q*c
发帖数: 9453 | 1 Theta=lamda/D
Theta is the angle of the object to Object Lense in Satelite.
lamda is the wavwlenght you use to observe.
D is the diameter of your cylindrically symmitrical lense.
So, as for visable light, the WL is around 550nm, 5.5*10^-7m,
theta=A/d
A is the size of OBJ and d is the distance.
A, say, is 0.25m, d is generally several hundreds of miles, say, 250km
for calculation convenience.
so theta= 0.25/250*10^3=2.5*10^-6
to see it clearly, we need
D=lamda/Theta=5.5*10^-7/2.5* | t*s
发帖数: 1 | 2 我对你所引用的550nm有疑问，如果用经典的
光学理论来考虑，只要底片离镜头足够远，
成像就会足够大，对吧？
另外，我觉得用最小角度来考虑是否也值得
推敲，只要想想我们天天看星星的情况就行
了，所以我还是想知道地面上一个高尔夫球
大小的一个点光源与背景需要多大的光强度
之比才能保证被卫星发现。
【在 q*c 的大作中提到】
: Theta=lamda/D
: Theta is the angle of the object to Object Lense in Satelite.
: lamda is the wavwlenght you use to observe.
: D is the diameter of your cylindrically symmitrical lense.
: So, as for visable light, the WL is around 550nm, 5.5*10^-7m,
: theta=A/d
: A is the size of OBJ and d is the distance.
: A, say, is 0.25m, d is generally several hundreds of miles, say, 250km
: for calculation convenience.
: so theta= 0.25/250*10^3=2.5*10^-6
| q**i
发帖数: 174 | 3 I believe for the issue at discussion, light
diffraction would be a/the limiting factor.
【在 t*s 的大作中提到】
: 我对你所引用的550nm有疑问，如果用经典的
: 光学理论来考虑，只要底片离镜头足够远，
: 成像就会足够大，对吧？
: 另外，我觉得用最小角度来考虑是否也值得
: 推敲，只要想想我们天天看星星的情况就行
: 了，所以我还是想知道地面上一个高尔夫球
: 大小的一个点光源与背景需要多大的光强度
: 之比才能保证被卫星发现。
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