Annular Aperture Obstruction Targets

Obstruction Diameters Ranging from 50 µm to 1700 µm
Pinhole Diameters Ranging from 100 µm to 2000 µm
Blocking Region with Optical Density ≥ 6
0.5 mm Thick Quartz Substrate in Ø1" Aluminum Housing

R1DF100

Annular Aperture Target
Obstruction Diameter = 100 µm
Pinhole Diameter = 1000 µm

Application Idea

R1CA2000 Obstruction Target Mounted in a CXY1Q Translation Mount with Quick-Release Plate

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Features

Increase Contrast when Imaging Biological Systems
Filter Out Lower Order Spatial Modes
0.5 mm Thick Quartz Substrate
Blocking Region (OD ≥ 6) Created Using a Chrome Mask
AR Coating Over Chrome Mask to Minimize Back Reflections
Aluminum Housing with a 1" Outer Diameter

Thorlabs' Annular Aperture Obstruction Targets (AAOTs) are ideal for increasing the contrast when imaging biological systems or filtering out lower order modes. Each AAOT is characterized by the ratio (ε) between the obstruction diameter (OD) and the pinhole diameter (PD). Thorlabs offers Annulus Aperture targets that are designed with either a constant 1 mm pinhole diameter for high-pass spatial filtering applications, or a constant ε ratio for confocal microscopy applications.

They are fabricated from 0.5 mm thick quartz glass substrate that has high transmission in the 400 - 2200 nm wavelength range. The clear aperture annulus is created using a chrome mask with an optical density ≥ 6 that blocks light from being transmiitted though the inner obstruction target and outer obstruction region. The AAOT is then mounted within a housing that has a 1" outer diameter for mounting within our translation mounts for Ø1" optics, as shown in the image above. The glass substrate is mounted with the chrome mask facing towards the engraved side of the housing. To minimize back reflections, we recommend having the AR-coated chrome mask facing the light souce when used.

Posted Comments:

user (posted 2019-11-12 01:28:54.313)

Hello. Can I purchase blank disks? I want to purchase disks without an annular structure at the center. Best regards, Sang.

YLohia (posted 2019-11-12 12:24:45.0)

Hello Sang, thank you for contacting Thorlabs. Custom items can be requested by emailing techsupport@thorlabs.com. We will reach out to you directly to discuss the possibility of offering this.

h.wu (posted 2017-11-29 14:35:26.623)

Could you make customized annular aperture obstruction targets for us?

tfrisch (posted 2017-12-12 04:32:36.0)

Hello, thank you for contacting Thorlabs. We are able to offer a new size of Annular Obstruction Target. This would require a new master to be made and can be cost prohibitive for low quantities. I will reach out to you directly to discuss a formal quote.

kwjae92 (posted 2017-11-06 01:42:06.177)

Hi, my name is woojae Kang and i have a question about annular aperture. Could I make a custom size annular aperture ? I want ~10mm PD and ~8-9mm OD. Thanks.

tfrisch (posted 2017-12-19 04:54:32.0)

Hello, thank you for contacting Thorlabs. A custom size would require a new master which can be cost prohibitive for low quantities. I will reach out to you directly to discuss a formal quote.

aphillips (posted 2017-07-27 15:22:53.21)

I'm looking for annular aperture obstruction targets in a 1/2" housing. What are our options? Can the targets be easily removed from the 1" housing and placed in a custom housing?

tfrisch (posted 2017-08-16 10:03:41.0)

Hello, thank you for contacting Thorlabs. We can provide unmounted versions as a custom. We will reach out to you with a quote.

dan.reynolds (posted 2017-01-06 08:40:40.773)

I'm looking for a high pass filter for a Fourier optics set and one of these annular apertures would fit the bill nicely. However, I might have higher spatial frequencies that are more than 2mm from the center. Could you make one of these with a 15mm pinhole diameter and somewhere between 100 to 3000um obstruction diameter?

tfrisch (posted 2017-01-06 11:12:46.0)

Hello, thank you for contacting Thorlabs. I will reach out to you directly about the specific requirements for your application.

user (posted 2016-04-15 11:23:55.733)

http://www.thorlabs.co.jp/images/tabimages/Annular_Aperture_Target_Equation_D1-182.gif e should be (Pinhole)/(Obstruction)

besembeson (posted 2016-04-15 04:38:05.0)

Response from Bweh at Thorlabs USA: We define this in this case to be the inverse. Please contact me at techsupport@thorlabs.com if you have any questions or need some clarifications.

