Application Report
DLPA031E – May 2012 – Revised December 2019

Wavelength Transmittance Considerations forDLP® DMD Window
ABSTRACTThe use of DLP technology in advanced imaging and exposure systems such as lithography, additive
manufacturing, spectroscopy, optical networking, 3D scanning, and medical systems is growing. Various
optical factors must be taken into consideration to facilitate these emerging applications.
The digital micromirror device (DMD) efficiency observed in a specific application depends on equipmentspecific design variables such as illumination wavelength, illumination angle, projection aperture size,
overfill of the DMD micromirror array, and so on. Overall optical efficiency of each DMD can generally be
estimated as a product of window transmission (2 passes), diffraction efficiency, micromirror surface
reflectivity, and array fill factor. The first three factors depend on wavelength of the illumination source.
This application report provides information specifically on transmittance of DMD windows in different
regions of the electromagnetic spectrum.

Trademarks
DLP is a registered trademark of Texas Instruments.
All other trademarks are the property of their respective owners.

1Introduction
DLP technology uses two types of materials for DMD windows.
• For Type-A DMDs the window uses Corning 7056.
• For all other DMDs the window material is Corning Eagle XG.
Both window types have an anti-reflective (AR) thin film coating on both the top and the bottom of thewindow glass material. AR coatings reduce reflections and increase transmission efficiency.
The DMD windows are designed for four different transmission regions.
• Ultraviolet (UV) light: 355 to 420 nm• Visible light: 400 to 700 nm• Near infrared (NIR) light: 700 to 2500 nm• Near infrared (NIR2) light: 800 to 2000 nm
The DLP portfolio of chips offers DMDs that span these wavelength regions to enable advanced lightcontrol in diverse end equipment designs. DMDs designated as UV devices therefore have windows with
AR coatings designed to be more transmissive for ultraviolet wavelengths. Similarly, DMDs designated asNIR devices have windows with AR coatings designed to be more transmissive for NIR wavelengths.
Many devices in the DLP portfolio are designed for display applications and therefore considered visible
DMDs, having windows with AR coatings designed to be transmissive for visible wavelengths.
The measured data provided in the following sections reflects a typical single-pass transmittance throughboth top and bottom AR coated window surfaces with random polarization. The angle of incidence (AOI) of0° is measured perpendicular to the window surface, unless mentioned otherwise. With an increase in thenumber of window passes, the efficiency would decline.
NOTE:

The curves shown are typical performance and not minimum specified limits or ensuredvalues.

DLPA031E – May 2012 – Revised December 2019
Submit Documentation Feedback

Wavelength Transmittance Considerations for DLP® DMD Window

Copyright © 2012–2019, Texas Instruments Incorporated

1

Corning 7056 Window Transmittance Curves2

www.ti.com

Corning 7056 Window Transmittance Curves
The window transmission response curves in this section apply to Type-A DMDs in their specified
illumination wavelength regions. Figure 1 shows the UV window and visible window transmittancemeasured perpendicular to the window surface. Figure 2 and Figure 3 are the zoomed-in views of thetypical visible and UV AR coated window transmittances in their maximum transmission regions.

Figure 1. Corning 7056 Visible and UV Window Options
The visible window is optimized for 400 to 700 nm wavelengths. The UV window is optimized for 355 to420 nm wavelengths.

Figure 2. Corning 7056 Visible Window Transmittance (Visible Region)

2Wavelength Transmittance Considerations for DLP® DMD Window

DLPA031E – May 2012 – Revised December 2019
Submit Documentation Feedback

Copyright © 2012–2019, Texas Instruments Incorporated

Corning 7056 Window Transmittance Curves

www.ti.com

Figure 3. Corning 7056 UV Window Transmittance (UV Region)

DLPA031E – May 2012 – Revised December 2019
Submit Documentation Feedback

Wavelength Transmittance Considerations for DLP® DMD WindowCopyright © 2012–2019, Texas Instruments Incorporated

3

Corning Eagle XG Window Transmittance Curves

3

www.ti.com

Corning Eagle XG Window Transmittance Curves
The window transmittance for the different AR coated Corning Eagle XG windows are shown in Figure 4 .

