Achromatic Waveplates

Featured Product from Hangzhou Shalom Electro-optics Technology Co., Ltd.

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Features:

  • Off-the-shelf and customized modules are available

  • Flat retardance over a certain wavelength range

  • Two kinds of materials: Quartz and MgF2

  • Standard wavelength band options: 450-650nm, 690-1200nm, and 900-2000nm

  • NOA61 cemented or Air spaced design

  • Super Achromatic Waveplates are also offered

 

An Achromatic Waveplate is a special kind of Zero Order waveplate, comprised of two waveplates made using two different birefringent materials (e.g. crystal quartz and magnesium fluoride). The existence of chromatic dispersion greatly affects the refractive indices of materials. The two birefringent materials which construct the achromatic waveplates have complementary birefringent properties that could attenuate the chromatic dispersion effects so that excessive shifts of retardation over wavelength change in the first waveplate could be counterbalanced by the second waveplate. This results in a virtually flat response of phase delay over a broad wavelength band (usually hundreds of nanometers), therefore achromatic waveplate is an excellent choice for applications orienting tunable laser sources, femtosecond laser systems, spectroscopes, and other systems concerning broadband light sources.

The two most common phase retardation values are lambda/2 and lambda/4 retardation, half waveplates could be applied to the rotation of vertical polarization and horizontal polarization, whilst quarter waveplates could be used for conversion of linear and circular polarization. Hangzhou Shalom EO offers Achromatic Half Waveplates and Achromatic Quarter Waveplates made from single crystal quartz and magnesium fluoride (MgF2), configured with a high-quality AR coating. The two waveplates are either cemented using NOA61 (Norland Optical Adhesive 61) or with an architecture of an air gap in between. NOA61 is a high-performance adhesive with great bonding strength, high heat resistance, and excellent clarity to support optical applications under various operation conditions, and Shalom EO only applies the glue outside the clear aperture of the waveplates. Achromatic waveplates with an air-spaced design are coated on all faces, then mounted on opposite sides of a spacer, and placed within a cell, to form an air gap between the quartz waveplate and the MgF2 waveplate. The air-spaced modules have particularly promoted damage threshold greater than 500MW/cm^2, and are adaptive to high-power lasers.

Off-the-shelf achromatic waveplates are available for online shopping in Shalom EO. The standard achromatic waveplates are of half or quarter retardation, with three optional wavelength ranges: 450-650nm, 690-1200nm, 900-2000nm covering the visible, and a portion of the infrared Spectral. Fast despatch and economized pricing is guaranteed. Incidentally, If you have any other specific requirements, Shalom EO also provides custom services where all the parameters could be tailored to suit your demand. 

 

FAQs about How to Use A Waveplate:

Below are some frequent problems you might encounter during the usage of waveplates. Engineers from Shalom EO here offer a few usful tips.

How to find the axes of a waveplate?

Finding the fast axis of each waveplate is a critical step when using the waveplates. The mounted waveplates offered by Shalom EO are all designed with their fast axes indicated as a straight light on the mount. While the fast axis of the unmounted versions is all marked directly on the waveplates. However, if it happens that the axes are not indicated or the indications are blurred, there is a simple method to help you find the axes which apply for waveplates with all values of retardations. First, place a polarizer in front of the laser device, tilt the polarizer until the light is extinct, then interpose the waveplate between the laser device and the polarizer, rotate the waveplate so that the eventual light output is still extinct——and viola! you have found an axis successfully.

How to make some adjustments?
Additionally, It might happen that you find the waveplates you bought might not produce exactly the intended retardation. There are plenty of reasons: e.g. the waveplates are not designed for your wavelength of interest, or there are external factors such as temperature affecting the retardation. The small deviations could be modified by rotating the plane of polarization towards the fast or slow axis of the waveplate. Moving toward the fast axis reduces the retardation while moving towards the fast axis raises the retardation. Try both directions and keep checking the improvements using polarizers.