Scatter Measurements

CASI Scatterometer

The CASI Scatterometer Lab

Scatter measurements are useful for a huge variety of applications.  They can be used as a measure quality for optical surface finishes and films, as a way to characterized point defects and are often needed as input data for programs that predict signal limiting scatter levels in complex optical systems. TSW offers measurements from the near-UV to the mid-IR using the CASI Scatterometer shown in the above figure. Other wavelengths  are available from TSW through arrangements with other labs.  TSW operates both CASI and TTS scatterometers in clean environments.  The CASI is capable of making both transmissive and reflective scans within the incident plane and can make limited measurements out of the incident plane as well.  The TSW CASI Labs currently operate at over 20 wavelengths between 325 nm in the near UV and 10.6 microns in the mid-IR, many with full polarization control on the source and optional full polarization filtering on the receiver.  The noise floor is limited by Rayleigh scatter from the air, or about 10-8/sr. Additional wavelengths will be added depending on market requirements.  Samples may be flat or gently curved, and may vary in size from a few millimeters to larger than a 300 mm wafer.  Results are presented in BRDF, ARS (CCBRDF) and DSC format depending on the sample.  The sample stages can be moved in repeatable one micrometer steps and the illuminated spot can be varied from several millimeters to ten micrometers. TSW sells the TTS scatterometer for Fraunhofer. A unit is installed at TSW and used for both demonstrations and commercial measurements. The system takes nearly full (or definable partial) hemispherical measurements in both transmission and reflection at wavelengths of 405 nm, 532 nm and 640 nm. The noise floor is limited by Rayleigh air scatter at all three wavelengths. Sample size is limited to about a six inch diameter.  

TTS Drawing TTS at TSW  

The Table Top Scatterometer used for the hemispherical angle resolved scatter measurements is shown with the light shield off on the left and in the TSW lab on the right with the doors open. 

The variation in requirements (number of samples and scans) makes it impossible to price measurements on a simple per scan basis, so each job is quoted separately.  Prices generally fall in the $250 to $350 per incident plane scan and are more expensive for full hemispherical scans.  Please call or email with details to get a quote.  TSW can also arrange for measurements at different wavelengths (1.06 mm, 1.5 mm 3.39 mm, and 10.6 mm to name a few) at another lab.  If you need help with what should be measured, or have another consulting job with TSW, it may be to your benefit to do one stop shopping at TSW for all of your measurements and analysis.