Custom Optical Filters: A Buyer's Guide for OEM and Integrators
Oct 29,2026 | JINGYU OPTOELEC
Optical filters are specified, not shopped. Unlike a gobo, nobody buys a dichroic filter because the listing looked nice — they buy it against a coating curve, a substrate, and a tolerance. Which means the supplier conversation is won or lost on how precisely you can describe the requirement, and how fast the supplier can come back with a real answer.
This guide covers what to specify, what drives cost, and the four numbers to send in your first email.
The five filter families, and what each is for
|
Type |
Function |
Typical application |
|
Bandpass / dichroic |
Passes a wavelength band, reflects the rest |
Color separation, sensors, lighting |
|
Longpass / shortpass |
Passes above or below a cut-on wavelength |
Laser separation, edge filters |
|
AR coating (anti-reflective) |
Reduces surface reflection |
Lenses, windows, display covers |
|
IR / UV cut |
Blocks infrared or ultraviolet |
Imaging, beauty devices, thermal protection |
|
Reflective mirror / beam combiner |
Redirects or combines beams |
Laser optics, projection systems |
Each family has its own tolerance language. A "good" spec for an AR window is meaningless for a bandpass filter.
What to specify (the four numbers)
Suppliers can quote a price from almost nothing, but they cannot quote an accurate one. Send these four and the reply becomes a real specification instead of a question:
1. Substrate and thickness. BK7, B270, fused silica, sapphire, or soda-lime. Fused silica and sapphire survive high power and harsh environments; BK7 is the economical default. Thickness is not cosmetic — it shifts the optical path and affects wavefront error.
2. Dimensions and tolerance. Diameter or rectangular size, plus tolerance (±0.1 mm is common). Square-cut windows with tight corner tolerances cost more than round.
3. Optical specification. For a bandpass: center wavelength, bandwidth (FWHM), and blocking range. For AR: the wavelength range and target reflectance per surface. For a mirror: reflectivity at the design angle, and the angle range.
4. Quantity and surface quality. Scratch-dig (e.g. 60-40 or 40-20) and quantity. Surface quality and quantity move price more than any other pair of parameters.
A first email containing these four gets a technical reply. An email saying "we need an optical filter, please quote" gets a request for the same four — and a week lost.
What drives the price
Coating complexity. A single-layer AR is inexpensive. A 40-layer dichroic stack is not. Every additional layer is deposition time and yield risk.
Tolerance. Tightening wavelength tolerance from ±10 nm to ±2 nm typically costs 30–100% more, because yield drops.
Substrate. Sapphire and fused silica cost multiples of soda-lime, and large-format fused silica is often on lead time.
Size. Cost scales faster than area. A 100 mm window is not 4× a 50 mm window — handling and coating uniformity push it higher.
MOQ. Small runs carry setup cost per batch. This is where a factory-direct supplier differs most from a catalog distributor: MOQ is negotiable, and small prototyping runs are possible.
Prototype first, then scale
The failure mode in custom optics is ordering production quantity against an unverified design. Recommended sequence:
- Specification review — send the four numbers, get feasibility and a coating curve
- Prototype run — 5–20 pieces, measure, iterate
- Production — quantity pricing after the design is proven
Skipping step 2 is how projects end up with 5,000 parts that miss the spec by one parameter.
Quality documentation to ask for
- Coating curve / transmission data for the delivered batch, not a generic datasheet
- Inspection report — dimensions, scratch-dig, coating adhesion
- Environmental test results if the part goes outdoors or into a medical device
- RoHS / REACH declarations for consumer products
If a supplier cannot provide batch-level data, they are trading, not manufacturing.
Two adjacent categories worth knowing
Beauty device filters follow the same rules but with a consumer-safety overlay: IR/UV cut specifications matter for skin-contact devices, and documentation requirements are stricter.
Laser protective lenses are a safety component, not a convenience one. Specify the wavelength, the optical density required, and the power level — and never substitute a general-purpose filter for a rated protective window.
Frequently asked questions
What is the minimum order for custom filters? Prototype runs from small quantities are usually possible with a factory-direct supplier. Production pricing typically starts to improve meaningfully above a few hundred pieces.
Can you match an existing filter's performance? Yes, if you can supply the transmission curve or the original part's specification. Send a sample if documentation is unavailable.
How long does a custom coating run take? Prototypes in 1–2 weeks; production typically 3–5 weeks depending on coating complexity and substrate availability.
Do you provide coating curves with the shipment? Yes, batch-level transmission data on request.
Have a specification to quote?
Send substrate, dimensions, optical spec, and quantity — we will return feasibility, a coating curve, and prototype pricing. sales@gobofactory.com / WhatsApp +86 13456752363.