Get inspired by the products we have already made - or let us design your custom Bandpass Filter
Optical Bandpass Filters
Optical Bandpass Filters are spectrally selective components capable of transmitting specific wavelengths of light while blocking others. These filters are fully customizable in terms of center wavelengths and bandwidths, making them suitable for a wide range of applications, including fluorescence spectroscopy, microscopy, and flow cytometry. Optical Bandpass Filters provide consistent optical filter functions across the entire clear aperture. In contrast, Continuously Variable Filters offer a filter function that varies along one dimension of the filter.
Delta Optical Thin Film are pioneers and innovators in the design and manufacture of robust optical thin film components for a broad range of volume applications. We have designed and manufactured optical interference bandpass filters since the early 1970’ties.
Most of our products are custom designed filters and the examples we show on this webpage are just for inspiration. We often find benefits for our customers in a custom designed solution. Delta Optical Thin Film is focusing mainly on optical bandpass filters with passbands in the range from 300 nm to 1200 nm.
Choose from a large range of existing bandpass filters
Narrow bandpass, Broad bandpass, Laserline, TopPride™ – or get your own custom design made
Delta Optical Thin Film manufactures Bandpass Filters using either Plasma Assisted Evaporation Technology or Magnetron Sputtering Technology, depending on our customers’ requirements. On this web site you can find examples of optical Bandpass Filters we have already designed and manufactured.
The data sheets show actual measurements (not design curves) with typical transmission curves for unpolarized light and an AOI=0°.
As we often can optimise design and manufacturing methods to the individual application, please get in touch to discuss how we can best help facilitating your application.
If you cannot find the Bandpass Filter you need among our standard products, please do not hesitate to contact us to discuss your requirements. When specifying your filter, our technical note on specifying optical filters will help you avoid the main cost drivers in filter design.
Product specifications
| λcenter (nm) | FWHM (nm) | Tpeak (%) | Product number | Max size | Data sheet |
|---|---|---|---|---|---|
| 377 | 28 | 80 | LF101840 | Round diameter 25 mm x 2 mm |  |
| 436 | 10 | 50 | LF101532 | Round diameter 25 mm x 2 mm | |
| 464 | 60 | 93 | LF104547 | Round diameter 25 mm x 2 mm | |
| 470 | 35 | 80 | LF101830 | Round diameter 25 mm x 2 mm | |
| 470 | 40 | 75 | LF101607 | Round diameter 25 mm x 2 mm | |
| 470 | 40 | 65 | LF101881 | Round diameter 25 mm x 2 mm | |
| 470 | 40 | 89 | LF101785 | Round diameter 25 mm x 2 mm | |
| 470 | 40 | 93 | LF104539 | 80 mm x 55 mm x 1 mm | |
| 475 | 30 | 92 | LF101157 | Round diameter 25 mm x 2 mm | |
| 475 | 40 | 75 | LF102060 | Round diameter 25 mm x 2 mm | |
| 480 | 40 | 75 | LF101533 | Round diameter 25 mm x 2 mm | |
| 480 | 220 | 93 | LF104551 | 80 mm x 55 mm x 1 mm | |
| 482 | 35 | 90 | LF104924 | 80 mm x 55 mm x 1 mm | |
| 505 | 16 | 93 | LF104540 | 80 mm x 55 mm x 1 mm | |
| 525 | 50 | 75 | LF102018 | Round diameter 25 mm x 2 mm | |
| 525 | 50 | 92 | LF101787 | Round diameter 25 mm x 2 mm | |
| 526 | 14 | 93 | LF104541 | 80 mm x 55 mm x 1 mm | |
| 530 | 50 | 80 | LF102062 | Round diameter 25 mm x 2 mm | |
| 534 | 51 | 90 | LF104931 | 80 mm x 55 mm x 1 mm | |
| 535 | 45 | 80 | LF101969 | Round diameter 25 mm x 2 mm | |
| 535 | 50 | 75 | LF101752 | Round diameter 25 mm x 2 mm | |
| 540 | 50 | 85 | LF101535 | Round diameter 25 mm x 2 mm | |
| 545 | 25 | 75 | LF101885 | Round diameter 25 mm x 2 mm | |
| 546 | 12 | 70 | LF101592 | Round diameter 25 mm x 2 mm | |
| 546 | 12 | 92 | LF103015 | Round diameter 25 mm x 2 mm | |
| 550 | 190 | 90 | LF103000 | Round diameter 25 mm x 2 mm | |
| 558 | 14 | 93 | LF104548 | 80 mm x 55 mm x 1 mm | |
| 558 | 55 | 80 | LF100924 | Round diameter 25 mm x 2 mm | |
| 558 | 295 | 94 | LF104552 | 80 mm x 55 mm x 1 mm | |
| 560 | 40 | 75 | LF101537 | Round diameter 25 mm x 2 mm | |
| 572 | 25 | 92 | LF101708 | Round diameter 25 mm x 2 mm | |
| 579 | 16 | 93 | LF104542 | 80 mm x 55 mm x 1 mm | |
| 587 | 25 | 92 | LF101757 | Round diameter 25 mm x 2 mm | |
| 592 | 24 | 80 | LF101712 | Round diameter 25 mm x 2 mm | |
| 605 | 70 | 85 | LF102020 | Round diameter 25 mm x 2 mm | |
| 607 | 80 | 92 | LF101706 | Round diameter 25 mm x 2 mm | |
| 608 | 65 | 85 | LF101599 | Round diameter 25 mm x 2 mm | |
| 612 | 12 | 93 | LF104545 | 80 mm x 55 mm x 1 mm | |
| 630 | 60 | 92 | LF101710 | Round diameter 25 mm x 2 mm | |
| 632 | 12 | 93 | LF104543 | 80 mm x 55 mm x 1 mm | |
| 640 | 30 | 80 | LF101659 | Round diameter 25 mm x 2 mm | |
