Phase Plate Rectangular Beam Profile for Laser Illumination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser arrays used in projection displays often waste light due to their Gaussian intensity profile, which is not optimally suited for uniformly illuminating linear optical modulators, leading to inefficient image formation.
Innovation Solution
The use of a phase plate with notches to modify the Gaussian beam profile into a rectangular profile, achieved through Fourier transform relationships, ensures uniform illumination of the modulator array by focusing the light with lenses, thereby efficiently utilizing the light emitted by laser arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a Gaussian beam is expanded to illuminate a linear modulator array, then uniform illumination is achieved, but light efficiency deteriorates due to loss of light in the lower intensity wings
Solution Approach 1:
The patent transforms the Gaussian beam intensity profile into a rectangular (flat-top) profile by modifying the beam parameters through optical elements. Specifically, it uses a phase plate to alter the phase distribution of the Gaussian beam, followed by Fourier transformation optics to convert the modified phase profile into a uniform intensity distribution at the modulator plane, thereby achieving both uniform illumination and high light efficiency
Solution Approach 2:
The patent introduces intermediate optical elements (phase plate and Fourier transforming lens) between the Gaussian laser source and the modulator array. These intermediaries transform the Gaussian beam into a rectangular beam profile, enabling efficient coupling to the modulator while maintaining uniform illumination across the modulator surface
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a significantly improved light intensity profile that matches the requirements of MEMS light modulators, achieving an efficiency of over 60% in using the light emitted by laser arrays for uniform illumination, enhancing image brightness and efficiency.
Implementation Method 1
The use of a phase plate with notches to modify the Gaussian beam profile into a rectangular profile, achieved through Fourier transform relationships
Implementation Method 2
focusing the light with lenses
Data Source
AI summary
A phase plate and lens modify light beams emitted by an array of lasers to form an efficient illumination source for a MEMS light modulator array. The phase of the electric field emitted by the lasers is modified such that the after passing through a lens the beam profile at the lens focal plane has an approximately rectangular shape appropriate for illuminating a light modulator array. The phase plate may be constructed from a glass plate with rectangular notches etched in it or with rectangular ridges formed on it. Furthermore a light source, such as a laser, may be coupled to an adiabatically tapered optical waveguide in which a phase adjusting block is introduced in analogy to notches in a bulk phase plate. Phase modified light beams output from the waveguide system have similar focusing properties to those passing through a bulk phase plate.