Broadly Tunable Optical Parametric Oscillator for Microscopy
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Solution Overview
Problem
Current tunable ultrafast laser systems for multi-photon microscopy have limited depth of penetration due to material dispersion and optical losses at longer wavelengths, requiring a broader tuning range from 680nm to 1400nm with fully automated dispersion compensation and a single output port.
Innovation Solution
A laser system comprising a subpicosecond pump source and a Type I or Type II optical parametric oscillator with a polarization selector or delay line to produce a singly resonant optical parametric oscillator, enabling continuous tunability from 650nm to 1400nm with dispersion compensation for ultrafast pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a Ti:sapphire laser is used to provide broad tunability from 680nm to 1080nm, then the tuning range is improved, but the depth of penetration into biological samples is limited due to scattering and optical losses at longer wavelengths
Solution Approach 1:
The patent extends the operational wavelength range by changing the resonator parameters and optical components to support wavelengths from 680nm to 1400nm. This includes using broadband high-reflectivity mirrors with enhanced reflectivity at longer wavelengths, adjusting cavity length, and modifying dispersion compensation elements to maintain laser oscillation and pulse quality across the extended range.
2Length of moving object
If the wavelength is extended beyond 1080nm to improve depth of penetration, then the penetration depth is improved, but the average power and pulse energy decrease due to increased optical losses
Solution Approach 1:
The patent converts the potentially harmful effect of increased optical losses at longer wavelengths into a benefit by designing a resonator that operates efficiently in this regime. The broadband high-reflectivity mirrors and optimized cavity design transform the wavelength extension from a loss-inducing modification into a feature that enables deeper penetration while maintaining useful power levels through enhanced coupling and reduced parasitic losses.
Solution Approach 2:
The patent employs dynamic dispersion compensation using movable prisms or gratings that can be adjusted to optimize pulse compression and maintain transform-limited pulses across the extended wavelength range. This dynamic adjustment allows the system to adapt to changing dispersion characteristics as the wavelength is tuned from 680nm to 1400nm, preserving pulse quality and peak power.
3Adaptability or versatility
If a singly resonant optical parametric oscillator is used to extend tuning to 1400nm, then the continuous tunability is improved, but the device complexity increases due to additional components like polarization selectors or delay lines
Solution Approach 1:
The patent segments the wavelength tuning range into different operational regimes that can be accessed by adjusting the pump laser wavelength and OPO cavity parameters. By dividing the 680nm-1400nm range into manageable segments with optimized settings, the system achieves continuous tunability without requiring a complete redesign for each wavelength, thereby controlling complexity while maintaining versatility.
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 system achieves broad tunability and high average power with 100fs pulses, enhancing depth of penetration and flexibility in multi-photon microscopy applications by eliminating tuning gaps and material dispersion issues.
Implementation Method 1
at least one type II optical parametric oscillator in optical communication with the pump source and configured to generate a single pulsed optical signal having a wavelength continuously tunable from about 650nm to about 1400nm
Implementation Method 2
The system achieves broad tunability and high average power with 100fs pulses, enhancing depth of penetration and flexibility in multi-photon microscopy applications by eliminating tuning gaps and material dispersion issues
Data Source
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AI summary
A novel broadly tunable optical parametric oscillator is described for use in numerous applications including multi-photon microscopy. The optical parametric oscillator includes at least one sub-picosecond laser pump source configured to output a pump signal having a wavelength of about 650nm or less and at least one type II optical parametric oscillator in optical communication with the pump source and configured to generate a single widely tunable pulsed optical signal. In one application, an optical system is in optical communication with the optical parametric oscillator and configured to direct at least a portion of the optical signal to a specimen, and at least one analyzing device is configured to receive a signal from the specimen in response to the optical signal.