# Presentation: 208247

## CORSAIRCalibrated Observations of Radiance Spectra in the Far-Infrared 

**Marty Mlynczak**
***NASA Langley Research Center***

## The CORSAIR Team

**NASA Langley**
- Marty Mlynczak, PI
- Sharon Graves, PM
- Richard Cageao
- Dave Johnson
- Nurul Abedin
- Dave Kratz
- Xu Liu
**ITT**
- David Jordan
**Raytheon Vision Systems**
- Jinxue Wang
**Space Dynamics Laboratory**
- Gail Bingham
- Harri Latvakoski
**NIST**
- Simon Kaplan
**JPL**
- Kevin Bowman

## Far-IR Sensors and Science at Langley

- _Timeline of Projects_
- FIRST Instrument
- IIP 2001
- INFLAME Instruments
- IIP 2004
- NRC White Paper
- Decadal Survey Call 2005
- CERES/AIRS
- EOS recompetion, 2005
- FIDTAP
- ATI 2006
- FORGE
- Radiation Sciences Program 2006
- CORSAIR
- IIP 2007

## CORSAIR -- Outline

**Background on the Far-Infrared**
- Definitions and Science
- The FIRST Project
**Elements of the CORSAIR IIP Project**
- Detectors
- Blackbody Radiance Standards
- Broad Bandpass Beamsplitters
**Some Thoughts on The Way Forward**
- Instrument Modeling
- Calibration Demonstration Unit
- Atmospheric Observations

## Earth’s Infrared Radiance Spectrum

**Earth’s Infrared Radiance Spectrum**

## Compelling Science of the Far-Infrared

- FIRST - Science Flights 6/2005; 9/2006
- Demonstrated far-IR interferometer technologies

**Measurement of Cirrus Opt. Depth**

**Collins and Mlynczak, 2001**

** ****Mlynczak et al., 1998**

**Yang et al., 2003**

## FIRST: Technology and Science

- First complete infrared spectrum of Earth

- FIRST Focal Plane Array

- Technology Development through IIP
- Partners: SDL; SAO

- Effects of middle troposphere temperature

**Mlynczak et al., 2006**

**Harries et al., 2008**

## The CORSAIR Project

## CORSAIR - Overview

**FIRST demonstrated:**
**High throughput FTS (0.47 cm****2**** sr)**
**Far-IR beamsplitter**
**Cryogenic Focal Plane Design **
**CLARREO Requires:**
**Far-IR detectors operating above liquid helium temperatures**
**Far-IR blackbodies traceable to SI standards**
**Broad bandpass beamsplitters (5 to 50 ********m)**
**CORSAIR IIP to demonstrate these technologies at TRL-6 **

## CORSAIR - Major Technology Elements

- Passively Cooled Detectors (Raytheon Vision Systems)
- Antenna Coupled Terahertz Devices
- Potential for 100 to 1000 times more sensitive (D*) than pyroelectric
- Substantial prior DARPA and Homeland Security investment
- Detectors evaluated in Year 3 in FIRST @ Langley
- SI Traceable Blackbodies in Far-IR (SDL; NIST)
- Flight prototype blackbody w/ well-characterized emissivity
- On-orbit, SI-traceable temperature measurement for blackbody
- On-orbit emissivity monitor in far-IR
- Broad Bandpass Beamsplitters (ITT)
- Cover 5 to 50 m region in 1 beamsplitter
- Potentially enables 1 instrument to cover CLARREO range

## Antenna-Coupled Technology

- Far-IR Energy Couples to Antenna Optimized for Specific LW Band & Bandwidth
- Antenna Passes Current to the Detector (Diode)
- Detector Connects to ROIC through Conducting Leads
- ROIC Reads Out Resistance for Each Pixel &  Multiplexes Output
- D* above 1e+10 cm sqrt(Hz)/W predicted

**LW Pixel with MicroAntenna**

**Antenna Captures LW Radiation **
**   ****Energy Coupled to Detector**

***LW Power Flows from Antenna to Detector***

**Detector Element**

**Bowtie Antenna**

**Connections to Readout Circuitry**

## Requirements and Project Milestones

**Spectral Range: ****	****15 to 50 ********m**
**Specific Detectivity: ****	****1e + 10 cm sqrt(Hz)/W**
**Bandwidth: ****	****Greater than 3:1**
**NEP: ****	****Less than 2e-11 W/sqrt(Hz)**
**Sampling Frequency: ****	****2 kilohertz**
**Operating Temperature: ****	****285 to 295 Kelvin**
**Dark Current Shot Noise: ****	****4 picoamperes/sqrt(Hz)**
**Critical  Design Review: ****	****	****March 2009**
**Detector Lot 1 Fab. and Test: ****	****August 2009 ****	****TRL 4**
**Detector Lot 2 Fab. and Test: ****	****September 2010 ****	****TRL 5**
**Detectors Delivered to Langley: ****	****October 2010**
**Testing in FIRST completed: ****	****	****August 2011 ****	**** ****TRL 6**

