Optical Filter Coatings

  • Wavelength range from 193nm to 12.4µm
  • 960 Standard Filter Coating Design
  • Offers custom design, fabrication and testing
  • Laser line designs that can be used in ultrafast and other laser systems
  • Filters for medical devices, semiconductor inspection, machine vision, and more


Apexel Optics mainly provides filters for colored glass filter applications, fluorescence, dichroic, narrow bandpass, multi-bandpass, notch, edge, and neutral density filters.Whether you need to clean up a laser beam, increase contrast in machine vision, or separate fluorescence from emission wavelengths, Apexel Optics has the right filter solution.
Our advanced coating equipment and techniques offer many advantages over conventional filters in isolating discrete spectra.Our experience in a variety of applications will help you find the best filter for your application. What can we do for you?


Our expert coating designers and technicians are skilled in manipulating coating parameters to meet demanding specification requirements.

* Typical Specifications

TypeCutoff filter, Bandpass filter, Negative filter, Neutral filter,Filters for Fluorescence / Life Science Applications,Machine Vision Filters
MaterialsRegular glass, colored flakes, quartz, sapphire
Maximum Size200mm
Minimum bandwidth5nm
Wavelength positioning accuracy±1% center wavelength
Passband transmittance95%
Cutoff Depth> OD6
Transition band steepness2% of center wavelength
IRR ( @632.8nm)<λ/4 (General), <λ/10 (High Precision)

Manufacturing Equipment

Apexel Optics has state-of-the-art optical coating facilities including,

  • E-Beam Deposition
  • Ion-Assisted Deposition
  • Ion Beam Sputtering
  • Magnetron Sputtering
  • Thermal Evaporation
  • Hard Coatings for Stringent Environments and Durability
  • Automated Ultrasonic Cleaning


Apexel Optics performs a range of testing to ensure the highest performance from our stock and custom optical coatings. Coating metrology equipment:

  • PerkinElmer LAMBDA Spectrophotometers
  • Agilent Cary Spectrophotometers
  • Hitachi Spectrophotometers
  • Varian Spectrophotometers
  • PerkinElmer FTIR Spectrophotometers
  • DIC Microscopes

Types of Filters

Neutral density filters

Neutral density filters attenuate, split or combine beams within a certain range of illuminance ratios with little effect on wavelength. Apexel offers two types of neutral density filters: neutral gray glass, and metal-coated filters made of optical glass such as N-BK7, H-K9L fused silica. The thickness of the neutral gray glass type filter determines the transmittance, however, the transmittance is determined by the coating thickness in the optical material type of metal coating.
Attributes Specification parameters
Neutral Density Glass Type Metallic Coating
Material Optical Neutral Density Glass,N-BK7, Fused Silica
Regular size (mm) Ф25.0 x 2.0, 50.0 x 50.0 x 2.0
Dimensional tolerance (mm) ±0.2
Parallelism 3 arc min.
Flatness (per 25mm@633nm) 2λ (General), λ/2(High Precision)
Surface Quality 80/50 (General), 20/10 (High Precision)
Optical Density 0.04, 0.1, 0.2, 0.3, 0.4, 0.5, 0.8, 1.0, 2.0, 3.0, 4.0, etc. 0.1, 0.2, 0.3, 0.5, 0.8, 1.0, 2.0, 3.0, 4.0, etc.
Optical Density Tolerance ±5%
  Something else:
  • Regular diameters are 10.0mm, 15.0mm, 20.0mm, 25.4mm, and other shapes such as square, triangle or other polygons can also be customized according to customer requirements.
  • The normal dimensional tolerance is ±0.2mm, and higher precision can be achieved if required.
  • The normal parallelism is 3 arc minutes, better parallelism can be achieved if required.
  • The normal flatness is 2λ, and higher accuracy can be achieved if required, such as λ/2.
  • The regular surface quality is 80/50, and higher precision can be achieved if required, such as: 60/40, 40/20, 20/10.
  • Optical density (D) is defined as the logarithm of the reciprocal of transmittance (T): D=log(1/T) or T=10(-D). Conventional optical density is shown in the table above, if required Other indicators can be achieved.

