Laser Light Source Prism Vibration for Speckle Noise Reduction
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Solution Overview
Problem
Laser light source apparatuses used in projectors suffer from speckle noise due to coherent light interference, leading to non-uniform light intensity and a decrease in light utilization factor when methods that change the optical path are employed to reduce this noise.
Innovation Solution
A laser light source apparatus that includes a prism with specific optical flat faces and a vibration driving device to change the optical path length, generating a phase difference in the laser light, thereby reducing speckle noise without decreasing brightness. The prism can be a single right-angled triangle or trapezoid prism, or a compound prism with multiple components, vibrated in a direction parallel to the optical path, creating a phase difference in time and space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If methods that change the optical path are used to reduce speckle noise, then speckle noise is reduced, but the utilization factor of light decreases and brightness is reduced
Solution Approach 1:
The patent applies the dynamics principle by introducing a vibration driving device that vibrates the prism in a direction parallel to the optical path. This dynamic vibration changes the optical path length in a controlled manner, creating time-varying phase differences that reduce speckle noise while maintaining consistent light utilization and brightness, thereby resolving the contradiction between noise reduction and brightness maintenance.
Solution Approach 2:
The patent directly applies mechanical vibration by using a vibration driving device to vibrate the prism. This vibration modifies the optical path length dynamically, generating phase differences that interfere constructively and destructively to reduce speckle noise. The mechanical vibration approach allows for controlled optical path changes without the need to increase the apparent light source size, thus maintaining brightness while reducing noise.
2Object-affected harmful factors
If methods that change the optical path are used to reduce speckle noise, then speckle noise is reduced, but the light utilization factor decreases
Solution Approach 1:
The vibration-driven optical path change maintains efficient light utilization by avoiding the need to enlarge the apparent light source. The dynamic modulation of optical path length through prism vibration creates phase differences that reduce speckle noise without sacrificing light energy, thereby resolving the contradiction between noise reduction and light utilization efficiency.
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
The solution effectively reduces speckle noise on the screen by minimizing interference while maintaining the brightness of the projected image, as demonstrated by experimental results showing a significant speckle noise reduction effect with minimal impact on light intensity.
Implementation Method 1
a prism including a first optical flat face that is perpendicular to an optical path of the laser light and a second optical flat face that is not perpendicular to the optical path of the laser light
Implementation Method 2
a vibration driving device that vibrates the prism in a direction parallel to a direction where an optical path length in the prism of the laser light changes
Data Source
AI summary
A laser light source apparatus comprises a laser light source that emits laser light; a prism with one optical flat face, through which the laser light from the laser light source passes, that is perpendicular to an optical path of the laser light; and a vibration driving device that vibrates the prism to move the prism parallel to a direction in which an optical path length of the laser light in the prism changes, along a flat face located in the other optical flat face that does not intersect perpendicularly with the optical path of the laser light in the prism.