Optical scanning and imaging systems based on dual pulsed laser systems

• US 8,237,122 B2
• Filed: 02/17/2012
• Issued: 08/07/2012
• Est. Priority Date: 03/06/2009
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Fermann, Martin E., Hartl, Ingmar
• Primary Examiner(s): Porta, David
• Assistant Examiner(s): Taningco, Marcus
• Application Number:
  US13/399,392
• Publication Number:
  US 20120145902A1
• Time in Patent Office: 172 Days
• Field of Search: 250/341.1
• US Class Current: 250/341.1
• CPC Class Codes: G01B 9/02001 characterised by controlling or generating intrinsic radiation properties
• CPC Class Codes: G01N 2021/317 Special constructive features
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G02B 6/02304 Core having lower refractive index than cladding, e.g. air filled, hollow core
• CPC Class Codes: H01S 3/0675 Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/08054 Passive cavity elements acting on the polarization, e.g. a polarizer for branching or walk-off compensation quarter-wave plates in a Q-switch laser H01S3/1124, H01S3/115
• CPC Class Codes: H01S 3/10046 Pulse repetition rate control H01S3/11 takes precedence
• CPC Class Codes: H01S 3/1067 using pressure or deformation
• CPC Class Codes: H01S 3/1068 using an acousto-optical device
• CPC Class Codes: H01S 3/1115 using intracavity saturable absorbers
• CPC Class Codes: H01S 3/13 Stabilisation of laser output parameters, e.g. frequency or amplitude
• CPC Class Codes: H01S 3/1307 Stabilisation of the phase
• CPC Class Codes: H01S 3/1392 by using a passive reference, e.g. absorption cell H01S3/1396, H01S3/1398 take precedence
• CPC Class Codes: H01S 3/1394 by using an active reference, e.g. second laser, klystron or other standard frequency source
• CPC Class Codes: H01S 3/2383 Parallel arrangements

Abstract

The invention relates to scanning pulsed laser systems for optical imaging. Coherent dual scanning laser systems (CDSL) are disclosed and some applications thereof. Various alternatives for implementation are illustrated, including highly integrated configurations. In at least one embodiment a coherent dual scanning laser system (CDSL) includes two passively modelocked fiber oscillators. The oscillators are configured to operate at slightly different repetition rates, such that a difference δf_r in repetition rates is small compared to the values f_r1 and f_r2 of the repetition rates of the oscillators. The CDSL system also includes a non-linear frequency conversion section optically connected to each oscillator. The section includes a non-linear optical element generating a frequency converted spectral output having a spectral bandwidth and a frequency comb comprising harmonics of the oscillator repetition rates. A CDSL may be arranged in an imaging system for one or more of optical imaging, microscopy, micro-spectroscopy and/or THz imaging.

Claims

1. A system for imaging in the THz spectral range comprising:

a coherent dual scanning laser system (CDSL) comprising two passively modelocked fiber oscillators, said modelocked oscillators configured to operate at slightly different repetition rates, such that a difference δ

fr in repetition rates is small compared to the values fr1 and fr2 of the repetition rates of said oscillators;

a feedback system for stabilizing the difference in the repetition rates of the two oscillators, wherein information generated by said feedback system is used to generate a frequency grid in the RF domain that has a 1;

1 correspondence to a frequency grid in the THz domain, and allowing an RF frequency to be scale to a THz frequency;

a material emitting THz radiation in response to an output of said CDSL; and

a detector responsive to said THz radiation.

2. A system for imaging in the THz spectral range comprising:

a coherent dual scanning laser system (CDSL) comprising two passively modelocked fiber oscillators, said modelocked oscillators configured to operate at slightly different repetition rates, such that a difference δ

fr in repetition rates is small compared to the values fr1 and fr2 of the repetition rates of said oscillators;

a monitoring system for monitoring the difference in the repetition rates of the two oscillators, wherein information generated by said monitoring system is used to generate a frequency grid in the RF domain that has a 1;

1 correspondence to a frequency grid in the THz domain, and allowing an RF frequency to be scale to a THz frequency;

a material emitting THz radiation in response to an output of said CDSL; and

a detector responsive to said THz radiation.