My NS-system comprises 2 components only.

**1. Source Rectangle** x/y Half Width = 5mm; Cosine Exponent = 1; Power = 1W

This is nothing else than a pure Lambertian emitter.

**2. Detector Rectangle** x/y Half Width = 5mm; 100x100 pixel; 0.001 mm behind the source

This detector covers closely the Lambertian Emitter

The Power (P) of a Lambertian source calculates as:

P = pi * A * NA^2 * L

A: Area of source

NA: Numerical aperture of source; NA = 1 for hemisphere

L: Radiance

For L we get:

L = P / (pi * A * NA^2); P = 1W; NA = 1; A = 1cm^2

**L = 1 / pi = 0.318**

Ratracing confirms this calculation for radiance in angle space:

Of course there is a very little amount of noise...

When I switch the detector from Radiance in **angle space** to Radiance **position space**, the result gets **wrong **by a factor of 2:

Now I am really puzzled: A pure Lambertian source has a constant radiance in both, angle space and position space. Basically, the raytracing confirms this.

However, the radiance also needs the same numerical value in both projections. That is the nature of a constant.

The Zemax file is so simple that your engineers can set it up in seconds. The raytracing itself should not take long as well.

I am really curious about your comments.

Kind regards,

Joachim