Design and manufacture of diffractive
optical elements

High Power Masks – Precision aperture for high power laser

Contents

Introduction

HOLO/OR has developed a series of projection masks to answer the demand of using such masks with very high powered laser sources in the UV-VIS spectrum. These masks have two different forms: the dielectric mask has a reflective coating that blocks unwanted light, and the transmissive mask uses a diffractive pattern that diffuses this unwanted light at large angles.

Typical Parameters:

Outer Diameter:5 - 100 mm
Aperture ShapeRound, square, multi-aperture, other
Aperture Size10 um - 60 mm
Wavelength spectrum193 - 11000 nm, each element designed for single wavelength
Transfer RegionSmall; sharp edges
SNR~500
Shape size>5 um

Dielectric Reflective Mask

Dielectric masks are Fused Silica substrates patterned by very thin (~1um) reflective coating. The coated part reflects the incoming beam while the uncoated part transmits the beam.


Typical Applications:

  • Micro patterns projection for high power systems
  • UV lithography


Schematic sketch of the optical system:

dielectric mask set up
Fig 1. Typical Set Up


HOLO/OR can design and manufacture a custom dielectric mask to match the customer's needs.

Custom Dielectric Mask
Fig 2.Real measurement of custom Dielectric Mask taken with microscope magnification

Features of Dielectric Mask:

  • High damage threshold
  • Low absorption
  • High reflection (>99%) in reflective part
  • High transmission (>95%) in transparent part
  • Very thin dielectric reflective layer (~1 um)

Transmissive Imaging Mask

Principle of operation:

The Transmissive Mask transmits all incident illumination without any blocking. The pattern to be imaged is a clear mask area that transfers the light without interruption, while the surrounding areas transfer light through a specially designed diffractive pattern which diffuses light in large angles. Placed close to the focal plane of a focusing lens, a pinhole blocks most of the diffused light, so that a high-contrast intensity shape is achieved at the image plane.


Schematic sketch of the optical system:

transmissiv mask set up

Features of Transmissive mask:

  • No danger of reflected light causing damage to optical system
  • ~100% transmission
  • Higher laser damage threshold than for reflective mask
  • Affordable price, similar to that of other diffractive elements

Transmissive Mask elementMeasured Intensity


Standard products

 
Part Number Diameter (mm) Aperture Size (um) Aperture Shape Material
DM-002 11 65 Square Fused Silica
DM-003 11 165 Square Fused Silica
DM-004 25.4 1750 Square Fused Silica
DM-005 25.4 3500 Square Fused Silica
DM-006 25.4 7000 Square Fused Silica
DM-007 25.4 10838 Round Fused Silica
DM-008 20 8428 Round Fused Silica
DM-009 25.4 6200 Round Fused Silica
DM-010 25.4 5680 Round Fused Silica
DM-011 11 4817 Round Fused Silica
DM-012 11 3612 Round Fused Silica
DM-013 11 2408 Round Fused Silica
DM-014 11 4214.9 Round Fused Silica
DM-015 11 3000 Round Fused Silica
DM-016 11 5400 Round Fused Silica
DM-017 85 50075 Square Fused Silica
DM-019 25.4 300 Square Fused Silica
For a quotation of an above Part Number, please specify the wavelength used.

Contact Us for more information or for a custom solution.

@Copyright 2017, Holo/Or Ltd. P.O.B 1051, Rehovot, 7611001 Israel
Phone: +972-89409687/8, Fax: +972-89409606

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