Figure 4. Corning Eagle XG Visible, NIR, and NIR2 Window Options
The visible Corning Eagle XG window transmission data in Figure 5 applies to visible DMDs that are not inType-A packages. It shows the typical transmittance observed in the broadband visible region isapproximately 97% (single-pass through two window surfaces).

Figure 5. Corning Eagle XG Visible Window Transmittance
The NIR Corning Eagle XG window transmission data in Figure 6 applies to the DLP4500NIR andDLP2010NIR DMDs. The typical transmittance observed in the broadband NIR region is approximately
96% for most of the region (single-pass through two window surfaces), with a dip toward 90% as it nears
2500 nm.

4Wavelength Transmittance Considerations for DLP® DMD Window

DLPA031E – May 2012 – Revised December 2019
Submit Documentation FeedbackCopyright © 2012–2019, Texas Instruments Incorporated

Corning Eagle XG Window Transmittance Curves

www.ti.com

Figure 6. Corning Eagle XG NIR Transmittance (NIR Region)
The NIR2 Corning Eagle XG window transmittance data shown in Figure 7 applies to the DLP650LNIR
DMD. The typical transmittance observed in the broadband NIR region is approximately 97% for most ofthe region (AOI = 0°, single-pass through two window surfaces).

Figure 7. Corning Eagle XG NIR2 Window Transmittance (NIR Region)

DLPA031E – May 2012 – Revised December 2019
Submit Documentation Feedback

Wavelength Transmittance Considerations for DLP® DMD WindowCopyright © 2012–2019, Texas Instruments Incorporated5Revision History

www.ti.com

Revision History
Changes from D Revision (October 2018) to E Revision ............................................................................................... Page
•Updated UV Window Transmission graph to include 24° and 30° AOI ............................................................ 3

Changes from C Revision (March 2014) to D Revision .................................................................................................. Page•••••••

Removed visible window transmittance data at AOI = 30° from Figure 1. ........................................................ 2
Extended highlighted region to 400 to 700 nm Figure 2. ............................................................................ 2
Changed x-axis of Figure 3 to 300 to 450 nm. ....................................................................................... 3
Changed x-axis of Figure 4 to 350 to 2000 nm, added data for NIR2 at AOI=0° and removed visible AOI=30° data. ..... 4
Changed highlighted region of Figure 5 to 400 to 700 nm. ......................................................................... 4
Changed x-axis of Figure 6 to 700 to 2500 nm. ...................................................................................... 5
Added Figure 7. ........................................................................................................................... 5

Changes from B Revision (November 2012) to C Revision ........................................................................................... Page••

Updated Figure 4 .......................................................................................................................... 4
Added Figure 6 ............................................................................................................................ 5

Changes from A Revision (October 2012) to B Revision ............................................................................................... Page••

Changed wavelength From: (mm) To: (nm) ........................................................................................... 2Changed wavelength From: (mm) To: (nm) ........................................................................................... 3

Changes from Original (May 2012) to A Revision ........................................................................................................... Page••••6

Added visible window transmittance data at AOI = 30° to Figure 1 ................................................................
Updated figure 2 ...........................................................................................................................
Added Corning eagle XG visible window transmission data at AOI = 30° .........................................................
Updated Figure 5 ..........................................................................................................................

Revision History

2244

DLPA031E – May 2012 – Revised December 2019
Submit Documentation FeedbackCopyright © 2012–2019, Texas Instruments IncorporatedIMPORTANT NOTICE AND DISCLAIMERTI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATASHEETS), DESIGN RESOURCES (INCLUDING REFERENCEDESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS”
AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANYIMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRDPARTY INTELLECTUAL PROPERTY RIGHTS.
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate
TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicablestandards, and any other safety, security, or other requirements. These resources are subject to change without notice. TI grants youpermission to use these resources only for development of an application that uses the TI products described in the resource. Otherreproduction and display of these resources is prohibited. No license is granted to any other TI intellectual property right or to any third
party intellectual property right. TI disclaims responsibility for, and you will fully indemnify TI and its representatives against, any claims,damages, costs, losses, and liabilities arising out of your use of these resources.
TI’s products are provided subject to TI’s Terms of Sale (www.ti.com/legal/termsofsale.html) or other applicable terms available either onti.com or provided in conjunction with such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicablewarranties or warranty disclaimers for TI products.
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2019, Texas Instruments Incorporated