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| Midopt Filters Back to Manufacturers |
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| • Machine vision | • License-plate
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About MidOpt and their products |
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| The MidOpt line of mounted, single substrate,
hard-coated filters are specifically created for industrial
machine vision applications. They: • are very durable • are non-hydroscopic • withstand repeated cleaning with solvents • withstand high heat, humidity, vibration • have an almost-unlimited life For machine vision, the ideal filter should be an immediate solution that provides greater contrast, improved transmission and resolution, and long term control over the variability of ambient light |
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| • | Good contrast enables increased accuracy and speed. Because ambient light is everywhere, filters create the contrast needed to control lighting |
| • | By increasing the contrast, filters improve the ability of the system to distinguish desired characteristics |
| • | Lenses are a critical part of any vision system so they need to be protected from dust and scratches. Filters provide that protection |
Left: Kale leaves under white
light through a monochrome camera. Right: MidOpt Bandpass Filter creates much greater contrast. |
Left: unfiltered monochrome image with ambient
light Right: Correctly aligned polarising filter eliminates the reflections |
Working with filters
Filter selection is made by matching a filter type to the available lighting.
When matched with the correct lighting, optical filtering is one
of the most important factors that contributes to the ability
of any vision system to perform reliably over the intended lifespan. Consequently,
selecting the right filter for the job is critical, not just at the time
it is first put into service but also for the long term. Filters are designed
to work with a wide variety of lighting: monochromatic or white LED, fiber
optic, structured diode-generated patterns and other lighting commonly
used in machine vision applications. Their job is to increase the contrast
of the subject under inspection, improving the ability of the system to
distinguish desired characteristics. Increased contrast allows for increased
accuracy and speed. Because lighting will change over time and ambient
light is everywhere, filters create the contrast needed.
Filter selection is made by matching a filter type to the lighting and
sizing to the diameter of the camera lens and filters should be designed
with the capacity to mount, quickly and securely, to the smaller diameter
lenses used by CCD and CMOS cameras. MidOpt filters are engineered and
sized to each mount for maximum field of view and are ready to use right
out of the box. See filter
mounts.
Additionally, lenses are a critical part of any vision system, so at the
very least, need to be protected from dust and scratches by using a filter.
| Typical results and benefits when using machine vision filters |
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1. |
Colour recognition and separation of subject
matter Lower cost better speed, higher contrast and more consistent reliability can be achieved in some cases by using filters with a monochrome camera as compared to using a color camera alone. |
2. |
Suppress the strong blue "spike"of
standard white LED and metal halide lighting Lower costs, brighter images and longer system lifetimes can be achieved by using the LA120 with standard lighting versus selecting "warm white" LED lighting |
3. |
Improve lens resolution and contrast by reducing
the colour range being imaged Better resolution reduces false accepts and false rejects, and the more expensive "megapixel" lensing may not be needed. See image above, left |
4. |
Eliminate glare When it is not possible to adjust a system's lighting configuration, polarized glare is selectively removed only through the use of a polarizing filter. See image above, right |
5. |
Test the effects of Infrared light...
