stokes ellipsometer LSE description
The Stokes Ellipsometer LSE is a continuation of an entirely new line of ellipsometers based on the advanced StokesMeter™ technology (previous winner of Photonics Spectra and R&D 100 best new products awards). The units' simple design offers unprecedented ease of use and instantaneous measurement at a cost under $20K.

This  ellipsometer uses advanced StokesMeter™ technology with no moving parts and no modulators to quickly and accurately determine the complete polarization state of the 6328Å laser measuring beam at a 70° incidence angle. The space-saving design features a small footprint yet it can accommodate large samples up to 300mm wide. The sample stage can be easily moved by hand to measure any point on the sample surface. The sample table includes a manual tilt and table height adjustment which is set using an alignment screen on the computer.

Windows VISTA/XP/2000 LGEMP included software can measure the top layer film thickness and film refractive index on a substrate or on 1, 2, or 3 known sub-layers. The films can be transparent or absorbing. This durable integration of hardware and software is fast, reliable and easy to use.

Extremely precise, stable and low cost the model LSE Stokes Ellipsometer represents an excellent value in a basic ellipsometer.

high speed film thickness measuring system measures in less than a second!

The LSE based on advanced StokesMeter™ technology, offers instantaneous measurement at a low cost and is upgradeable to the Imaging Waferskan, Two or Three Wavelength ellipsometers.

features

• Tilt-free, focus free, hands-off operation for similar wafers.
• Fastest possible instrument for thin film measurement.
• Trouble-free, no moving parts advanced StokesMeter™ measurement head.
• Measures complete state of polarization useful for rough,scattering samples.
• Accurate, stable measurements using spectrally precise laser ellipsometry.
• Simple, compact tabletop instrument - competitively priced.

description of stokesmeter™ technology
This advanced device uses no moving parts and no modulators to quickly and accurately determine the complete polarization state of the measuring beam.

The diagram above shows the StokesMeter™ photopolarimeter for the simultaneous measurement of all four Stokes parameters of light. The light beam, the state of polarization of which is to be determined, strikes, at oblique angles of incidence, three photodetector surfaces in succession, each of which is partially spectrally reflecting and each of which generates an electrical signal proportional to the fraction of the radiation it absorbs. A fourth photodetector is substantially totally light absorptive and detects the remainder of the light. The four outputs thus developed form a 4x1 signal vector I which is linearly related, I=AS, to the input Stokes vector S. Consequently, S is obtained by S=A(-1)I. The 4x4 instrument matrix A must be nonsingular, which requires that the planes of incidence for the first three detector surfaces are all different. For a given arrangement of four detectors, A can either be computed or determined by calibration.

technological advantage
The stable, compact StokesMeter™ replaces a typical rotating analyzer assembly consisting of a drum, prism, encoders, switches, motor and detector and their associated electronics. In addition, the waveplate mechanism on the polarizer arm, is eliminated. This results in a fast, precise, no moving parts ellipsometer.

An outstanding feature is the Stokes Ellipsometer's compensation for small changes in angular beam deviation caused by sample out-of-flatness. This permits fast, uninterrupted measurement over the entire wafer surface without the need to pause to correct for focus and tilt. When scanning similar samples, tilt-free, focus-free operation is the obvious benefit.

The LSE model ellipsometer includes the LGEMP Windows software, PCI interface card and cable.  A Windows VISTA/XP/2000 computer with an available PCI slot is required and is not included. 

LSE can be equipped with the following laser options:

 LASER SUBSTITUTION

LS405    Substitutes 405 nm  Blue laser diode in place of 633 nm HeNe Gas Laser  $13K
LS544    Substitutes 544 nm Green HeNe Gas laser in place of 633 nm HeNe Gas Laser  $4K
LS830    Substitutes 830 nm laser diode in place of 633 nm HeNe Gas Laser $9K

ADD ADDITIONAL LASER FOR A 2 WAVELENGTH ELLIPSOMETER 

L2W405    Adds 405 nm Blue Laser Diode to 633 nm ellipsometer $21K
L2W544    Adds 544 nm Green HeNe Gas Laser to 633 nm ellipsometer $15K
L2W830    Adds 830 nm laser diode to 633 nm ellipsometer  $18K 

ADD TWO ADDITIONAL LASERS FOR A 3 WAVELENGTH ELLIPSOMETER  

L3W405.544   Adds 405 Laser Diode and 544 Green Gas Laser to 633 nm ellipsometer $26K
L3W405.830   Adds 405 Laser Diode and 830nm laser diode to 633 nm ellipsometer $29K          
L3W544.830   Adds 544 Green Gas Laser and 830nm laser diode to 633 nm ellipsometer $23K

L-SCAT SOLAR CELL / SCATTERING SAMPLE MEASUREMENT OPTION  $2K

Rough scattering samples common in the solar cell industry are difficult to measure accurately with most ellipsometers because of the loss of signal strength and depolarization of the measurement beam. Although there are ways to boost the signal strength and capture more scattered light, dealing with depolarization is much more difficult and requires the determination of the complete state of polarization namely the measurement of the 4 stokes parameters S0, s1, s2, s3. Gaertner Stokes Ellipsometers do this naturally as our StokesMeterä polarimeter is used as the ellipsometer's analyzer. This gives Stokes Ellipsometers the unique ability to instantly separate the polarized from the unpolarized components of the measuring beam thereby delivering a highly accurate measurement of film thickness and index based only on the totally polarized component of light. In addition, the L-SCAT scatter option includes a hardware modification to capture more of the scattered light from rough, textured surfaces and a program display of the degree of polarization P.  Keep in mind however that some samples are simply too rough and scatter too much light to be measured ellipsometrically.

stokes ellipsometer LSE specifications

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