SyronOptics

Shortpass Filter (SPF)

Shortpass filter transmit shorter wavelength and pass through longer wavelength.

  • More than 40 types of Shortpass Filter in Stock
  • Cutoff Wavelength from 360 ~ 1650nm available
  • Standard mount of dia12.5mm and dia25.4mm
  • Custom Cut available for different size of Filters

Quick Guide

for Shortpass Filter

Cut-off Wavelength

In shortpass filter, filter will pass through the light below cutoff wavelength.

  • The wavelength start to transmit could vary based on design ,please go inside product page for details.

For example

  • SP830 transmit from 450nm to 830nm
  • SP360 transmit from 320nm to 360nm

Blocking Region

Blocking region is the wavelength range where the light be blocked (attenuated)

  • You may notice some blocking region written as 200-800nm, which may overlap with the transmit area.
  • This is a written convention, transmit region should be excluded.

For example in SP360:

  • T>90%@320-360nm // OD5@200-800nm

The actual blocking region is

  • 200nm-310nm + 370-800nm

Unmentioned Region

Unmentioned are region without spectral performance guarantee.

In unmentioned area curve could be

  • Gradually Decline
  • Frequent Ripple
  • Random Noise

Generally, do not considering using the unmentioned area as a part of your design.

For example in SP1310:

  • T>90%@750-1300nm // OD5@1350-2070nm

Unmentioned Region:

  • 200-750nm

Transition Region

The area transmission go from bottom to top or vice versa.

Left side of the Blocking Band
-
Right side of the Pass Band
=
Transition Region

For example in SP1310:

  • T>90%@750-1300nm // OD5@1350-2070nm

The transition region is

  • 1350nm-1300nm=50nm

It means : The shortpass filter need 50nm to get from 0% to 90% transmission

  • Shorter Transition Area = Better Shortpass Filter

Cut-off < 400nm

These are UV-pass Shrotpass Filter. Generally they have a limited passband and blocking region due to manufacturing difficulties.

Cut-off < 700nm

These are UV-VIS pass shortpass filter. The blocking region usually extend to around 1000 ~ 1200nm.

Most commonly used series.

Cut-off < 1000nm

These are VIS-NIR pass shortpass filter. The blocking region stop at 1000-1400nm.

Cut-off < 2000nm

These are VIS-SWIR pass shortpass filter. The blocking region stop at 1400-2500nm.

Shortpass Filter FAQs

Where does the blocked light goes?

They got reflected.

Shortpass Filter in this page are dielectric coating filters.

The blocked light are reflected, Not absorbed.
Can I use these Shortpass Filter at 45°?

In most of the case, it is not a good idea.

These filters are designed to be used at normal incidence. For AOI within 0-5°, wavelength shift is not significant.

For AOI=45°, you may spot a very sereve wavelength shift and degrade in spectral performance.

However, if you do really want to use shortpass fitler with a variable AOI, we will suggest to use colored glass type Shortpass filter, which is not sensitive to AOI changes.
What's the maximum size of shortpass filter?

Maximum Size Format is 60x60mm

Usually we stocked shortpass at a size of 60x60mm. Upon order we will cut them into smaller sizes.
Is there any shortpass filter transmit below 300nm?

Yes they do exist, but unfortunately we do not make these filters.
Is there a difference for s- and p-polarization transmission ?

No. There's no difference with AOI = 0°

Polarization splitting only occurs as the angle of incidence increases.
What are the factors driving up the price?

Pass Band Region, Blocking Region, Optical Density, Sharp Transition, Surface Quality
Can i combine this with other filters?

Yes definitely, a common case is use a Shortpass Filter + Longpass Filter to form a Customized Bandpass Filter.

Need help finding a Shortpass Filter?

Share your cut-off wavelength, blocking range, transmission range, size, and application. We can help match your requirement to a stocked or custom shortpass filter.