and see what eyes can’t The very best contrast and separation of subject matter is often achieved by working in the infrared. The odds of this being immediately successful are about 50/50; testing is usually the only way to make such a determination. |
6. |
Enhance contrast for improved viewing of desired
features Fluorescence applications require a filter to block the overwhelming light source that excites the fluorescence. Detecting the much weaker fluorescence is difficult/impossible without blocking the light source and ambient light. A bandpass filter that only passes the limited fluorescence will significantly improve the contrast and allow the weak glow to be detected. |
7. |
Test LED colors without the expense and lead
time of the lighting Quickly test common LED lighting colours without the expense and time wasted while waiting for the appropriate LED lighting. Cut the lead time for bringing a system on-line by as much as several weeks |
8. |
Radiation and temperature IR blocking Certain machine vision filters can be used to block the bright glow of hot metals, glass and other material. Shortpass filters allow light up to a specific wavelength to pass through while blocking all light at higher wavelengths. This useful feature permits, for example, the viewing of hot rolled steel to see certain temperature areas while not blinding the system from the brighter, hotter areas. |
| Narrow Blue Bandpass/UV block 450-495nm | IR Longpass – IR Vidicon/InGaAs cameras | ||
| Narrow Green Bandpass 515-560nm | Yellow Longpass – blocks most blue and UV wavelengths | ||
| Narrow Orange Bandpass 570-615nm | Yellow-Orange Longpass – blocks all blue and UV | ||
| Narrow Light Red Bandpass/UV block 610-650nm | IR Longpass – IR LED's @ 720nm | ||
| Narrow Dark Red Bandpass/UV block 640-680nm | IR Longpass – IR diode lasers @ 810nm | ||
| Narrow IR Bandpass 720-770nm | IR Longpass – general IR +880nm IR LEDs | ||
| Narrow IR Bandpass 760-805nm | IR Dichroic Longpass – IR LEDs @ 940nm | ||
| Narrow IR Bandpass 825-870nm | Optical Density = 0.3 (T = 50%) – reduces light intensity | ||
| Broadband UV Bandpass – deep broadband UV imaging | OD = 0.6 (T = 25%) – reduces light intensity | ||
| UV 'A+B' Bandpass – mid- to near-UV imaging | OD = 0.9 (T = 12.5%) – reduces light intensity | ||
| Blacklite/UV 'A' Bandpass – UV imaging/UV lighting dichroic filter | OD = 1.2 (T = 6.3%) – for viewing into lamps | ||
| Blue Bandpass - blue LEDs/UV fluorescence | Magenta Dichroic Shortpass – blocks green & passes blue & red wavelengths | ||
| Cyan Bandpass – for 505nm LED lighting | Optical Density = 0.3 (50%) – reduces light intensity | ||
| Light Green Bandpass – green LEDs/fluorescence | OD = 0.6 (25%) – reduces light intensity | ||
| NIR-UV Block/Visible Pass – 400-700nm | OD = 0.9 (12.5%) – reduces light intensity | ||
| Orange Bandpass – amber/orange LEDs/UV fluorescence | OD = 1.2 (6.3%) – for viewing into lamps, furnaces, welding processes, etc. | ||
| Light Red Bandpass – high-power red LEDs | Circular Polarizer – reduces glare; for autofocus or autoiris lenses; for visible spectrum | ||
| Dark Red Bandpass – darker red LEDs and structured laser diodes | IR Linear Polarizer – reduces only infrared glare | ||
| IR Bandpass – NIR fluorescence | Rotating Linear Polarizer with locking screw – reduces glare in the visible spectrum | ||
| IR Bandpass – IR LEDs @ 735nm | Blue Dichroic Shortpass – for sorting gold from silver or plated metal parts | ||
| IR Bandpass – best choice if thin filter needed over sensor | Blue-Green Dichroic Shortpass – blocks orange to NIR | ||
| IR Bandpass – high-power IR LEDs @ 850nm | Cyan Dichroic Shortpass – blocks red and very near IR | ||
| IR Bandpass – IR LEDs @ 880nm | Blue-Orange Dichroic Shortpass – blocks deep red/NIR | ||
| Dual Bandpass VIS+850 IR - visible 385-650nm +IR 820-880nm | Mid-Red/NIR Dichrioc Block – best IR/mid-red block | ||
| Dual Bandpass VIS+940 IR- visible 385-650 + 910-970nm | Deep Red/NIR Dichrioc Block – best IR/deep red block | ||
| Minus Green – removes green cast from fluorescent lighting | Hot Mirror/NIR Dichroic Block – standard IR block, for use with monochrome cameras | ||
| Minus Blue + – removes blue cast from white LED and metal halide lighting | Hot Mirror/NIR Colourless Block – standard IR blocking, for use with colour cameras | ||
