Using Machine Vision Cameras for Solar Imaging. Dr Stuart Green

Transcription

1 Using Machine Vision Cameras for Solar Imaging Dr Stuart Green

2 Hubble Ultra-deep Field Image Estimated 100 billion galaxies in the observable universe

3 Estimated billion stars in our own galaxy Milky Way

4 The Sun Only one star that we can study up close and even that s 150 million km away!

5 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

6 Pioneers in Solar Astronomy Sunspot drawing- Galileo Galilei 1612 Solar Eclipse- Warren De la Rue 1860

7 Early Space Observations of The Sun Skylab

8 Current Space Observations of The Sun SDO

9 Current Space Observations of The Sun- International Space Station Sun Monitoring on the External Payload Facility of Columbus (Solar) - Solar Spectral Irradiance Tim Peake

10 The Sun white light (continuum) Richard Bailey Christian Viladrich

11 The Sun in hydrogen alpha light at 656.3nm

12 Solar Prominences in hydrogen alpha light at 656.3nm

13 Closer view of active regions (sunspots)

14 The Sun in Calcium-K light at 393.4nm Mark Townley

15 White light photosphere Chromosphere- 2,100km thick region above Photosphere

16 Example Solar Telescopes and filters

17 Lunt 60THa Double Stacked

18 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)

19 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

20 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

21 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

22 Telescope Resolution

23 Telescope Resolution Angular resolution Small D 0 Large D 0

24 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

25 Matching Scope and Camera

26 Camera Characteristics

27 Cameras Commonly used.. Sensor Type Pixels (MPix) Pixel Size Frame rate IDS µeye IDS 3370 CMOS Basler aca IMX174 CMOS DMK41 ICX205AL CCD DMK51 ICX274AL CCD PGR Blackfly IMX249 CMOS PGR Chameleon 3 ICX445 CCD PGR Flea 3 ICX445 CCD PGR Flea 3 (Rolling) IMX036 CMOS PGR Grasshopper 3 ICX694 CCD PGR Grasshopper 3 ICX808 CCD PGR Grasshopper 3 ICX674 CCD PGR Grasshopper 3 CMV4000-3E5 CMOS ZWO ASI120MM-S MT9M034 CMOS ZWO174 IMX174 CMOS

28 Sampling Under sampling

29 Sampling Telecentric lens increases image scale on sensor

30 Telescope Resolution Mercury D~12 arcsec 60mm Lunt THa Scope + 1.5x Barlow with Basler aca um (5.86µm Pixels) Airy Disc 5.45 arcsec

31 Image Scale Image scale for selected commercial solar telescopes at native focal length

32 Mosaic

33 Atmospherics- Seeing Pedro Re

34 Atmospherics- Seeing

35 Atmospherics- Seeing

36 Atmospherics- Seeing

37 Camera Characteristics

38 Camera Characteristics Rolling Shutter Global Shutter

39 Camera Characteristics Faint solar prominence Sony IMX174 Sensor- Dynamic range and sensitivity to capture short duration images of disk and proms together.

40 Camera Characteristics CMOS- Newton s Rings Tilt Adapter

41 Post Processing AVI Image Stacking Produces best image from many Image Enhancement Deconvolution/Sharpening Image Refinement Adding Colour

42 Image Stacking Single frame from AVI 10ms (1/100s)- some blurring due to atmospheric turbulence Few hundred images captured as AVI or SER file

43 Image Stacking

44 Image Stacking

45 Image Stacking Single frame from AVI Stacked image

46 Image Deconvolution

47 Image Deconvolution

48 Adding Colour Alexandra Hart

49 Adding Colour

50 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.

51 Future CMOS without Newton Rings More speed More sensitivity Tuneable wavelength narrow band camera!

52 Thank You