1. For current 40 and 10-cm telescope configuration (295 and 291 pair)
Assume: 3.5mJ/pulse, 30Hz (will not be used, since already use shots),
2005 mean O3, 30 zenith, rural aerosol, 60% optical eff. (excluding solar filter, this doesn’t affect
the solar/BG ratio because both laser and solar will multiply this eff.), 25% quantum eff.,
1.5mrad FOV, solar filter T as following.
For 10-cm telescope, FOV=3mrad
Signal-to-solar-background ratio gives you a sense how relative big they are. But it’s not SNR,
not even close (so it’s misleading). Below 10km, the signal/BG >5, You can expect the statistical
error effect is much greater than solar. So, no much uncertainty difference the daytime and
nighttime. The solar BG of 788 counts/us/10-min (18000 shots), 0.044 counts/us/shot, is
consistent with the measured 1.5MHz (1.5*18000/40=675 counts). Since the small telescope
area is 1/16 of the large, so you expect the solar of small telescope is 788/16, but small has a
higher optical eff. And a larger FOV.
, Megie et al. 1985
, Papayannis 1900
SNR=Sigal/sqrt(Signal +BG+dark) , BG is solar background
The relationship is not linear and complicated.
1. Even BG is 10 times larger than P, SNR can be still greater than 1 because of square root.
For example, 100/sqrt(100+1000)
2. Increasing delta r can reduce uncertainty
3. O3 error is approximately proportional to SNR. SNR=1 doesn’t mean 100% uncertainty.
40-cm telescope
10-cm telescope
Since works for zenith angle 30, so don’t need to check 45 and 60 zenith angle.
2. For 289 and 299 pair, change: Power=6mJ/pulse, and solar filter T as follows, no
interference filter (IF), OD6 longer than 303nm, 40 cm still uses 1.5mrad FOV, and 10-cm
uses 3mrad FOV.
Following is for 40-cm telescope.
Then change zenith angle from 34 to 45, get following
So, no much difference for OD6 and OD5. Then still 45 zenith, but change >300nm blocking
from OD6 to OD5 , get following
Then, OD 4 get following
Noticeable decrease of signal/BG.
Then zenith 45, OD6, and double 2005 mean O3,
Following is for 10-cm receiver. FOV=3mrad
Then double O3, get following
So wide band will work for 10-cm receiver.
Now, calculate 1-inch mini receiver. A=5.07E-4, FOV=10mrad, 30-m resolution, others
keep same, same solar filter, 10min, 289-299 pair
Then, do 283.6-289
Mini receiver measures up to ~1.5 with 30-m and 10-min resolution. Note here basically
shot noise limit (statistical dominates). It will work theoretically using wide band although I
suspect the optical geometric is harder.
Now investigate the IF effect. Change FOV from 1.5 to 1mrad. Does Newport 12% peak
T, 10-nm bandwidth (same for other vendors) filter work?
Looks can’t measure high due to the low peak T and wide bandwidth. (forgot to consider
50% T after using a beamsplitter)
Then do 299
This is ok.
Then do high performance narrower bandwidth IF. Bandwidth=1nm, 50% beamslippter
Here the IF T already includes beamsplitter.
Then, beamwidth=2nm
2-nm IF is very realistic, you may double ozone, but still expect 10km. If use IF for 285, 285 will
be shot noise limit, from previous result 285 will measure up to 10-12km.
So the solution is: IF and beamsplitter for 40-cm receiver and only solar blind filter for other two.
2.5cm
Large receiver
BP: Band-pass
Ch: Channel
Lens
40cm
Solar blind filter, Pass
<301nm, blocking OD6
Field
stop
50/50 or diachronic Beam Splitter
Small receiver
PMT
Ch6
10cm
283/289 PMT
Broadband 283-289nm
Interference filter 299±1nm
Not
employed
299
Ch4
Solar blind filter
5%
Ch3
95%
PMT
283/289
Ch2
90/10 Beam Splitter
Ch5
CH1
Mini receiver
299
PMT
283&289
299&299
283&289
283&289
283, 289, or 299 Laser
Transient
recoder
Gate
299
Gate
Pulse
generator
Photodiode
Combined into
1 licel channel
Buy 283-289 IF and 299 2-nm width IF for 40-cm. Buy one 1-inch and two 2-inch solar filter, at
least, for other two receivers. You may buy IF later. Only solar will work but has an alt limit in
daytime.
Of course, you can use only two IF with high solar blocking for 40-cm scope.
(old: BG=34000 counts/us/18000-shots=1.9 count/us/shot. John get 2.6 count/us, but he use 30%
T (my total T is ~20%), so comparable. )