Press Release
June 30, 2009
Epson Toyocom Commercializes Wave Plates for Blue Light Spectrum
- New GL series realizes top-notch photostability -
Epson Toyocom Corporation, the leader in crystal devices, has announced the commercial development and volume production, starting June 2009, of the "GL series" of high-performance wave plates(*1) for use in the systems of optical pickups. The GL series is sufficiently photostable to withstand even light in the blue spectrum that is of high-power and high spectral density.
The spread of high-capacity networks, high-definition digital movies and new generations of home gaming systems is heightening demand for faster Blu-ray※1 Disc drives with higher storage capacities, leading to work on higher-power laser diodes (LD) and improvements in optics. Advances in these areas have likewise spawned a need for optical components that exhibit greater photostability.
The GL series of wave plates demonstrate excellent photostability (Figure 2), exhibiting no change in properties even when irradiated for more than 1,000 hours with blue wavelength light having a power density on the order of 1 W/mm²※2. Unachievable with conventional technology, this level of photostability was enabled by Epson Toyocom's original GL bonding technology(*2) for joining quartz plates by means of a glass-like layer.
Moreover, the bonding layer used in GL bonding technology can be made as thin as approximately 100 nm, making for extremely small variations in in-plane wave plate thickness, which translates into dramatically reduced transmitted wavefront aberration(*3) (Figure 3). These wave plates also boast other outstanding optical characteristics, including transmittance.
While the characteristics of these products will enable them to contribute to faster Blu-ray Disc drives with larger storage capacities, Epson Toyocom also plans to use GL bonding technology to develop a lineup of optical devices for projectors and other products that require high photostability and reliability.
※1 Blu-ray is a registered trademark of the Blu-ray Disc Association.
※2 Source: Epson Toyocom research. In optical devices constructed by bonding together quartz or glass base materials.
For product enquiries, please locate your regional Epson Toyocom representative at:
http://www.epsontoyocom.co.jp/english/company/place/kaigai_network.html
About Epson Toyocom
Epson Toyocom Corporation is the global leader in crystal devices, which serve as the heart and pulse for a wide range of electronic products for consumers and industry. Utilizing its innovative hybrid quartz microfabrication technology, QMEMS, Epson Toyocom offers technological expertise in timing, sensing, and optical devices, and maintains its leadership position by providing customer-specific combinations and solutions.
http://www.epsontoyocom.co.jp/english/
(*1) Wave plate
An optical component that alters the polarization of light passing through it. Wave plates may convert linearly polarized light to a state of circular polarization (and vice-versa), or they may convert light vibrating in a vertical direction to light vibrating in a horizontal direction. Used to control the path of light, wave plates are employed in devices such as optical pickups in disk drives, where they are combined with other optical components having functional layers that transmit or reflect laser light with a specific polarization.
(*2) GL bonding technology
Technology for laminating quartz plates together by means of a glass-like material. Whereas adhesives made of organic materials comprise thick layers, GL bonding technology uses inorganic materials in an ultra-thin film as thin as 100 nm to realize optical components that exhibit high photostability and mitigate transmitted wavefront aberration.
(*3) Transmitted wavefront aberration
Deviation of a wavefront from an ideal wavefront after passage through an optical system (if the ideal wavefront is linear, the deviation from linear). The amount of aberration is expressed using the unit for wavelength. In the case of a planar optical component, aberration is produced as a result of factors such as the degree of parallelism, surface roughness and surface distortion.
Figure 1. Typical Structure of This Product
Figure 2. Photostability Test Results for This Product
A wave plate in the new GL series and a wave plate that used the conventional adhesive were irradiated for more than 1,000 hours with blue wavelength light having a power density on the order of 1 W/mm². The changes in physical appearance (1) and the transmitted wavefront aberrations (2) of the two wave plates were then compared.
The GL series shows no signs of heat damage, and wavefront aberration is constant.
| High-performance GL series wave plate | Wave plate with adhesive | ||
|---|---|---|---|
| (1) | Physical Appearance Sample size 3 x 4 mm |
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| (2) | Aerial View of Aberration Measured diameter: 2.0 mm |
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Figure 3. Example of wavefront aberration measurement with a laser interferometer
The images below show the magnitude of wavefront aberration as contour lines. The wave plate laminated with adhesive (right image) exhibits wavefront aberration. The aberrations result from in-plane nonuniformity of the optical path length (expressed by optical thickness and index of refraction x distance) caused by uneven thickness of the bonding layer.
The GL series (left image) exhibits dramatically reduced wavefront aberration as a result of an extremely thin bonding layer with exceptionally small thickness variation.
| High-performance GL series wave plate | Wave plate with adhesive bonding agent | |
|---|---|---|
| Transmitted wavefront images |  |
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