Tinted Glass Filter Applications

Stained Glass Filter Types

Cut-off color filter glassSelective Absorption Color Filter GlassNeutral filter glass
UV glassUV glassIR glassNeutral grey UV glass
Gold (yellow) glassPurple glassProtective glass
Orange glassBlue glassHeat-absorbing glass
Red glassGreen glassMulti-band calibration glass
Infrared glassGold (yellow) glassSunroof glass
Orange glassColor temperature glass (warm up)
Red glassColor temperature glass (cooling)


AttributesSpecification parameters
MaterialStained Glass Filter
Dimensional tolerance (mm)+0.0/-0.2 (General), +0.0/-0.05 (High Precision)
Thickness tolerance (mm)±0.2 (General), ±0.05 (High Precision)
Clear Aperture>80% (Small Size), >95% (Large Size)
Parallelism1 min. (General), 3 sec. (High Precision)
Surface Quality60/40 (General), 10/5 (High Precision)
Surface (per 25mm@633nm)λ (General), λ/10 (High Precision)
Chamfer (face width x 45.)<0.25mm
CoatingUncoated, Dielectric AR Coating, Dichroic Filter Coating, etc.


Apexel Optics Tinted Glass Filters can be applied to:

  • Photography equipment
  • Instrumentation
  • Optical equipment
  • Medical equipment
  • teaching facility
  • UV analyzer
  • Financial equipment
  • Lighting installations for airports
  • Military equipment
  • Institute of Science

Interference filter


AttributesSpecification parameters
MaterialColor filter glass or optically coated glass
Regular diameter (Φmm)12.0, 15.0, 25.0, 25.4, etc.
Regular thickness (mm)2.0 ~ 10.0
Diameter tolerance (mm)±0.2
FWHM (nm)10 ~ 80
Wavelength Tolerance (nm)±2 ( 10nm FWHM)
Surface Quality80/50 (General), 40/20 (High Precision)
Wavelength (nm)220, 254, 265, 280, 295, 313, 340, 365, 405, 340, 380, 400,
405, 430, 450, 492, 497, 510, 524, 530, 546, 550, 555, 578,
590, 592, 600, 612, 620, 630, 690, 700, 750, etc.

Something else:

  • Interference filters of other sizes or shapes can be customized if required;
  • The conventional thickness is 2.0-5.0nm, and the customized thickness can reach 2.0-10.0nm;
  • The conventional diameter tolerance is ±0.2mm, and higher precision can be achieved if necessary;
  •  The conventional FWHM (transmission wavelength range, defined by the half value of the maximum width of the transmission curve) is 10nm-80nm, which can be extended to 1-100nm if necessary.
  •  The normal wavelength tolerance is ±2nm, when the FWHM is 10nm, higher accuracy can be achieved according to customer requirements.
  •  The conventional surface quality is 80/50, and higher precision can be achieved if required, such as 60/40, 40/20.
  •  The wavelength range in different applications is different, generally divided into ultraviolet band UV (200nm-399nm), visible light band (400nm-700nm), infrared band (750nm-2500nm), please inform you the wavelength range you need to apply .

Dielectric Coated Filters

Apexel Optics offers dielectric coated filters made of optical materials such as colored glass, BK7, fused silica, sapphire, etc.
This filter includes bandpass filter, dichroic filter, longpass filter and shortpass filter. The transmission range of wavelengths is determined by the customer, and high transmission at specified wavelengths can be provided upon request.

AttributesSpecification parameters
MaterialOptical glass
Regular diameter (Φmm)10.0, 12.7, 15.0, 20.0, 25.4, etc.
Normal thickness (mm)0.2 ~ 20.0
Diameter Tolerance (mm)±0.2 (General), +0.0/-0.05 (High Precision)
Surface Quality80/50 (General), 40/20 (High Precision)
Wavelength (nm)Upon request
Optical Density0.04, 0.1, 0.2, 0.3, 0.4, 0.5, 0.8, 1.0, 2.0, 3.0, 4.0, etc. 0.1, 0.2, 0.3, 0.5, 0.8, 1.0, 2.0, 3.0, 4.0, etc.
CoatingDielectric coated AR, HR, PR, etc.


Something else:

  • The material is colored glass, BK7, fused silica, sapphire, etc,
  • If required, this filter can be customized in different sizes and shapes,
  • UV (200nm-399nm), VIS (400nm-700nm), IR (750nm-2500nm) and other bands can be used,
  • Please contact us for more details.

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