Shortening measurement time of film thickness measurement system

Customer’s situation

A transmission optical system with a condenser lens was used to incident the light into the film thickness measurement system. Because chromatic aberration occurs when focusing by lens, it was difficult to focus the entire light into one point.
They would have wanted to reduce measurement time by eliminating loss of focused light.

Note: What is chromatic aberration caused by transmission optics?
Chromatic aberration is a phenomenon in which the imaging position deviates depending on the wavelength due to the wavelength dependence of the refractive index of the lens material. Therefore, a spherical lens can not focus all wavelengths of light at one point.

Axial chromatic aberration

Axial chromatic aberration


Note: What are the advantage of reflective optics?
Reflective optics are wavelength independent and chromatic aberration does not occur.
Reflective optics are also effective when using light in the ultraviolet region. While lenses have a limited number of materials with high transmittance in the ultraviolet region, metal mirrors have excellent reflectivity in the ultraviolet region.

Advantages of Shimadzu products

★Advantage1: Toroidal mirrors with excellent light focusing
Shimadzu toroidal mirrors are the best reflective optical elements to focus light.
Because the surface of the mirror is toroidal, it can focus the light at one point with suppressing astigmatism caused by spherical mirrors. 
We can also suggest the best specifications for your optical configuration through optical simulation. 

Difference to spherical mirrors

Difference to spherical mirrors


★Advantage2: Original Al coating technology for high reflectivity in the ultraviolet region
Shimadzu’s own Al coating achieves high reflectance even around 200 nm.
Shimadzu Al mirrors are suitable for using in a wide range of wavelengths from the ultraviolet region to the infrared.

Benefits by using Shimadzu products

As a result of using Shimadzu Toroidal mirrors, they were able to develop the new film thickness measurement system with improved measuring speed.
They also were able to increase the incident light in the ultraviolet region and measure thinner film thicknesses.

Customer’s feedback

We had to design within a limited space, but in a short period of time we were able to reach to the best toroidal mirror.
The fact that the mirrors are also used in Shimadzu analytical equipment is building a feeling of safety at quality aspect.

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