Navigation Path:
OPTICS / LENSES / Spherical Bi-Convex Lenses
Converging Lenses (Positive Lenses): Thicker in the middle, they cause parallel light rays to converge to a single focal point.
Biconvex Lenses: Both surfaces are convex with the same radius of curvature.
Applications include: Imaging and Magnification; Microscopy – used as objective lenses or eyepieces; Laser Focusing – used to focus laser beams to a small spot for applications like laser cutting, engraving, welding, drilling; Optical Systems for free-space Fiber Optics coupling
While it has Strong Converging Power, Single biconvex lens suffers from significant spherical aberration. Combined with other lens types (plano-concave or biconcave lenses), their positive spherical aberration can be strategically balanced.
POL-BCX SERIES
3.1) Laser Line Bi-Convex Lenses
Biconvex lens with BK7 glass or Corning UVFS glass based. Double surfaces with specific AR coated to work as focusing or special imaging systems.
The key difference lies in the anti-reflection (AR) coating. Standard lenses have a broadband AR coating that works over a wide range of wavelengths, like the entire visible spectrum. A laser line lens, however, features a laser line V-coating that is meticulously engineered to achieve near-perfect transmission (less than 0.25% reflection) at one or two specific wavelengths. This creates a “V” shaped dip in the reflection curve at the design wavelength. This coating dramatically increases the amount of light that passes through the lens and minimizes reflections that could damage the lens or create unwanted stray light in the system.
3.2) UVFS Bi-Convex Lenses (Uncoated)
UV fused silica features excellent UV Transmission unlike other common optical glasses like N-BK7; very low coefficient of thermal expansion. It’s highly stable and its optical properties won’t change significantly with temperature fluctuations. The extreme purity of UVFS eliminates microscopic defects that could be damaged by high-power lasers. UVFS doesn’t fluoresce under UV light, preventing unwanted light emissions that could interfere with sensitive measurements.
Applications suitable for: UV Laser Systems, Imaging Systems, Spectroscopy, High-Energy Physics.
Both surfaces of bi-convex lenses are spherical and have the same radius of curvature, minimizing aberrations in situations where the object and image distances are equal or nearly equal. As a guideline, bi-convex lenses are the best choice for minimizing aberrations if the conjugate ratio (object distance : image distance) is between 5:1 and 1:5. Outside this range, plano-convex lenses are usually preferred.
3.3) DIA25.4mm BK7 Bi-Convex Lenses AR@400-750nm
A bi-convex lens made from N-BK7 is a very common and versatile type of lens in optical systems. N-BK7 is the most widely used optical glass for high-quality components due to its excellent properties and cost-effectiveness. It is a type of borosilicate crown glass.
It features High Homogeneity, Good Transmission (from about 350 nm to 2000 nm), Cost-Effective (compared to specialized materials like UV fused silica, N-BK7 is significantly more affordable). However it’s not the best choice for extreme applications. E.g. it has higher coefficient of thermal expansion than UV fused silica, making it more sensitive to temperature changes. It also doesn’t transmit as well in the deep UV range.
A 400nm to 700nm AR coating is a broadband anti-reflection (BBAR) coating to increase light transmission and reduce reflections from the surfaces of a lens. When light hits an uncoated lens, approximately 4% of it is reflected at each air-to-glass surface. For a lens with two surfaces, this results in a total loss of about 8% of the light.
3.4) DIA25.4mm BK7 Bi-Convex Lenses AR@600-1100nm
A bi-convex lens made from N-BK7 is a very common and versatile type of lens in optical systems. N-BK7 is the most widely used optical glass for high-quality components due to its excellent properties and cost-effectiveness. It is a type of borosilicate crown glass.
It features High Homogeneity, Good Transmission (from about 350 nm to 2000 nm), Cost-Effective (compared to specialized materials like UV fused silica, N-BK7 is significantly more affordable). However it’s not the best choice for extreme applications. E.g. it has higher coefficient of thermal expansion than UV fused silica, making it more sensitive to temperature changes. It also doesn’t transmit as well in the deep UV range.
The 600-1100nm coating is typically a multi-layer dielectric coating that uses thin layers of different materials to achieve destructive interference for a broad range of wavelengths. While a V-coat is optimized for a single, narrow wavelength, a BBAR coating like this one balances performance across a much wider band.
3.5) DIA50.8mm BK7 Bi-Convex Lenses
Fabricating large bi-convex lenses is significantly more difficult than making smaller ones, primarily due to the challenges in handling, manufacturing, and metrology. i.e Substrate Shaping and Grinding, Polishing, Coating, ensuring consistent Thermal and Mechanical Stress
Measuring the optical quality of a large lens is often the most significant challenge. Standard interferometers used to measure surface flatness and figure have apertures that are typically much smaller than a large lens. This means a technician must take multiple measurements and stitch them together, a process that can introduce errors and may not accurately capture larger-scale surface deviations. Specialized, larger metrology equipment is required, which adds to the overall cost and complexity of the process.
3.6) Non-Standard Bi-Convex Lenses
Uncommon sizing and focal lengths, build for special projects that we have worked with our customers and partners.