## CORSAIR Far-IR Blackbodies

- No SI-traceable standards currently exist for Far-IR
- SDL, NIST, and Langley will work to develop SI-traceable BB sources for the Far-IR
- Approach
- Install phase change cells on FIRST LW Calibration Source (LWIRCS)
- NIST/SI certify LWIRCS in NIST LBIR facility
- Develop CLARREO flight demo Far-IR blackbody
- Include Far-IR emissivity monitor
- Calibrate against LWIRCS
- Flight demo Blackbody to be delivered to Langley
- SI traceable temperature via phase change cells and calibration against LWIRCS
- Emissivity monitoring to better than 3 parts in 10,000

## Far-Infrared Spectrum in Brightness  Temperature

## Effects of Emissivity Error on Far-IR Calibration

**Emissivity must be known better than 3 parts in 10,000**

- 0 = 0.9999

## Effects of Emissivity Error on Far-IR Calibration

- 0 = 0.9999

**Emissivity must be known better than 3 parts in 10,000**

## FIRST LWIRCS

**LWIRCS to be calibrated at the NIST LBIR facility**
**Will be SI-traceable radiance standard upon completion**

## Project Requirements and Milestones

**SI-traceable LWIRCS (0.1 K, 3-********) **
**Design and build flight demo blackbody**
**Incorporate emissivity monitor to 3 parts in 10,000**
**Spectral range of BB: 15 to 50 ********m minimum**
**LWIRCS calibration at NIST LBIR:****	****April 2009****	****TRL 6**
**(SI-traceable far-IR calibration standard)**
**Flight demo BB Design Review****	****Dec. 2009**
**Flight demo BB development:****	****July 2010****	****TRL 5**
**Flight demo BB testing and eval:****	****July 2011****	****TRL 6**
**Delivery of far-IR BB to Langley: ****	****August 2011**
**(SI-traceable, PCM cells, emissivity monitor)**

## CORSAIR Broad Bandpass Beamsplitters

- CLARREO Requirement in Decadal Survey
- Interferometer covering 5 to 50 m
- Presents challenges in
- Detectors
- Optical coatings
- Beamsplitters
- CORSAIR will develop and demonstrate a single beamsplitter capable of passing the entire CLARREO range with minimal absorption and maximum efficiency

## Project Requirements and Milestones

- Wavelength Range: 	5 to 50 m
- R-T Product: 	4[R] [T] = 1.0, 5 to 50 m
- Beamsplitter Design		3/2009
- Computer Model Development	6/2009
- Design Review		7/2009
- Fabricate first beamsplitter	9/2009 	TRL 4
- Develop Test Setups		12/2009
- Fabricate Beamsplitters	4/2010
- Test Beamsplitters		8/2010  	TRL 5
- Beamsplitters Thermal cycling	1/2011
- Comprehensive Test and Evaluation	6/2011 	TRL 6
- Delivery of Beamsplitters to Langley	9/2011

## The Way Forward

## Model, Build, Measure. Repeat.

**There is no equivalent atmospheric measurement heritage in the far-IR as there is in the mid-IR (e.g, S-HIS; NAST-I; AIRS, IASI, etc.)**
**Achieving Far-IR accuracy for CLARREO will require us to do the following in addition to developing component technologies:**
**1. Develop detailed instrument model as part of instrument design process**
**2. Build a “Calibration Demonstration Unit” to show SI-traceability of system and validity of instrument model**
**3. Conduct “viable” atmospheric measurements and intercomparisons amongst various extant instruments **
**There are 4 Far-IR instruments worldwide: **
**FIRST****	****TAFTS****	****    REFIR       AERI-ER**
**Must continue to measure the far-IR spectrum and validate knowledge of calibration in all respects**
**Example: RHUBC/FORGE Campaign, Atacama Desert, Chile, in 2009 **

## RHUBC/FORGE Campaign Details

- RHUBC-II/FORGE
- 1 Aug - 31 Oct 2009
- Cerro Toco or Chajnantor Plateau, Chile. 5.1 km altitude (17,000 feet)
- Minimum PWV: 0.1 mm (anticipated)
- Key instrumentation:
- Infrared FTS: FIRST, AERI-ER, REFIR-PAD, TAFTS(?)
- Microwave Radiometers: MP-183, RS-92, MPL, GVR
- RS-92 radiosondes

## CORSAIR Summary

- The far-IR spectrum is a frontier in climate sensing
- Substantial strides to date in achieving technologies required for routine, extended space-based far-IR observations
- CORSAIR will develop and demonstrate several remaining technologies at TRL 6 (from TRL 3)
- Antenna coupled detectors for Far-IR
- SI Traceable Blackbodies for Far-IR
- Broad bandpass beamsplitters
- IIP’s need to be complemented with on-going measurements to develop “working knowledge” of far-IR hardware and calibration

## Public Service Announcements

**Appearing in **_**Rev. Geophys**_**. imminently:**
**Harries, J., B. Carli, R. Rizzi, C. Serio, M. Mlynczak, L. Palchetti, T.Maestri, H. Brindley, and G. Masiello (2008), ****The Far-Infrared Earth****, Rev.Geophys., 46, ****doi:10.1029/2007RG000233.**
**Please see poster by Mark Muzilla et al. on some exciting new detector technology for the far-IR**