# Presentation: 501056

## X-ray Interferometer Mirror Module ISAL Study

- Pre-work Overview

## Science Team

- Webster Cash - University of Colorado
- 303-492-4056
- Ann Shipley -	University of Colorado
- 303-492-1875
- Keith Gendreau - NASA/GSFC Code 662
- 6-6188

## Science Driver for MAXIM

- Current best estimates for the size of the event horizon of a blackhole:  a few microarcseconds
- Variability and spectral data describe an x-ray bright region near the event horizon.
- Baselines at 1-10Å are a factor of of 1000 shorter than at 1000-10000Å
- The *MAXIM *mission will have  resolution of 0.1 as.
- Resolve the event horizon
- Study physics and dynamics of inner accretion region near event horizon
- For Scientific and Technical context, we are exploring  *MAXIM Pathfinder  *mission concepts.
- Discover where AGN Jets take off
- Study Stellar Coronae

**http://maxim.gsfc.nasa.gov**

## Science Driver for MAXIM

## A Simple X-ray Interferometer

- Flats

- Beams Cross

- Detector

- s

- L

- d

- Fringe Spacing:

-  Grazing Incidence softens tolerances by ~2 orders of magnitude. Optics that are diffraction limited for normal incidence UV  is diffraction limited for grazing incidence X-rays.
-  Use “simple” optics to keep diffraction limit.
-  Demonstrated in lab at ~10 Angstroms (1.25 keV).  W. Cash *et al,* Nature 407  14 September 2000
-  Demonstrated at GSFC with 23.6 Angstroms 27September 2002

## How to implement the simple X-ray Interferometer

- Full MAXIM- the black hole imager

- Nanometer formation flying
- Primaries must point to milliarcseconds

**Pre FY02 Baseline Mirror Grouping**

**Improved Mirror Grouping**

- Group and package Primary and Secondary Mirrors as “Periscope” Pairs

- “Easy” Formation Flying (microns)
- All s/c  act like  thin lenses- Higher Robustness
- Possibility to introduce phase control within one space craft- an x-ray delay line- More Flexibility
- Offers more optimal UV-Plane coverage- Less dependence on Detector Energy Resolution
- Each Module, self contained- Lower Risk.

**A scalable MAXIM concept.**

## The Periscope Module- the subject of this ISAL study

- The Periscope module  is a convenient place to break out two radically different tolerance levels
- Nm and ~mas relative positioning and pointing within the modules
- Micron and arcsecond module to module alignment
- Some further study makes our Periscope mirror “pairs” into mirror “quads”
- 4 bounce optical situation required to maintain coarse module to module alignment

## MAXIM Pathfinder IMDC Study May 2002

- Launch

- Transfer Stage

- Science Phase #1
- Low Resolution (100 as)

- 200 km

- Science Phase #2
- High Resolution
- (100 nas)

- 1 km

- 20,000 km

## Goals for this Study

- How do you make these light weight mirrors so they are flat to better than /200?
- How do you hold these mirrors with actuators to move them by ~nm over microns of range?  Which Actuators and controlling electronics?  Do you put actuators on all the mirrors?
- How does the structure provide an environment suitable to maintain the mirror figure and stability?
- Do we need internal metrology?  How to implement?
- How do we register one module’s mirror surfaces to another modules mirror surfaces at the micron level?
- How to mass produce these?  By how much does this save costs?
- What would the alignment procedures be?
- Trade Studies- three different mirror module sizes,..
- We need the usual IMDC cost/mass/power inputs.  Drawings.

## Periscope Configuration

- Detector

- Periscope Modules

## Mirror Parameters

- TBD

- Active area is  30 cm long by either 2,10 or 30 cm wide-  so **THREE different types of mirror modules for a trade study**
- Surface figure requirement: /200 rms (at 633nm)
- Mirror mass must be minimized

- 2,10, and 30 cm
- TRADE STUDY

- Mirror surface

## Sketch of a module

- Thermal Precolimator?

- Door/Shutter

- Thermal Precolimator?

- Alignment window?

- X-rays

## More on module tolerance later by Ann Shipley

- See PPT presentation by Ann and other supporting material.

## 

- 

- tan

- sin

- *cos2

- 

- +2=180 degrees

- +=180=2

- 

- OPD=  (1-cos2)= 2sin2

## The CCD will produce several images at different wavelengths at the same time.

- The total bandpass of the CCD will be from 50 angstroms to 1.5 angstroms.
- Over this bandpass there will be several “colors” due to the energy resolution of the CCD.
- At an energy E (in eV) the energy resolution will be dE=1.9*SQRT(E) in eV.
- So, one color will be centered at an energy E with a energy width of dE.
- Convert this “color” into units of lambda and d_lambda.... Lambda and delta lambda will determine the “ultimate visibility” you could get for that color image. Lambda will also give you the fringe period .
- You will have different fringe periods and ultimate visibilities  for each color.
- A common term will also affect all the visibilities of all the colors- and that term is the OPD between the channels- we are trying to optimize this.
- For each color, we will “fit” a curve  of event probability (a function of lambda, d lambda, and the OPD) through a bunch of points.  One color will not look very exciting.
- The fit will actually be a joint fit of ALL the colors for the common parameter of OPD.....