Hi Wendy,

When I first started looking at your file I saw that the output detector was receiving almost no power. I began to analyze that. I changed the source to a single axial ray and saved that trace as a Ray Database, expanded in branches. Looking at the database with the Ray Database Viewer, I could see the two branches that made it to the output detector -- one from the moving mirror and one from the fixed mirror. That looked correct.

So I changed the source back to 1e6 rays and 25 degrees. When I ran a trace I saw fringes on all detectors. I have no idea what changed. I attach a ZAR file of your design as I finished with it. You can see the database analysis. It is a really good way to look at issues like this.

Also, note that I attach a ZAR format, not ZMX. You can save a ZAR by choosing that format in the fie save process. It saves all aspects of the design and is a good way to share work.

Kind regards,

David

Hi David,

Many thanks for your help. 

I don't know why this happens,
In the design file, when the Minimum Relative Ray Intensity : 1.0000E-036 --> 1.0000E-006 is changed, the fringe is visible in the detector and the power is normally.