Starlight Instruments - Single Red Beam 1.25" Laser Collimator - 650nm

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Howie Glatter Collimators are one of the most well known brands of collimation tools.

SKU: STI-SI-LC125-650
Manufactured by:
Starlight Instruments

Product Description

Howie Glatter Single Deep Red Beam Laser Collimator 1.25" 650nm

Howie Glatter Collimators are one of the most well known brands of collimation tools.

"The lasers in my collimators are class IIIa lasers (maximum beam power: 5 thousandths of a Watt), and are quite safe if used with reasonable precaution. Direct or mirror-reflected eye exposure to the laser beam should always be avoided! You must be careful when collimating to ensure that the beam does not enter anyone's eye. There is no problem in viewing the beam's impact directly on a surface as long as the surface produces a diffuse reflection. The beam impact may also be safely viewed on a mirror or lens surface if the reflected or transmitted beam is not directed towards your eye. Information from studies I have seen suggests that in order to induce permanent damage, a class IIIa laser beam must stay focused on the retina for a long time. It's unlikely for this to happen because the pupil is a very small target and because we have a blink and aversion reflex to bright light. However, all precautions should still be followed to avoid the beam entering anyone's eye! A badly miscollimated Newtonian or Cassegrain telescope may allow the beam to exit the front of the telescope, so when collimating, check first by pointing the telescope at a wall or screen to see if the beam is getting out. With unobstructed telescopes such as refractors, the beam will always exit the front of the telescope, so run a strip of masking tape across a diameter of the dew cap opening as a safety beam stop.

The collimator interior has a solid-state laser diode, emitting an intense laser beam through a front aperture along the cylindrical collimator's body's central axis. This serves as a "reference line" from which alignments are made. If the beam isn't perfectly aligned with the cylindrical axis, the telescope optics will be off-center and asymmetric and will resulted in aberrated images.

"When I started manufacturing laser collimators I realized that in order to produce consistent and accurate results they must be highly resistant to mechanical shock, so that internal laser alignment is maintained. I experimented with this aspect of collimator construction and developed a design which tremendously increased shock resistance. After aligning the laser within 15 arc seconds, I shock test each collimator by whacking it against a block of urethane plastic (urethane prevents marring), striking it at least a dozen times on three axis. I then recheck the laser alignment, and if it has not changed the collimator passes. I believe this is the most important difference setting my collimator apart from all others I know of. They will withstand a shock equivalent to dropping from eyepiece position, up the ladder on a big Dob, without alteration of laser alignment."

The beam from red diode lasers is fuzzy-edged and elliptical in cross-section, but Howie Glatter collimators have a removable accessory plastic aperture stop with a 1mm hole that allows for a more accurate alignment. With the holographic collimators, it is not used at the same time as the optional holographic feature, and the diffractor must be removed to install the stop. With the stop inserted the beam impact at a distance of one meter or more looks like a star diffraction pattern, with a central dot surrounded by diffraction rings. The surrounding rings can help in centering the beam very accurately.

Howie Glatter offers red holographic collimators with a choice of 650 nm or 635 nm wavelengths. While the radiometric power output of the two versions is quite the same, the 635nm laser appears brighter since human eye's are more sensitive to shorter wavelengths. he higher cost of 635nm laser diodes increases the collimator price, but it enables optional holographic collimation in brighter ambient light. If you intend to collimate in early twilight, it is a good choice. In darkness, however, the 650nm laser is quite adequate. Because single beam collimators concentrate all the laser light in the central beam, the 650nm laser is quite adequate for them."


Name Starlight Instruments - Single Red Beam 1.25" Laser Collimator - 650nm
Manufacturer Starlight Instruments
Model STI-SI-LC125-650


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