unwanted stray light or background noise, improving signal-to-noise ratio.
      • Provides high transmission within the desired wavelength band.

  5. Anti-Reflective and Anti-Scattering (AR/AS) Coating:

    • Function: Combines the benefits of AR coating (minimizing reflection) with anti-scattering properties, reducing light scattering within the lens material.
    • Advantages:
      • Improves overall light transmission by minimizing both reflection and scattering losses.
      • Especially beneficial for high-power laser applications where scattering can be detrimental.
      • Maintains high image quality by reducing light diffusion within the lens.

These are some of the most common types of laser lens coatings. The specific choice depends on the application and desired outcome. For example, an AR coating would be ideal for a laser-focusing lens to maximise light transmission, while an HR coating would be crucial for a laser cavity mirror to reflect light and amplify the beam.

Thin film applied to an optical component designed to manipulate light around the 600 to 2100 nanometer (nm) wavelength. There are two main possibilities for this type of coating:

  1. High Reflection (HR) Coating: This coating reflects light at the 600 to 2100nm wavelength very efficiently, bouncing it back with minimal absorption. It essentially acts like a mirror for this specific wavelength. 

  2. HR coatings for 2100nm are often used in conjunction with Holmium:Yttrium Aluminum Garnet (Ho:YAG) lasers, a type of laser commonly used in medical applications due to its shallow penetration depth in tissue.

  3. Anti-Reflection (AR) Coating: This coating, in contrast, minimizes reflection at the 600 to 2100nm wavelength, allowing light to pass through the coated surface with minimal loss. AR coatings for 2100nm might be used for lenses or windows in instruments designed to work with Ho:YAG lasers, ensuring optimal light transmission.

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