Biconcave Lens – Precision Diverging Lenses for Optical Applications
What is a Biconcave Lens?
A biconcave lens, also known as a double concave lens, has two inward-curved (concave) surfaces. It is a diverging lens that spreads incoming parallel light rays outward, forming virtual, upright, and reduced images. Biconcave lenses are commonly used in laser beam expansion, optical instruments, and image reduction systems.
At Bote Optics, we provide custom-manufactured biconcave lenses with a focus on precision, coating versatility, and rapid global delivery.
Key Specifications – Biconcave Lens
Parameter
Specification Range
Material
BK7, Fused Silica, Sapphire, CaF₂, ZnSe
Diameter
5 mm – 100 mm (custom sizes)
Focal Length
-10 mm to -500 mm
Thickness Tolerance
±0.1 mm
Surface Quality
40-20 or 20-10 scratch-dig
Coating Options
Uncoated, AR, UV, VIS, NIR, IR
Surface Accuracy
λ/4 to λ/10
📌 Need a biconcave lens for high-power IR lasers or broadband AR coatings? Request a custom quote.
Double Concave Lens Definition
A double concave lens is a type of lens with both surfaces curved inward. It is classified as a negative lens due to its diverging property. This lens is used to spread light rays apart, which makes it useful in reducing optical aberrations, controlling beam diameter, or creating virtual images.
Double Concave Lens Ray Diagram
In a ray diagram of a biconcave lens:
Parallel rays diverge after passing through the lens.
Their extensions appear to originate from the focal point on the same side as the incoming light.
Image: Double Concave Lens Ray Path – Divergence of Incident Parallel Rays
Double Concave Lens Uses
Application
Purpose
Beam Expansion Systems
Widening laser beams
Optical Systems Alignment
Reducing focal shift and distortion
Imaging Systems
Minimizing magnification
Ophthalmic Equipment
Vision testing & correction
Microscopy & Projection Devices
Adjusting focal planes
🔬 Engineers at Bote work closely with customers to optimize biconcave lenses for specific system integration.
Double Concave Lens Image Characteristics
Type of Image: Always virtual
Orientation: Upright
Size: Reduced
Image Position: On the same side as the object
This makes biconcave lenses essential for systems that require non-inverted, smaller images such as VR optics and laser projectors.
Focal Length of Double Concave Lens
The focal length fff of a biconcave lens is negative and is calculated using the lensmaker’s formula: 1f=(n−1)(1R1−1R2)\frac{1}{f} = (n – 1)\left(\frac{1}{R_1} – \frac{1}{R_2}\right)f1=(n−1)(R11−R21)
For a symmetrical biconcave lens: f=−R2(n−1)f = \frac{-R}{2(n – 1)}f=2(n−1)−R
Where:
RRR = Radius of curvature (negative for concave surfaces)
nnn = Refractive index
💡 Tip: Contact Bote for help selecting the right focal length based on your optical path length and divergence angle.
A Hollow Double Concave Lens?
While most double concave lenses are solid glass or crystal, some experimental or fluidic systems use hollow lenses (filled with gases or liquids) to simulate unique refractive environments. Bote focuses on high-stability, solid optics with robust coatings for laser-grade use.
🔍 Need IR-compatible biconcave lenses (e.g., ZnSe, Ge)? Let us know your wavelength range!
FAQs – Biconcave Lenses
Q1: How do you define a concave lens? A: A concave lens is a diverging lens with at least one inward-curved surface. It spreads incoming light rays and forms virtual images.
Q2: What’s unique about a double concave lens image? A: The image is always virtual, upright, and smaller than the object. Ideal for image reduction applications.
Q3: What is a hollow double concave lens used for? A: These are used in fluid optics or experimental setups where refractive index control is needed dynamically.
Q4: Can I get a biconcave lens with custom coatings? A: Yes, at Bote, we offer custom AR coatings for UV, VIS, NIR, and IR ranges.
Q5: How do I choose between plano concave and biconcave? A: If you need symmetrical divergence and better spherical aberration control, go with biconcave.
Why Choose Bote for Biconcave Lenses?
🧪 In-house Optical Design and Testing
🏭 Full Manufacturing from Substrate to Coating
🌍 Singapore-based Export Logistics & Global Service
To provide the best experiences, we use technologies like cookies to store and/or access device information. Consenting to these technologies will allow us to process data such as browsing behavior or unique IDs on this site. Not consenting or withdrawing consent, may adversely affect certain features and functions.
Functional
Always active
The technical storage or access is strictly necessary for the legitimate purpose of enabling the use of a specific service explicitly requested by the subscriber or user, or for the sole purpose of carrying out the transmission of a communication over an electronic communications network.
Preferences
The technical storage or access is necessary for the legitimate purpose of storing preferences that are not requested by the subscriber or user.
Statistics
The technical storage or access that is used exclusively for statistical purposes.The technical storage or access that is used exclusively for anonymous statistical purposes. Without a subpoena, voluntary compliance on the part of your Internet Service Provider, or additional records from a third party, information stored or retrieved for this purpose alone cannot usually be used to identify you.
Marketing
The technical storage or access is required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes.
