Howie Glatter Single Deep Red Beam 2" Barlowed Laser Collimator - 635nm
- Single deep red beam operates at 635nm for night time use.
- The Howie Glatter Laser Collimator incorporates a solid state laser diode that does not fade or change with time and use.
- Factory-aligned to 15 arc-seconds providing 0.1 inch accuracy at a distance of 20 feet.
- The Howie Glatter Laser Collimator is shock resistant to keep its alignment - even when dropped.
- Includes 123A lithium battery, 1mm aperture stop, case, collimation rings and instructions.
This Laser Collimator is very different from other Collimators!
Howie Glatter Single Deep Red Beam Laser Collimator 2" 635nm
Howie Glatter produces some of the finest laser collimators available today. Howie Glatter's Laser Collimators are precision machined to fit your focuser perfectly. Even the Laser itself is tuned to a higher brightness than others. The Glatter holographic collimator has in addition to the laser, a removable transparent diffractive optic (the "hologram") that is placed in the path of the beam, just ahead of the laser. It diffracts light from the laser to project a diverging, symmetrical pattern around the beam, which is quite useful for centering optical elements and other procedures. The grid covers a wider angular range (21 degrees) than any other holographic collimator which allows direct centering of f/ 2.7 to f/ 35 optics. A rectilinear grid pattern gives the highest accuracy and sensitivity for centering circular optics of arbitrary size.
When it comes to lasers and collimation, one of the most trusted names in the business is guru Howie Glatter. His uncompromising quality and dedication to above average products, not only put his name above the rest - but in demand as the finest available on today's market. Usually a manufacturer doesn't take the time to explain to a customer exactly why their product excels over others - or why it performs better - but not Howie. Here's what he has to say about his new Howie Glatter Laser Collimator:
"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.
Inside the collimator is a solid-state laser diode, which emits an intense laser beam through a front aperture, exactly along the central axis of the cylindrical collimator body. The beam acts as a "reference line" from which alignments are made. For a laser collimator it is of supreme importance that the beam be aligned with the collimator's cylindrical axis, for if it is not, the resultant "alignment" of the telescope optics will be off-center and asymmetric, and the telescope will produce 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 most important specifications for a laser collimator are the accuracy and stability of the laser beam alignment to the cylindrical axis of the collimator body. Glatter's alignment tolerance is fifteen arc seconds for single beam mode, and one arc minute for the holographic mode. In order to ensure maintenance of this level of accuracy each of these collimators are engineered and then tested for resistance to shock.
The beam from all red diode lasers used in collimators is fuzzy-edged and elliptical in cross-section. When collimating, you sometimes must judge the location of the center of the spot by eye. To improve collimating precision, all of the collimators (except 532nm) are supplied with a removable accessory plastic aperture stop having a 1mm hole, which push-fits into the laser aperture. It produces a tiny, circular beam impact which allows more accurate alignment.
A single beam laser can be used to align the secondary mirror to the focuser axis. When the primary is aligned, however, a Barlow must be used to align the return beam-the single beam is not accurate enough. Howie Glatter can provide a Barlow attachment with the laser (order a laser with the self-Barlow attachment), you can use your own Barlow, or you can buy a Howie Glatter BLUG to fit your focuser (simply the easiest way to use a laser for primary collimation).
Optional holographic attachments screw into the laser aperture and have a white screen front surface. They contain an optical element that diffracts most of the laser light into a diverging symmetrical pattern around the central beam. The projected pattern is useful for centering optical elements by making it symmetrical with the edge of the optic.
Primary mirror collimation is the most critical adjustment in a Newtonian, and it’s been realized that with modern fast focal ratios of f/4.5 and faster, the errors which can occur in laser collimating the primary using the conventional method of folding the beam back on itself can exceed good collimation tolerances. The Barlowed laser procedure, invented by Nils Olof Carlin, is a more accurate laser-based method of collimating Newtonian primary mirrors. It was originally done by inserting a laser collimator into a Barlow lens in the focuser, with a paper screen attached to the front of the Barlow. The combination projects a silhouette shadow of the primary center mark back to the screen on the Barlow device. The primary is adjusted by centering the shadow on the screen. Unlike conventional laser primary collimation, the adjustment is relatively insensitive to inaccuracy or "slop" in the fit of the collimator in the focuser, or small errors in secondary alignment.
Normally, parallel rays of light from a distant star travel down a telescope tube, and upon reflection by the paraboloidal primary mirror, are converted into a converging beam in the form of a cone. The cone forms a point image of the star at the mirror’s focal plane. Barlowed laser collimation takes advantage of the fact that a telescope will work in reverse. When parallel rays of light from the laser pass through the negative Barlow lens they are refracted into a diverging beam, also in the form of a cone. If the rays are traced back through the Barlow lens, they would appear to emanate from a virtual point source in the center of the focal plane, just like a star image. The diverging rays are reflected by the secondary mirror onto the primary mirror, where they form a blotchy patch, similar to a magnified image of the original irregular laser beam.
When the primary mirror reflects the beam back up the telescope tube the parabola works in reverse, converting the diverging rays into parallel rays. Where the primary is covered at its center by a collimation mark or ring, it is blocked from reflecting, so the upward travelling beam contains within it the superimposed dark shadow of the collimation target. The shadow remains sharp because the rays are parallel. The beam is reflected by the secondary back to the Barlow screen, where the shadow of the collimation mark surrounded by laser light is seen. The primary is adjusted using its collimation screws to center the target shadow around the hole in the screen.
Since the virtual point source is located at the focal point of the primary, the position of the shadow on the screen is a true indication of the primary mirror optical axis (if the collimation mark is accurately placed), and is effected very little by variations in the aim of the point source beam. It is startling at first, as the collimator and Barlow are wiggled around in the focuser, to see the shadow of the collimation mark remain almost stationary.
Howie Glatter's collimators offer red with a choice of either 650 nanometer or 635nm wavelength. The two lasers have the same radiometric power output, but because the human eye's sensitivity to the shorter wavelength is greater, the 635nm. laser appears about two or three times brighter. The higher cost of 635nm laser diodes increases the collimator price, but it enables 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||Howie Glatter - 2"Collimator 635nm Holographic and Barlowed|
|Alignment Procedures||15 arc-seconds providing 0.1 inch accuracy at a distance of 20 feet|
|Power Requirements||3V CR123A Lithium Battery|