Mirror Blocks – Rear Loading


The RL25 mirror block is a rugged, backlash-free unit accepting mirrors of 50mm diameter and 10mm thick.
The main angle block and fittings are identical to the ‘TM25’ mirror unit (data section 62.0), but fitted with
a different type of mirror housing which allows access to the mirror by removal of a backplate.
Mirrors may be inspected, cleaned or replaced without affecting the mirror alignment setting.
Any mirror of appropriate size may be fitted. Standard units are supplied with NiCu mirrors, gold-coated.
Technical specifications
Dimensions : See Figure 62.71.
Construction : Aluminium alloy, black anodised.
Stainless steel mirror mount flange.
Clear aperture : 32.0 mm diameter.
Operation/alignment : Via 3 off tilt screws, using tommy-bar.
Range of tilt : ±1°.
Alignment accuracy : ±10 arcseconds or better.
Alignment stability : ±2 arcseconds or better.
Fittings : Standard 52.0 dia. x 1.5 pitch F/M thread, retractable coupling rings.
Or, connection to faces via M5 tapped holes (see fig. 62.71).
Cooling : Water, via 6/4 size pipe fittings.
Gas inlet : Side fitting 1/4″ BSP (see options).
Associated equipment
Model RL25 fits directly to OPG optical piping. (Data section 61.1)
Alignment crosswire MX25 fits directly into Model RL25 (with the entire rear mirror sub-assembly removed),
allowing alignment of the beam reaching the mirror unit. See data section 64.3.

The side gas inlet is used when the laser system designer wishes to provide a clean gas purge in the region of
the mirror. The side fitting is normally provided blanked-off, but at customer request may be fitted with any
appropriate pipe fitting (such as 6/4, 8/6, 10/8 sizes for example).
Mirror options, all 50.0mm dia x 10.0mm thick, include:
NiCu, gold coated (std), R>98.6% ULO Optics Part no 19.7NCA10-00
Cu ‘HS’ type, R>98.6% ULO Optics Part no 19.7HSA10-00
Cu ‘Goldmax’, R>99.7% ULO Optics Part no 19.7GMA10-00
Silicon, max R (CMR), R>99.7% ULO Optics Part no 19.7SIC10-00
Molybdenum, R>98.5% ULO Optics Part no 19.7MO10-00
Technical notes
With 3 off M5 screws removed, the user may lift-off the backplate, which is integral with a sprung watercooling
The mirror is retained by a special clamp ring and ‘O’ ring, which seal the mirror unit and allow the gas purge
facility to be used efficiently.
Unscrewing the clamp ring allows extraction of the mirror, which may be replaced against a precision internal
flange without alteration of the mirror alignment.
The sprung water-cooling plate and clamp ring arrangement are designed to eliminate any possibility of
mechanical distortion of the mirror.