| Minus Red – removes yellow cast from halogen lighting | |||
| Filters by type | |
| BP470 – Blue Bandpass - blue LEDs/UV
fluorescence |
PR032 – Rotating Linear Polarizer with locking screw – reduces glare in the visible spectrum |
| BP505 – Cyan Bandpass – for 505nm LED lighting | PC052 – Circular Polarizer – reduces glare; for autofocus or autoiris lenses; for visible spectrum apps |
| BP525 – Light Green Bandpass – green LEDs/fluorescence | I035 – IR Linear Polarizer – reduces only infrared glare |
| BP590 – Orange Bandpass – amber/orange LEDs/UV fluorescence | |
| BP635 – Light Red Bandpass – high-power red LEDs | |
| BP660 – Dark Red Bandpass – darker red LEDs and structured laser diodes | |
| COLOUR
NARROW BANDPASS |
NEUTRAL DENSITY - ABSORPTIVE FILTERS |
| BN470 – Narrow Blue Bandpass/UV block 450-495nm | ND030 – Optical Density = 0.3 (T = 50%) – reduces light intensity |
| BN532 – Narrow Green Bandpass 515-560nm | ND060 – OD = 0.6 (T = 25%) – reduces light intensity |
| BN595 – Narrow Orange Bandpass 570-615nm | ND090 – OD = 0.9 (T = 12.5%) – reduces light intensity |
| BN630 – Narrow Light Red Bandpass/UV block 610-650nm | ND120 – OD = 1.2 (T = 6.3%) – for viewing into lamps |
| BN660 – Narrow Dark Red Bandpass/UV block 640-680nm | |
| INFRARED
NARROW BANDPASS |
NEUTRAL DENSITY - LOW-REFLECTIVITY FILTERS |
| BN740 – Narrow IR Bandpass 720-770nm | NI030 – Optical Density = 0.3 (50%) – reduces light intensity |
| BN785 – Narrow IR Bandpass 760-805nm | NI060 – OD = 0.6 (25%) – reduces light intensity |
| BN850 – Narrow IR Bandpass 825-870nm | NI090 – OD = 0.9 (12.5%) – reduces light intensity |
| NI120 – OD = 1.2 (6.3%) – for viewing into lamps, furnaces, welding processes, etc. | |
| DUAL
BANDPASS |
UV BANDPASS |
| DB850 – Dual Bandpass VIS+850 IR - visible 385-650nm +IR 820-880nm | BP250 – Broadband UV Bandpass – deep broadband UV imaging |
| DB940 – Dual Bandpass VIS+940 IR- visible 385-650 + 910-970nm | BP324 – UV 'A+B' Bandpass – mid- to near-UV imaging |
| BP365 – Blacklite/UV 'A' Bandpass – UV imaging/UV lighting dichroic filter | |
| INFRARED
PASS - VISIBLE BLOCK |
SHORTPASS/NOTCH COLOUR |
| LP695 – IR Longpass – IR LED's @ 720nm | SP510 – Blue Dichroic Shortpass – for sorting gold from silver or plated metal parts |
| LP780 – IR Longpass – IR diode lasers @ 810nm | SP570 – Blue-Green Dichroic Shortpass – blocks orange to NIR |
| LP830 – IR Longpass – general IR +880nm IR LEDs | SP585 – Cyan Dichroic Shortpass – blocks red and very near IR |
| LP920 – IR Dichroic Longpass – IR LEDs @ 940nm | SP625 – Blue-Orange Dichroic Shortpass – blocks deep red/NIR |
| LP1000 – IR Longpass – IR Vidicon/InGaAs cameras | NF550 – Magenta Dichroic Shortpass – blocks green & passes blue & red wavelengths |
| BP695 – IR Bandpass – NIR fluorescence BP850 – IR Bandpass – high-power IR LEDs @ 850nm | |
| BP735 – IR Bandpass – IR LEDs @ 735nm | |
| BP800 – IR Bandpass – best choice if thin filter needed over sensor | |
| BP850 – IR Bandpass – high-power IR LEDs @ 850nm | |
| BP880 – IR Bandpass – IR LEDs @ 880nm | |
| INFRARED
BLOCK - VISIBLE PASS |
LONGPASS COLOUR |
| BP550 – NIR-UV Block/Visible Pass – 400-700nm | LP500 – Yellow Longpass – blocks most blue and UV wavelengths |
| SP645 – Mid-Red/NIR Dichrioc Block – best IR/mid-red block | LP515 – Yellow-Orange Longpass – blocks all blue and UV |
| SP675 – Deep Red/NIR Dichrioc Block – best IR/deep red block | |
| SP700 – Hot Mirror/NIR Dichroic Block – standard IR block, for use with monochrome cameras | |
| SP730 – Hot Mirror/NIR Colourless Block – standard IR blocking, for use with colour cameras | |
| WHITE
LIGHT BALANCING |
ACRYLIC LONGPASS |
| LA120 – Minus Blue + – removes blue cast from white LED and metal halide lighting | AC380 A/R Acrylic Protective Window – abrasion, scratch, breakage- and solvent-resistant acrylic |
| LB080 – Minus Red – removes yellow cast from halogen lighting | AC685 Acrylic NIR Longpass – allows through mainly IR light |
| FL550 – Minus Green – removes green cast from fluorescent lighting | AC760 Acrylic NIR Longpass – allows through mainly IR light and also blocks very near IR |
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