Spatial Light Modulation for Axial Focus Shifting in Telecentric Optics
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Solution Overview
Problem
The existing light irradiation apparatus requires complex structure adjustments to vary the irradiation position of modulated light in the optical axis direction due to a small depth of focus, necessitating movement of the telecentric optical system and the irradiation object.
Innovation Solution
A light irradiation apparatus with a spatial light modulator displaying a Fresnel type kinoform, allowing the irradiation position to be changed by modifying the kinoform on the phase modulation plane without moving the optical system, utilizing a Kepler type afocal optical system with a convex front lens and a convex or concave rear lens to adjust the light condensing point position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the modulated light is focused at a light condensing point through a telecentric optical system, then the intensity distribution is transferred to the target plane, but the variable range of the irradiation position in the optical axis direction is limited to the depth of focus which is considerably small
Solution Approach 1:
The patent replaces the mechanical movement system (moving the telecentric optical system or irradiation object) with an optical phase modulation system. By displaying different Fresnel lens patterns on the spatial light modulator, the irradiation position in the optical axis direction can be varied without any mechanical movement, thus resolving the contradiction between precision and adaptability.
Solution Approach 2:
The patent changes the optical parameters by modulating the phase of light using different Fresnel lens patterns displayed on the spatial light modulator. By changing the phase distribution parameters through pattern switching, the irradiation position variable range is extended beyond the depth of focus limitation while maintaining intensity distribution precision.
2Adaptability or versatility
If the telecentric optical system and irradiation object are moved in the optical axis direction to change the irradiation position, then the irradiation position variable range is increased, but the device structure becomes complicated
Solution Approach 1:
The patent eliminates the need for mechanical movement components by using optical phase modulation. The spatial light modulator displays different Fresnel lens patterns to achieve irradiation position variation, completely replacing the mechanical movement system and thereby reducing device complexity while maintaining or expanding the irradiation position variable range.
Solution Approach 2:
The patent uses computer-generated holograms (Fresnel lens patterns) to create virtual optical elements that can be dynamically changed. Instead of physically moving components, the system creates optical copies or equivalents through phase modulation patterns, simplifying the overall device structure.
3Ease of operation
If a Fresnel type kinoform is displayed on the phase modulation plane, then the irradiation position can be easily changed in the optical axis direction, but the zeroth-order light component effects must be managed
Solution Approach 1:
The patent extracts or separates the zeroth-order light component from the modulated light using optical filters or spatial separation techniques. By removing this harmful component while retaining the useful Fresnel lens pattern effects, the system achieves easy irradiation position adjustment without the detrimental zeroth-order light effects.
Solution Approach 2:
The patent converts the zeroth-order light component, which is initially harmful, into a useful element by using it as a reference beam or by its diffraction effects to enhance the overall optical field distribution, thereby transforming the harmful factor into a beneficial one while maintaining ease of operation.
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
Enables easy adjustment of the irradiation position and numerical aperture of modulated light in the optical axis direction, simplifying the device configuration and increasing the variable range of the irradiation position, while maintaining high intensity uniformity and reducing zeroth-order light component effects.
Implementation Method 1
a spatial light modulator (20) which generates modulated light L2 by modulating the readout light L1 in phase
Implementation Method 2
a Fresnel type kinoform is displayed on the phase modulation plane 20a
Implementation Method 3
the optical system 30A has a front lens 31 and a rear lens 32... the modulated light L2 is condensed to form a light condensing point
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A light irradiation device 1A is an apparatus for irradiating an irradiation object B, and includes a light source 10 outputting readout light L1, a spatial light modulator 20 modulating the readout light L1 in phase to output modulated light L2, and a both-sided telecentric optical system 30A including a lens 31 optically coupled to a phase modulation plane 20a of the spatial light modulator 20 and a lens 32 optically coupled between the lens 31 and the irradiation object B, and optically coupling the phase modulation plane 20a and the irradiation object B. An optical distance between the phase modulation plane 20a and the lens 31 is substantially equal to a focal length of the lens 31. The spatial light modulator 20 displays a Fresnel type kinoform on the phase modulation plane 20a. A light irradiation apparatus capable of easily changing the irradiation position of modulated light in the optical axis direction is thereby realized.