| 647 | 70 | 92 | LF101758 | Round diameter 25 mm x 2 mm | |
| 661 | 12 | 93 | LF104544 | 80 mm x 55 mm x 1 mm | |
| 670 | 360 | 95 | LF104553 | 80 mm x 55 mm x 1 mm | |
| 681 | 16 | 93 | LF104546 | 80 mm x 55 mm x 1 mm | |
| 690 | 50 | 80 | LF101658 | Round diameter 25 mm x 2 mm | |
| 707 | 16 | 80 | LF101727 | Round diameter 25 mm x 2 mm | |
| 731 | 40 | 93 | LF104549 | 80 mm x 55 mm x 1 mm | |
| 770 | 40 | 80 | LF101729 | Round diameter 25 mm x 2 mm | |
| 827 | 425 | 95 | LF104554 | 80 mm x 55 mm x 1 mm | |
Defining Optical Bandpass Filters
The function of a Bandpass Filter (BP filter) is described by the center wavelength of its transmission band and the with of the band. E.g. a Bandpass Filter can be described as BP578/50, which is a filter with a center wavelength of 578 nm and a bandwith of 50 nm. Within the passband, it is typical to define the minimal or average transmission level. In modern coatings, despite several hundreds of layers, minimum transmission levels of 90% is not uncommon.
Another important aspect of a Bandpass Filter is the rejection or blocking range and level. These parameters specify in which wavelength ranges the filter must reflect as well as the permitted transmittance at these wavelengths.
Modern filters often provide OD6 or better rejection in a very wide wavelength range. However, overspecifying blocking level and range will often lead to an increase in the number of layers in the filter causing increased production cost.
Also, deep blocking is cumbersome and slow to verify in a photo spectrometer. At Delta Optical Thin Film, we always enter into a thorough discussion with our customers to prevent unnecessary cost.
What is the difference between a narrow bandpass and a broad bandpass filter?
A narrow bandpass filter transmits only a very small range of wavelengths — typically a Full Width at Half Maximum (FWHM) of less than 10–20 nm — making it ideal for isolating specific spectral lines, such as those from lasers or fluorescent dyes. A broad bandpass filter passes a wider band of wavelengths and is suited for applications where a larger portion of the spectrum is needed, such as general fluorescence imaging or colour separation. The right choice depends on how selectively you need to isolate your target wavelength from neighbouring signals.
Can I order a filter with a centre wavelength or bandwidth not listed in your product table?
Yes — the vast majority of filters Delta Optical Thin Film delivers are custom-designed. The products shown on the website are examples for inspiration only. If your application requires a specific centre wavelength, bandwidth, transmission level, or physical size not found in the standard range, please contact us to discuss your requirements. We manufacture custom filters using either Plasma Assisted Evaporation Technology or Magnetron Sputtering Technology, depending on the specifications needed.
What do the specifications λcenter, FWHM, and Tpeak mean in the product table?
λcenter is the centre wavelength of the filter's transmission band, expressed in nanometres (nm). FWHM (Full Width at Half Maximum) describes the bandwidth — that is, the range of wavelengths transmitted at 50% or more of the peak transmission level. Tpeak is the maximum transmission achieved within the passband, expressed as a percentage. Together, these three values define the core optical performance of a bandpass filter. All data sheets on this site show actual measurements, not theoretical design curves.
What is TopPride™, and when should I choose it over a standard filter?
TopPride™ is Delta Optical Thin Film's designation for a high-performance filter variant that achieves an exceptionally flat and high transmission profile across the passband — often exceeding 90% peak transmission with very steep edges. It is the preferred choice when your application demands maximum signal throughput, minimal spectral distortion, or particularly sharp cut-on and cut-off slopes. Applications such as high-sensitivity fluorescence microscopy or flow cytometry typically benefit most from TopPride™ performance.
What factors drive up the cost of a custom bandpass filter?
The main cost drivers are over-specification of blocking level and blocking range. Demanding very deep blocking — such as OD6 or better — across a wide wavelength range requires a significantly higher number of coating layers, which increases both production time and complexity. Deep blocking levels are also slow and demanding to verify on a spectrophotometer, adding to overall cost. At Delta Optical Thin Film, we always engage in a thorough discussion with customers before finalising specifications, to ensure the filter is optimised for the actual application without unnecessary cost.
Get in touch
Have a look at our existing products or get in touch regarding your needs – we are the optical filter company.