Justin Albert Univ. of Victoria Sept. 12, 2006 : A Tunable Laser in Space Dark Energy Atmospheric Physics National Security

Limitations on our Knowledge of Dark Energy  Calibration of, and corrections to, distance measurements are a significant source of uncertainty in measured cosmological parameters.  Unless we improve calibration standards (for flux as a function of color) to < 1%, this will be a limiting systematic for upcoming projects … : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 2 Universe is ACCELERATING Best fit

Understanding the Acceleration of the Universe … and others Launch date ~2013 First data ~2011 First data this year ! : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 3

Systematic Uncertainties are the Key  Minimizing uncertainties on these cosmological parameters is largely a matter of keeping systematic uncertainties at a minimum (especially flux as a function of redshift). From Kim, Linder, Miquel, & Mostek (MNRAS, 2004): : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 4

The Same Applies to Weak Gravitational Lensing  The 3 main techniques for measuring the cosmological parameters: using type Ia supernovae (“standard candles”: measure luminosity and redshift), weak gravitational lensing (shapes of galaxies “lensed” by foreground matter, as a function of their redshift), and “baryon oscillations” (ripples are present in the distribution of galaxies, as a function of redshift). All require superb redshift (spectrophotometric) calibration. From Bernstein & Jain (ApJ, 2004): : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 5

And Atmospheric Science Applications  The CALIPSO satellite (launched on Apr. 23 of this year) uses an Nd:YAG LIDAR laser at 1064 and 532 nm to measure the properties of clouds and the atmosphere. A tunable laser (and LIDAR receiver) could provide information in a far greater range of wavelengths. : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 6

Improving Fundamental Calibration Not Easy Need to get above the ATMOSPHERE Idea: Rockets (ACCESS) Another possibility: Balloons But even after you very carefully calibrate them, stars are VARIABLE (majority on the > 1% scale). Wouldn’t it be nice to just have a (man-made) source up there … ? : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 7

Using a Tunable Laser on the Ground : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 8 âUse tunable laser to calibrate telescope optical throughput (Stubbs & Tonry):

A Tunable Laser in Space 1)Would allow atmospheric calibration for all major ground- based observatories (without any worries of stellar variability). 2)A monochromatic source that covers the entire wavelength range (250 to 2500 nm) -- avoids worries about differences between stars and galaxies. 3)Would provide an always-available fundamental spectrophotometric standard source for space-based observatories (e.g. SNAP). 4)Minimizes calibration transfers; precision is limited essentially only by radiometer uncertainty (only 0.01% !!) 5)Cost could be reduced by placing on a satellite needed anyway (e.g. GPS-III [upgrade to GPS], TSAT?, …). 6)The defense uses of a tunable laser in space …. : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 9

Defense Applications …  Target illumination, as well as space communication. Variable wavelength (more difficult to detect, or to develop contermeasures) : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 10

Tunable laser  Just purchased Opotek Vibrant LD 355 II : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 11

Toward a Space-Qualified Tunable Laser …  The CALIPSO satellite uses an Nd:YAG laser from Fibertek Inc. that clearly is space- qualified.  Such a laser could potentially be used as a pump laser for an OPO (which would then itself need to be space- qualified).  Eli Margalith (president, Opotek Inc., Carlsbad, CA) has started to work on requirements for a space-qualified OPO. Together we will be developing a space-qualified diode-pumped OPO for laboratory tests (stability, durability, radiation hardness) over the next years. : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 12

13 Click to edit Master text styles –Second level Third level –Fourth level »Fifth level 13 OPOTEK Inc. Diode-Pumped OPO system 300 Hz, 1.8Watt Pumped by Brightlite by JMAR : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 13

Measuring the Flux (Radiometry) âLASP (Laboratory for Atmospheric and Space Physics, at UC Boulder) has produced and flown space-qualified radiometers (for solar irradiance measurement) that achieve better than 200 ppm in (laser) flux measurement (and better than 10 ppm/yr stability) : âUse as a laser radiometer. : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 14

Several Relatively Convenenient Platforms on Timescale : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 15

To Do: Tunable Laser and Diode Studies 1)Radiation Tests: Survivability/Degradation at km. TRIUMF (Canada) irradiation facility. 2)Characterize beam divergence. Beam expander optics. 3)Explore options for eliminating moving parts (or momentum-balance when absolutely necessary), reducing cooling power. 4)Electronics / power source requirements. 5)4  -radiating source, etc. : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 16

Collaboration Started and Growing : A Tunable Laser in Space 9/12/2006 : A Tunable Laser in Space J. Albert 17