MRLS 76 cm (30") Laser Ranging System

Lunar Laser Ranging Program

Optical

Primary Mirror

Diameter

72.6 cm (30") paraboloid

Focal length

228.6 m (90")

F-ratio

3.0

Cassegrain System

Secondary Mirror

20.0 cm (7.87") hyperboloid

Focal length

10.67 m (420")

F-ratio

14.0

Field angle

36 arcmin

Plate scale

19.33 arcsec/min

Coudé System

3 cm afocal lens collimates f/14 beam for 2.74 m travel path to beam-expanding and beam-splitting optics before entering laser and photo multiplier housings.

Coatings

Coudé path optics coated to maximize transmission of green (532 nm) light. Beam-splitter directs wavelengths < 555 nm to coudé and wavelengths > 555 nm to Cassegrain.

Mechanical

Primary Mirror

Weight

116 kg (256 lbs)

Thickness

12.7 cm (5")

Material

ULE fused silica

Telescope Tube

Diameter

85.95 cm (33.84")

Length

153.90 cm (60.59")

Telescope

Mount

alt-alt; horseshoe yoke

Drive

roller bearings; DC torque motors; 21-bit absolute encoders

Tracking

IBM PC compatible computer running LinuxOS; CAMAC interface

Guiding

Computer-controlled absolute pointing; Vidicon system at Cassegrain focus

Housing

40 foot semi-transportable carrier, expandable sides; swing-off roof

Historical

Construction

Started

1979

Funding

NASA Contract
NASW-3296

Contractor

Telescope

Victoria Machine Works

Milestones

Aug 1981

first LAGEOS acquisition

Aug 1983

first lunar acquisition

laser ranging system
laser ranging system