Where Image Quality Begins

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Harold Leonard
5 years ago
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1 Where Image Quality Begins

2 Filters are a Necessity Not an Accessory

3 Inexpensive Insurance Policy for the System The most cost effective way to improve repeatability and stability in any machine vision system Achieve consistent results with Machine Vision Filters Simplest & quickest way to protect the system Save Money & Space Optical filters can eliminate light shields

4 Pass Light = Highlight Color How filters increase contrast Selectively pass or block light wavelengths which can highlight or darken areas of an image Block Light = Darken Color Pass Light with Green Bandpass Filter and Highlight Green Colored Marker Blocked Wavelengths with Green Bandpass Filter Darken Blocked Colors

5 White Light Increase Resolution Before Bandpass Filter After Bandpass Filter NIR NIR VIS VIS UV UV A type of distortion in which the lens does not focus all colors to the same convergence point

6 Extreme durability

7 Does the quality of the filter matter? Filters designed for photographic film are not suitable for digital imaging systems! Color Image, No Filter Photographic Film Relative Spectral Response CCD/CMOS Red Photographic Filter Lightens (passes) red wavelength Relative Spectral Response: Black and White Film vs Digital CCD/CMOS Sensor Green Photographic Filter Darkens (blocks) red wavelength

8 Machine Vision Bandpass Filters

9 Bandpass Filters Developed for Machine Vision A/R Coated for Highest Possible Peak Transmission Improve LED & Overall System Performance Less Susceptible to AOI shifting Precision Optical Quality Surface Quality: 40/20

10 Reduced Angular Dependence MidOpt BP635 Light Red Bandpass Filter MidOpt Bandpass Filters are Less Sensitive to Wider Angles of Incidence Traditional Interference Filter Dichroic (reflective) type coatings are angle sensitive & will shift to shorter wavelengths at higher degree angles

11 BN & Bi Series Filters Choosing the Right Filter MidOpt BN630 Narrow Light Red Bandpass Reduced angular dependence Best choice with short focal length lenses Red laser diode with 6mm FL lens Bi632 BN630 MidOpt Bi632 Light Red Interference Bandpass Filters Higher transmission at 0 Absolute separation of subject matter Often used in the biomedical industry

12 Test the Effects of Monochromatic Illumination Blue LED highlights push pin White LED no filter, no contrast Blue Bandpass Filter highlights blue push pin

13 Test to Determine Your Optimal LED wavelength Utilize a broad spectrum light source with Bandpass Filters to test & determine the optimal LED wavelength for your application

14 Color Sorting Results MidOpt BP660 Red Bandpass Filter MidOpt BP470 Blue Bandpass Filter Original color image No Filter

15 Monochromatic imaging with optical filters significantly increases camera efficiency Color Monochrome Monochrome with Filter MidOpt Blue Bandpass Filter 25% Efficient 90% Efficient Each pixel in a monochrome sensor is used to detect intensity. Combined with a blue bandpass filter that transmits 90+%, a monochrome sensor vs a color sensor is at least 3 times more efficient Original Color Image, UV 395nm LED Blue fluorescence; No Filter Blue Bandpass Filter

16 UV Fluorescence Imaging Excitation light source interferes with weaker emitted fluorescence without the use of filters No Filter, 395nm UV Light 395nm UV Light with MidOpt BP470 Blue Bandpass Filter

17 Convert your Camera into an Infrared Imager View the invisible with IR Bandpass filters Before Filter After Filter

18 Other Filters Used in Vision Applications

Contrast Polarizing Filters & Polarizing Film PR032 Linear

1000 Before Filter After PR032 Linear Polarizer 0 400 450 500

glare by using a polarizer over the lens and a polarizer film

polarizer must be used Lens polarizer with locking thumb screw

19 Contrast Polarizing Filters & Polarizing Film PR032 Linear Polarizer 7000 Useful Range: nm Before Filter After PR032 Linear Polarizer Wavelength (nm) (Typical) Minimize specular glare by using a polarizer over the lens and a polarizer film over the light source For imaging above 700 nm Infrared polarizer must be used Lens polarizer with locking thumb screw to prevent change of orientation Custom sheet shapes & sizes to fit the light source

