Amendment 1.pdf

Amendment 1- Answers to Questions:

1.1 Operation over wavelength range of 1540 nm to 1570 nm Single line or achromat from 1540-

1570nm?

Achromatic from 1540 to 1570 nm.

1.2 Keplerian-type telescope Does it need to be Keplerian? Are you open to Galilean type?

ABSOLUTELY MUST BE KEPLERIAN! We need a “real” exit pupil at an accessible location.

1.5 Secondary beam 1/e^2 Gaussian waist diameter of 3 mm Are you looking for 80/3 expansion, say ~ 26.7x? 3mm collimated beam in and 80mm collimated beam out?

Yes. The expansion ratio does not need to be exact – we can accept a tolerance of +/- 5% on the expansion ratio.

1.6 Primary lens focal length (suggested) of 400 mm How flexible is the focal length; do you have any constrains over the length of the beam expander? What is the optimum length you are looking for?

The focal length of the primary lens can be longer – up to 600 mm. We would like to keep the overall length of the beam expander below about 65 cm (26 inches), though shorter is better.

1.7 Beam axis height (suggested) of 53.62 mm above mounting platform Is this the height from the optical axis of the beam expander primary aperture (100mm) to your optical bench?

Yes. However, this is not a hard specification. Ideally, the first 10 inches from the small end would allow for a height of 53.62 mm above our mounting platform.

1.8 Maximum power up to 1 W What is your collimated laser beam residual divergence?

The residual divergence (1/e^2 half angle) of the secondary (3mm diameter) beam is roughly 0.5 milliradians.

1.9 Wavefront flatness of 1/8 fringe We will design, build and test your beam expander at 1064nm and we promise diffraction limit ¼ PV or better performance at 1064nm, which would indicate a better performance at 1540-1570nm.

This would be acceptable if you can provide a hard “on paper” analysis showing the expected performance at 1550 nm is within our specifications. We are unfortunately all too aware of the troubles that come from using achromatic lenses outside of their design envelopes.