Accessories for Machine Vision Products - STEMMER IMAGING


Important enablers for the perfect solution

Midwest optical filters

Filters for industrial imaging applications

MidOpt filters are specifically made for industrial imaging applications and designed to offer high transmission, block unwanted light and improve overall image quality.

Every filter is produced with the highest standards in durability, so they can withstand even the harshest environments. Unlike traditional filters, MidOpt filters are designed with a Gaussian transmission curve to allow maximum transmission, emulate the output of the most common LED wavelengths and are less angular dependent.


Bandpass filters (BP series)

The bandpass filters from MidOpt are available in UV, Vis and NIR passbands and achieves optimal contrast. They improve the system control, repeatability and stability. By blocking interfering wavelength, MidOpt bandpass filters eliminates the need for shrouds. They also provide an increased resolution by reducing the chromatic aberration. The anti-reflection coating offers maximum transmission. In addition to the standard sizes and shapes, custom filters are also possible.

Bandpass filters can be used in a variety of industries, including machine vision, factory automation, security and surveillance, license plate recognition, medical and life science, agricultural inspection, aerial imaging, motion analysis, photography and cinematography.

BP Series – Broad Bandwidth The BP Series is designed with a broad, Gaussian passband to mimic and accommodate the entire output of the most common LED wavelengths. The glass is double side polished for exceptional parallelism and optical flatness.

The StablEdge® design reduces the angular dependency and minimizes short-shifting effects. BP Series are the most popular filters used in machine vision and factory automation systems and are a critical element in fluorescence imaging.

Longpass filters (LP series)

Longpass filters are designed to pass a broad spectrum of longer wavelengths while blocking shorter wavelengths. They can also be combined with shortpass filters to create a custom Bandpass filter. The glass is polished on both sides for exceptional parallelism and optical flatness and also has an anti-reflection coating for maximum transmission in VIS and NIR spectrums. The StablEdge® design reduces the angular dependency and minimises short-shifting effects.

The LP Series is split into the standard LP series with different transmission curves and the lens protection series which includes different models with and without Anti reflection coating, UV absorbing, UV blocking filter and a protection window for high transmission and heat resistance.

Multi-bandpass filters (DB and TB series)

These dual and triple bandpass filters passes are designed for visible light and a specific range of the visible (VIS) and near infrared (NIR) spectrums. That makes them ideal for colour camera applications that utilise sunlight during the day and NIR illumination at night. By blocking interfering wavelengths they achieve an accurate colour rendition and eliminate the need for dual sensor imaging. The Anti-reflection coating offers maximum transmission.

Dual and triple bandpass filters can be used in variety of applications. They are becoming more popular in NDVI aerial drone inspection, allowing for single sensor imaging and reduced operation payload.

Shortpass / NIR cut filters

Shortpass filters are designed to have a sharp transition between shorter wavelengths (which are transmitted) and longer wavelengths (which are blocked). They can also be combined with longpass filters to create a custom bandpass filter. The anti-reflection coating offers maximum transmission.

SP Series – VIS pass These filters separate colours in monochrome or colour applications and they also improve the contrast and resolution.

SP Series – VIS pass/near-IR block These filters are commonly placed over the camera´s image sensor to block NIR light and achieve natural colour rendition. They are also used as a hot mirror to reduce unwanted heat build-up caused by IR radiation.

Protective filters

The AC and LP series are designed to shield the lens and lighting from dirt, dust, liquids, impact and harsh environments without sacrificing image quality. They are available in glass and acrylic with a high-efficiency, anti-reflection coating to maximise transmission to 98% or more. These filters are useful for imaging in ultraviolet, visible and near-infrared spectra. The protective filters are an economical way of protecting expensive lenses. The AC series is an acrylic longpass protection filter while the LP series is made of glass.

Neutral density filters (ND + Ni series)

Neutral density filters work like “sunglasses” for your system and can be used with monochrome or colour cameras. Designed to reduce light intensity neutrally over a specific wavelength range without affecting image colour or contrast, these filters can be stacked with each other to test various optical densities. These filters are available in a variety of optical densities, they can help to minimise the pixel saturation and reduce the light intensity while maintaining a wide aperture and a shallow depth of field.

ND series- Visible Spectrum This filter series is an absorptive series which is effective from 425 - 675 nm and is available in optical density ranges from 0.10 - 6.0

NI series- Broad Spectrum; VIS/NIR This neutral density filter series is available in optical density ranges from 0.3 - 1.2 with low reflectivity from 400 - 1100 nm. They are coated on low-expansion, heat-resistant Borofloat® glass.

Polarising filters

Polarising filters are designed to reduce specular glare by only transmitting light polarised in the direction perpendicular to the reflected light (glare). In addition, they help to improve contrast, increase colour saturation and detect imperfections in transparent materials. The polarising filters can easily be mounted in front of lenses and light sources for maximum glare reduction.

Polarising sheets These can be placed over a light source and are available in high-temperature-resistant laminate and glass. The linear polarisers are available for visible and near-infrared, while the left and right circular polarisers are only available in the visible spectrum. The contrast ratio average is up to 10.000:1. The PSA007 and HTA008 are both self-adhesive.  

Polarising filters The linear, circular and wire grid polarizers are available for visible and near-infrared spectra. They are available with standard rotating mount and locking thumb screw to fine tune glare reduction. Contrast ratio average is up to 10.000:1

Light balancing filters (LA, LB and FL series)

Light balancing filters correct artificial lighting so colours appear more natural, preventing the need for additional software processing. This allows for greater image stability and control. The filters also increase contrast by correcting the emission spectrum of various light sources. They have an exceptional surface quality, with a 40/20 scratch/dig.

LA series: This filter reduces blue shading is commonly used with white LEDs and xenon strobe lights

LB series: This filter suppresses the reddish hue found with some tungsten, halogen, sodium and other light similar sources

FL series: This filter is used to reduce the greenish cast created by fluorescent lighting.

Acrylic filters

Acrylic longpass filters and the acrylic bandpass filters are a durable, lightweight, and economical solution for inspection windows. They can protect a lens in environments where broken glass might pose a problem.

These acrylic filters have a high transmission ranging from 90 to 98%. They are impact-resistant and available with an anti-reflection coating for maximum transmission. The optical-grade Acrylic filters are also half of the weight of glass filters.


  • For lenses, which have no filter threads and a lens outer diameter between, slip mounted filters are available, sizes range from 13.2mm to 101mm.
  • Unmounted filters can be ordered in round, square and rectangular shapes. Sizes can range from 10mm to 105mm (diameter or side length).
  • Some filters are only available in limited sizes, please contact our sales team to discuss your requirements.