Direct Optical Image Projector Using Spatial Light Modulator
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Solution Overview
Problem
Conventional tilting-mirror image projectors are inefficient as they reflect part of the illumination light away from the viewing screen, resulting in lost light and inefficient image projection.
Innovation Solution
The use of a reconfigurable spatial light modulator, a coherent light source, and a transmission filter to form a coherent light wavefront with spatially varying amplitude and phase modulations, focusing the light to project images efficiently onto a viewing screen by redistributing light rather than reflecting it away.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a tilting-mirror array is used to reflect light, then image projection is achieved, but light efficiency deteriorates because part of the illumination light is reflected away from the viewing screen
Solution Approach 1:
Instead of using mirrors to reflect light away from the viewing screen, the patent inverts the approach by using a spatial light modulator to redirect light onto the viewing screen. The SLM modulates the incident light wavefront to construct a coherent light wavefront that is focused onto the viewing screen, ensuring that light is redistributed onto the screen rather than reflected away, thereby eliminating light loss while maintaining image projection capability
Solution Approach 2:
The patent changes the fundamental parameter of light manipulation from reflection (tilting mirrors) to wavefront modulation (spatial light modulator). By controlling the amplitude and phase of the incident light wavefront through the SLM, the system transforms the light into a coherent wavefront that is focused onto the viewing screen, improving light efficiency while achieving the same image projection function
2Ease of operation
If incoherent light sources are used with tilting mirrors, then simple image projection is achieved, but image quality deteriorates due to loss of light and inefficiency
Solution Approach 1:
The patent changes the light source parameter from incoherent to coherent light. By using a coherent light source and a spatial light modulator to control the wavefront, the system achieves superior image quality through constructive interference and focused light distribution. The coherent light enables precise control over the light wavefront, resulting in higher image quality while the SLM maintains operational simplicity through digital control
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 enhances light utilization and image projection efficiency by ensuring that light is redirected onto the viewing screen, improving the quality and clarity of projected images.
Implementation Method 1
The reconfigurable spatial light modulator is capable of producing spatially varying amplitude and/or phase modulations of an incident light wavefront
Implementation Method 2
Various embodiments provide image projectors that are based on coherent light sources
Implementation Method 3
The apparatus may include a lens system configured to cause the outgoing light beam to focus such that the light pattern is able to form where the outgoing beam is focused
Implementation Method 4
focusing a light beam such that the outgoing light beam can form a diffractive light pattern that is approximately a Fourier transform of the modulated wavefront
Implementation Method 5
The transmission filter is configured to spatially filter a light pattern formed by the outgoing light beam and to selectively transmit light from substantially only one diffractive order of the light pattern
Implementation Method 6
each mirror reflects part of the illumination light in a manner that depends on the mirror's orientation. The MEMS actuator tilts the corresponding mirror to reflect illumination light either towards a viewing screen or away from the viewing screen
Implementation Method 7
The light source may include a plurality of coherent sources, wherein each coherent source emits light of a different color than the remaining of the coherent sources. The light source may illuminate the mirrors with a time division color-multiplexed light beam
Data Source
AI summary
An apparatus includes a reconfigurable spatial light modulator, a light source, and a transmission filter. The reconfigurable spatial light modulator is capable of producing spatially varying amplitude and/or phase modulations of an incident light wavefront. The light source is configured to direct an illumination light beam towards the reconfigurable spatial light modulator such that the modulator produces a modulated outgoing light beam there from. The transmission filter is configured to spatially filter a light pattern formed by the outgoing light beam and to selectively transmit light from substantially only one diffractive order of the light pattern.