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Hi All,
We have a DLP7000UV DMD. We use a UV source with spectrum 320-500nm. Previously after reflection from DMD we used to get 25mW/cm^2 intensity when measured with 365nm sensor radiometer, but now with the same setting we are getting only 7mW/cm^2. We checked our UV source and it is working normal. Has the reflectivity of the DMD decreased? We noticed that we were violating the recommended UV range of 365-420nm for the DMD. But what exactly happened to our DMD? And is there any way we can fix it? Also, previously I noticed that the image loaded on the DMD used to look very bright white, but now it looks a bit greyish to me (it is not as bright as before but I am not 100% sure about it). I have attached our UV spectrum image for your reference. I am also attaching a picture of an image loaded on to the DMD. The white rectangular part on the DMD is our image; does the image look bright enough for you?
Thank you,
Nishedh
Nishedh
The Optical source you are using is rated at 200 W and > 30 W/cm^2 at its output.
The DLP7000UV is rated for max 2.5 W/cm^2 363-400 nm which is ~3.7 W total measured at the DMD window.
Have you designed your illumination optics between the OmniCure S2000 output to reduce the optical power to operate within the DLP7000UV data sheet limits?
Also, you need to ensure the DMD is operated with the micromirror array at 20-30 Deg. C when used with light sources below 420 nm.
Please see our application note Considerations Using TI DLP® Technology in UVA (363 – 420 nm) www.ti.com/.../dlpa060
Nishedh
How are you reducing the optical source power (OmniCure S2000 output) to have a typical 25mW/cm^2 output from the DLP7000UV.
What is the effective power density of the sourced measured at the DMD window ?
Reduction in DMD efficiency is typically caused by operating the DMD with UV power density outside of the data sheet limits, this effect will be greatly accelerated if the the DMD mirror array temperature is not operated in side the data sheet limits of 20-30 Deg. C.
See section 9.1.1 and figure 18 of the DLP7000UV data sheet http://www.ti.com/lit/ds/symlink/dlp7000uv.pdf
Carey
Carey,
Attached is a schematic representation of our system. The optical power source can be varied from 0-100%; if we keep it at 50% we get 25mW/cm^2 UV intensity at our stage. The intensity on DMD mirror may also be around the same value ( I think). Also, we are planning to use a 365 nm filter between the source and our new DMD mirror. I have attached its spectrum output here. Do you think we can use our DMD at 25mW/cm^2 intensity with this filter? Note: though the spectrum has peak at 365 nm, it also has some shorter wavelength UVs, so will that affect our DMD again? Please suggest.
Thank you,
Nishedh
Carey,
We have not measured intensity at the DMD mirror. We only measure it at the stage. Also, what do you think about the above attached spectrum of 365nm filter? What maximum intensity at the DMD is safe to use with that spectrum? Please suggest. We are getting our new DMD soon and we want to use that filter if it is safe.
One more thing: can we use non contact infrared thermometer to measure DMD temperature?
-Nishedh