Choosing a Standard Filter or Requesting a Custom Design: What to Send KUPO

You have found a KUPO filter that looks close, but its curve is not quite what you need. Should you try it, ask for a different size, or request a new spectral design?

Start by telling us what is already a good match and what needs to change. A product code gives us a shared starting point. Your application tells us whether that starting point is useful.

When an existing design is a useful starting point

Look for a curve that overlaps your useful wavelengths, reduces the unwanted regions and has relevant measurement coverage. Then check the physical and operating requirements.

A listed design or sample-book entry does not by itself confirm stock availability, a particular mount, or performance at a different angle. Ask about those details before planning around the part.

If the spectrum is suitable but the size differs, say so. If the dimensions fit but an edge must move, describe the wavelength change. Those are different design questions.

Send these details if you have them

• The job: what the system does and what optical problem you want to solve.
• The useful light: wavelengths to pass or reflect, with transmission or reflection targets if known.
• The unwanted light: wavelengths to reduce and the required blocking, if defined.
• The geometry: working angle, beam shape and filter position.
• The part: size, thickness, clear aperture, substrate or drawing.
• The environment: temperature, optical power and relevant exposure or durability conditions.
• The project: evaluation quantity, expected production quantity and target timing.

Mark unknowns as unknown. It is better to explain the application than to guess a demanding optical number that may not address the problem.

An example of a useful first inquiry

“We are using an 850 nm LED and a monochrome camera to inspect printed packaging. Sunlight through a nearby window changes the image. We have attached the LED spectrum and camera model. The filter will sit in front of the lens; the clear aperture needs to be 20 mm. We would like to evaluate five samples before choosing a production design. We have not yet defined the blocking requirement.”

This is an illustrative inquiry, not a specification or a product recommendation. It gives us enough context to ask useful follow-up questions without pretending that all requirements are already settled.

A sample curve and an order specification serve different purposes

A measured sample shows how that sample behaved under its measurement conditions. It helps you evaluate a starting design. An order specification defines what must be delivered and accepted.

Before proceeding, agree the relevant spectral limits, dimensions, tolerances and measurement conditions. If you need test documentation or a particular acceptance method, include that request explicitly. Do not assume that every displayed curve establishes a production tolerance.

Make your evaluation representative

Test with the intended source, detector, angle and operating settings. Include the variation that matters in service, such as different materials or changing background illumination. Record what improved and what remains unresolved.

Those observations are often more useful than simply reporting that a filter “looks good.” They help connect the component specification to the result you need.

Start an inquiry with KUPO Optics. For drawings or spectra, email dichroic@kupo.com.tw and include the product code or project name. You can begin with a question and develop the specification with us.