Using Machine Vision Cameras for Solar Imaging Dr Stuart Green
Hubble Ultra-deep Field Image Estimated 100 billion galaxies in the observable universe
Estimated 200-400 billion stars in our own galaxy Milky Way
The Sun Only one star that we can study up close and even that s 150 million km away!
Contents Introduction Telescopes for solar imaging Factors impacting image quality o o Matching camera to scope - Camera characteristics Coping with variable seeing - atmospheric effects Image capture and processing Summing up Future needs
Pioneers in Solar Astronomy Sunspot drawing- Galileo Galilei 1612 Solar Eclipse- Warren De la Rue 1860
Early Space Observations of The Sun http://history.nasa.gov/sp-402/contents.htm Skylab- 1973-1979
Current Space Observations of The Sun SDO
Current Space Observations of The Sun- International Space Station Sun Monitoring on the External Payload Facility of Columbus (Solar) - Solar Spectral Irradiance Tim Peake
The Sun white light (continuum) Richard Bailey Christian Viladrich
The Sun in hydrogen alpha light at 656.3nm
Solar Prominences in hydrogen alpha light at 656.3nm
Closer view of active regions (sunspots)
The Sun in Calcium-K light at 393.4nm Mark Townley
White light photosphere Chromosphere- 2,100km thick region above Photosphere
Example Solar Telescopes and filters
Lunt 60THa Double Stacked
Factors Impacting Image Quality Lens quality Aperture Focal length Filter tuning Telescope Characteristics Atmospheric Characteristics Camera Sensor Characteristics Sensor size Pixel size Number of Pixels Shutter type Quantum efficiency Dynamic range Noise/SNR Frame rate Output Sharpness Brightness Contrast Clarity Stability (seeing)
Post Processing At Scope Target, Focus, Tune Tracking Mount Machine Vision Camera Image Acquisition Few Seconds AVI Image Stacking Produces best image from many Image Enhancement Deconvolution/Sharpening Image Refinement Adding Colour
At Scope Matching Camera to Telescope Target, Focus, Track Tracking Mount Machine Vision Camera Image Acquisition Few Seconds AVI Telescope Characteristics Camera Characteristics Type of image required
Telescope Resolution R= 1.22 λ D 0 R= radius of disc (radians) λ= Wavelength of light D 0 = Diameter of objective lens a) Small objective lens b) Medium objective lens c) Large objective lens d) Resolvable image e) Non-resolvable image Adapted from Zeiss Microscopy Online Campus
Telescope Resolution
Telescope Resolution Angular resolution Small D 0 Large D 0
Telescope Resolution 50km Resolution, 0.07 arc Second 1.6 m (63 in) clear aperture open frame, off-axis Gregorian telescope Big Bear telescope- California
Matching Scope and Camera
Camera Characteristics
Cameras Commonly used.. Sensor Type Pixels (MPix) Pixel Size Frame rate IDS µeye IDS 3370 CMOS 4.2 5.5 90 Basler aca1920-155 IMX174 CMOS 2.3 5.86 150 DMK41 ICX205AL CCD 1.2 4.65 15 DMK51 ICX274AL CCD 1.9 4.4 12 PGR Blackfly IMX249 CMOS 2.3 5.86 41 PGR Chameleon 3 ICX445 CCD 1.3 3.75 18 PGR Flea 3 ICX445 CCD 1.3 3.75 31 PGR Flea 3 (Rolling) IMX036 CMOS 3.2 2.5 60 PGR Grasshopper 3 ICX694 CCD 6 4.54 13 PGR Grasshopper 3 ICX808 CCD 4.1 3.1 18 PGR Grasshopper 3 ICX674 CCD 2.8 4.54 26 PGR Grasshopper 3 CMV4000-3E5 CMOS 4.1 5.5 90 ZWO ASI120MM-S MT9M034 CMOS 1.2 3.75 70 ZWO174 IMX174 CMOS 2.3 5.86 128
Sampling Under sampling
Sampling Telecentric lens increases image scale on sensor
Telescope Resolution Mercury D~12 arcsec 60mm Lunt THa Scope + 1.5x Barlow with Basler aca1920-155um (5.86µm Pixels) Airy Disc 5.45 arcsec
Image Scale Image scale for selected commercial solar telescopes at native focal length
Mosaic
Atmospherics- Seeing Pedro Re
Atmospherics- Seeing
Atmospherics- Seeing
Atmospherics- Seeing
Camera Characteristics
Camera Characteristics Rolling Shutter Global Shutter
Camera Characteristics Faint solar prominence Sony IMX174 Sensor- Dynamic range and sensitivity to capture short duration images of disk and proms together.
Camera Characteristics CMOS- Newton s Rings Tilt Adapter
Post Processing AVI Image Stacking Produces best image from many Image Enhancement Deconvolution/Sharpening Image Refinement Adding Colour
Image Stacking Single frame from AVI 10ms (1/100s)- some blurring due to atmospheric turbulence Few hundred images captured as AVI or SER file
Image Stacking
Image Stacking
Image Stacking Single frame from AVI Stacked image
Image Deconvolution
Image Deconvolution
Adding Colour Alexandra Hart
Adding Colour
Summing up The Sun is easily accessible to amateur astronomers. Interesting and exciting images can be captured using modest imaging equipment, including Machine Vision cameras. Best results achieved by optimising telescope and camera capabilities- frame rate, pixel size and numbers, dynamic range are all important factors Modern image processing software (much of it free) enables high quality images to be created, correcting for atmospherics, and improving apparent resolution.
Future CMOS without Newton Rings More speed More sensitivity Tuneable wavelength narrow band camera!
Thank You http://solarchatforum.com