Design and manufacture of diffractive
optical elements

High Efficiency Beam Splitters

High Efficiency 1x2 and 2x2 beam splitters

Double Spot 1x2 and Quattro Spot 2x2 beam splitting is a highly useful practice in many applications, including lithography, perforation, cutting and other material processing applications.
Although our standard Double Spot 1x2 beam splitter (DS) and Quattro Spot 2x2 splitters are highly robust and offer up to 81% and 64% efficiency, respectively, for demanding application the existence of even 1% input power in undesired higher orders is not tolerable.

For these sensitive applications, and for costumers interested in high efficiency, Holo/Or has developed a family of novel diffractive beam splitters: High Efficiency Double Spot (HEDS 1x2) and High efficiency Quattro Spot (HEQS 2x2).

Holo/Or's High Efficiency splitters are a special sub-aperture based diffractive optical element (DOE) capable of splitting a beam into Double Spot 1x2 or Quattro Spot 2x2 spots with 97% efficiency and almost no power in undesired orders.

Features
  • High efficiency (~97%)
  • Low undesired orders (<0.2% input for
    highest undesired)
  • Tunable splitting ratio
  • High laser damage threshold
  • Available in 193nm-10600nm wavelengths
Applications
  • Lithography/Thin film
  • Flat panel structuring
  • Fine cutting/Marking
  • Perforation

Figure 1: HEDS compared to Standard Double Spot energy distribution

High Efficiency Double Spot

HEDS operate with a sub-aperture approach, and are therefore sensitive to centering and have an effect on the spot shape. The spot size in the splitting axis is increased (spot becomes slightly elliptical), and this effect is felt only for single-mode lasers (low M2).

Spot size is defined by the formula:
Spot Size Formula


Where:
DLSM - beam size for M2=1
EFL - Effective focal length
λ - Wavelength
D - Input beam size M2 - M2 value of input laser beam (beam quality)

For low M2(<~4) the beam in focus will have some ellipticity because of added 0.75.
For higher M2 values the spots will become symmetrical.

HEQS 2x2 splitters increase M2 symmetrically, so no ellipticity will appear, but spot size will increase for low M2 (single mode) lasers.
HEDS (High Efficiency Double Spot) Standard Double Spot 2D
HEDSStandard Double Spot (DS)
HEQS (High Efficiency Quattro Spot)
Comparison between standard DS/2x2 and HEDS/HEQS
Standard DS/2x2HEDS/HEQS
Efficiency 81%, 64% ~97%
Sensitivity to alignmentNoYes
Angle precisionPerfectPerfect
UniformityPerfectAlignment dependent*
Presence of undesired ordersYesVery low
Beam size sensitivityNoNo

*depends on input beam; for single mode input, centering accuracy of +/- 0.5% diameter gives 2% deviation between orders.
@Copyright 2015, Holo/Or Ltd. P.O.B 1051, Rehovot, 76114 Israel
Phone: +972 (8)-9409687/8, Fax: +972 (8)-9409606

Home | Products | Applications | Publications | Capabilities | Contact us | Site Map