Polarizing Filters Can Improve Image Quality by

Significant glare remains Minimal glare from

20 Polarizing Filters Can Improve Image Quality by Reducing Glare No Filter Polarizing Filter Polarizing Filter & Film BP660 + Polarizing Filter & Film Glare from LED & ambient light Significant glare remains Minimal glare from ambient light remains Further reduces glare & improves contrast

21 Neutral Density Filters Before Filter After Filter Before Filter After Filter

22 Shortpass / Near-IR Cut Filters Before Filter After Filter Lets shorter wavelengths pass while blocking the longer ones Block IR light from interfering with color rendition in CCD/CMOS cameras Commonly placed over the image sensor

Useful in blocking excitation light source while

an issue Longpass filters can be used to pass

590 & 850 nm A/R coating increases transmission

23 Longpass Filters (High Pass, Sharp Cut) Economical solution when shrouding is present Useful in blocking excitation light source while passing all emission where ambient light is not an issue Longpass filters can be used to pass multiple LEDs Ex. 590 & 850 nm A/R coating increases transmission For traffic & security applications, the acrylic Infrared Longpass is ideal Before Filter After Filter

24 Dual (Visible + Infrared) Bandpass Filters Use for color camera day/night applications along with IR illumination Blocks interfering IR wavelength range to achieve accurate color rendition Ability to view with IR illumination at night

solution and useful for FDA requirements & outdoor applications Materials: High efficiency anti-reflection

25 Protective / UV Blocking Filters Protect lenses from dust and harsh industrial environments Anti-reflection coatings maximize transmission Hard coated acrylic protective windows are an economical solution and useful for FDA requirements & outdoor applications Materials: High efficiency anti-reflection coatings standard on AC380, LP285, LP340 & LP415 Acrylic or glass options; anti-reflection coated or uncoated alternatives

Light Balancing Filters The best image quality is achieved through optics, not software processing. Before Filter No Filter, Cool White LED s can affect image quality in a color application.

26 Light Balancing Filters The best image quality is achieved through optics, not software processing. Before Filter No Filter, Cool White LED s can affect image quality in a color application. After Filter After MidOpt LA120 Color Balancing Filter, Image appears more natural allowing easy detection of adhesive and color sorting. Cool White LED, with MidOpt LA120 Mimics output of warm LED Lower cost than a warm LED Avoid software color correction

27 Evaluate & Improve Image Quality with MidOpt Filter Test Kits

28 Machine Vision Filter Test Kits

29 Mounting Solutions & Accessories

30 Mounts for Any System Solutions for any lens with or without filter threads; C/CS camera mounts & custom shaped filter glass Threaded Mount Slip-On Mount C/CS Mount Unmounted

31 Choosing the proper mount for wide angle lenses Filter in front of lens Image Result C-Mount Filter behind lens Image Result

32 Lens Accessories CS Mount Lens Enclosure Step Rings Lens Extension Tubes Right Angle Attachment

33 Custom optical components for industrial vision & lighting Precision Optical Windows Focusing Lenses Light Pipes Polarizers Prisms Dust Covers Diffusers Mirrors Filters Beamsplitters Wedges

34 MidOpt Optical Filters are the simplest, quickest and most cost effective way to improve repeatability and stability in any machine vision system. Thank You

Choosing the Best Optical Filter for Your Application. Georgy Das Midwest Optical Systems, Inc.

Choosing the Best Optical Filter for Your Application Georgy Das Midwest Optical Systems, Inc. Filters are a Necessity, Not an Accessory. Key Terms Transmission (%) 100 90 80 70 60 50 40 30 20 10 OUT-OF-BAND