Obstruction Targets: Annular Aperture, 0.05 or 0.10 Ratio

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Close-Up Photo of an Obstruction Pinhole
OD: Obstruction Diameter
PD: Pinhole Diameter

Constant Pinhole Diameter of 1 mm
Obstruction Diameters of 50 µm or 100 µm
Ø1" Housing can be Mounted in Many of our Translation Mounts for Fine Alignment
Ideal for High-Pass Spatial Filtering Applications
Can be Used in Our Pre-Assembled Spatial Filter System

These Annular Aperture Obstruction Targets have an obstruction-to-pinhole ratio (ε) of either 0.05 or 0.10, making them ideal for use as high-pass or edge-enhancement filters. When the Fourier plane is imaged onto the filter, the center region, which contains Gaussian light (TEM₀₀), will become blocked by the center obstruction. This allows the higher order modes of the Fourier plane, which contain diffraction information, to pass through and form the image. This will cause an overall loss of light intensity and generalized, smooth features, but it will enhance any sharp lines or boundaries.

Shown to the right is a close up photo of an obstruction pinhole with the pinhole diameter (PD) and obstruction diameter (OD) labeled. The chrome-masked area appears black, and light is transmitted through the clear aperture.

Item #	ε Ratio^a	Obstruction Diameter	Pinhole Diameter	Annular Aperture Concentricity		Glass Thickness
Item #	ε Ratio^a	Obstruction Diameter	Pinhole Diameter	with Respect to Housing^b	with Respect to Substrate^c	Glass Thickness
R1DF50	0.05	50 µm	1 mm	<0.41 mm	≤216 µm	0.5 mm
R1DF100	0.10	100 µm	1 mm	<0.41 mm	≤216 µm	0.5 mm

Ratio of the Obstruction Diameter to the Pinhole Diameter (See Photo to the Above Right)
Concentricity of the Annulus with Respect to the Outer Diameter of the Quartz Glass Substrate
Concentricity of the Annulus with Respect to the Outer Diameter of the Aluminum Housing

Obstruction Targets: Annular Aperture, 0.85 Ratio

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Click to Enlarge
Close-Up Photo of an Obstruction Pinhole
OD: Obstruction Diameter
PD: Pinhole Diameter

Constant ε Ratio of 0.85
Ø1" Housing can be Mounted in Many of our Translation Mounts for Fine Alignment
Ideal for Confocal Microscopy Applications
Can be Used in Our Pre-Assembled Spatial Filter System

These Annular Aperture Obstruction Targets have a constant obstruction-to-pinhole ratio (ε) of 0.85, making them ideal for increasing the lateral spatial resolution within confocal imaging systems. These filters are designed to be placed directly in front of the output of a light source such as a fiber-coupled laser. The system should be aligned so that the first bright diffraction spot of the light source is larger than the pinhole diameter of the annular aperture.

These annular apertures are often used in confocal and two-photon excitation microscopy to increase the lateral resolution of the imaging system or in confocal theta fluorescence microscopy to increase the lateral and axial resolution of the imaging system.

Item #	ε Ratio^a	Obstruction Diameter	Pinhole Diameter	Concentricity		Glass Thickness
Item #	ε Ratio^a	Obstruction Diameter	Pinhole Diameter	with Respect to Housing^b	with Respect to Substrate^c	Glass Thickness
R1CA100	0.85	85 µm	100 µm	<0.41 mm	≤216 µm	0.5 mm
R1CA200		170 µm	200 µm
R1CA300		255 µm	300 µm
R1CA1000		850 µm	1000 µm
R1CA2000		1700 µm	2000 µm

Ratio of the Obstruction Diameter to the Pinhole Diameter (See Photo to the Above Right)
Concentricity of the Annulus with Respect to the Outer Diameter of the Quartz Glass Substrate
Concentricity of the Annulus with Respect to the Outer Diameter of the Aluminum Housing

The R1CA100, R1CA200, and R1CA300 will be retired without replacement when stock is depleted. If you require these parts for line production, please contact our OEM Team.

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Annular Aperture Obstruction Targets

Features

Obstruction Targets: Annular Aperture, 0.05 or 0.10 Ratio

Obstruction Targets: Annular Aperture, 0.85 Ratio