HoTech 1.25" SCA Laser Collimator - Single Dot

Our Price: $89.00
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In stock (10+ Available)
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Our Product ID: PALC-HT-SCA-1.25D
Manufacturer SKU: SCA-1.25D
Item Can Ship: Worldwide
HoTech 1.25" SCA Laser Collimator - Single Dot

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Product Details

Voted "Hot Product - 2009" by Sky & Telescope
"There is a tremendous amount of creativity and cleverness being displayed, all backed by a fervent devotion to making the sky more accessible and enjoyable for astronomy enthusiasts at all levels. It is truly inspiring." - Robert Naeye, Sky & Telescope Editor in Chief

  • Ideal for collimating Newtonian reflector telescopes. May also be used to collimate SCTs (additional steps required; see detailed product manuals/videos below before ordering).
  • Uses innovative Self-Centering Adapter technology for most precise centering and collimation
  • Made of aero-space grade lightweight aluminum material and CNC machined
  • 45-deg faceplate with targeting grid allows more convenient alignment from the rear of the telescope
  • Over 65 hours of operation with included CR123 batteries
  • Available in 1.25" and 2" models

Laser Collimator with Self-Centering Adapter (SCA) - Provides Repeatable Installation
The HoTech laser collimator separates itself from all other laser collimators with its innovative self-centering adapter technology (SCA). This mechanism allows precise and repeatable installation in all brands of 1.25" and 2" telescope focusers, thus providing accurate collimation. All laser collimators in the current market have one fundamental problem, slop in the adapting mechanism between the laser collimator and the telescope focuser. This problem is clearly recognized and often discussed among astronomers but so far there has been no definite solution in the market.

No matter how tightly the tolerances machined on the laser collimator or the focuser, a small gap is required to allow installation of the laser collimator. Once the laser collimator is inserted, the required gap becomes a problem. A laser collimator is secured with one or more thumbscrews or unified compression ring. Both methods introduce a very critical issue, namely an off-axis installment that instantly destroys the precision of your collimation instrument along the entire optical axis.

HoTech's Self-Centering Adapter cleverly eliminates the slop by linearly compressing the built-in rubber rings.
By doing this, the diameter of the rings expands to compensate the gap. Because all rings evenly expand radially in diameter from the compression, this automatically centers the laser collimator in the focuser draw tube. And most importantly, the SCA laser collimator can be tightly installed in the focuser for a repeatable installation to provide accurate collimation.

In summary, HoTech's SCA adapter serves three critical functions.
First, its expansion rings accommodate almost all focuser's manufacturing tolerances.  Second, it automatically centers the adapting laser.  Third, it provides at least two evenly distributed circular contacts on the focuser's inner tube surface preventing the adapting laser from pivoting.  Once the slop factor is taken away, you can quickly collimate your telescope in confidence to achieve perfect collimation every time.

Problem Solved with SCA Adapter Technology 

1. SCA Eliminates Drawtube Slop
All drawtubes have manufacturing tolerances. They require a larger diameter to accept various eyepieces and adapters. When a standard collimator is inserted, the gap between the drawtube and the inserting device becomes a slop problem. The rubber rings in the SCA expand radially according to users own adjustment to fill the gaps. This makes your collimator seat firmly in your drawtube, becoming part of your telescope for a secure and repeatable installation.

2. SCA Eliminates unstable locking from thumbscrew or unified compression ring
The optical axis is shifted when the inserting device is locked in by thumbscrew. In some cases, some poorly made unified compression ring can cause unstable tilt when locking in the drawtube due to loose tolerances between the compression ring, inner groove, and the uneven tip of the locking thumbscrew in a drawtube. The SCA adapts the collimator itself without using the thumbscrew or the unified compression ring.

3. SCA Accepts the Imperfection of a Drawtube
Despite small imperfections inside the drawtube like dents, scratches, and uneven burrs, the rubber rings compensate the errors and faithfully center the collimator in the tube. In addition, even if the drawtube is slightly deformed in diameter (egg-shaped), the rubber rings in the SCA will compensate for the differences and faithfully center the collimator. A metal collet design will not be able to transform itself to the deformed shape to compensate the imperfection of a drawtube for a sturdy adaption.

More SCA Laser Collimator Features:

Laser Engraved 45-deg Targeting Faceplate

The targeting faceplate displays the returning laser spot with a clear visual reference during adjustment. That allows you to align your primary mirror from the rear of the telescope eliminating traveling to the front of your scope repeatedly during collimation.

When collimating without the targeting faceplate, you will not be able to adjust the primary mirror in real time referencing the laser dot. In other words, you often get lost on which adjustment screws you used due to traveling back and forth for referencing the direction you have adjusted. This results in considerable time to complete the collimation and defeats the purpose of quick and easy laser collimation. HoTech understands the importance of this, so the faceplate is a standard feature in their laser collimators. All astronomers deserve to have it without paying anything extra!

In addition, the faceplate viewers pattern is laser engraved to ensure a long lasting sharp targeting grid for best visual effects. Unlike other collimators, the target is not a sticker that will peel, or paint that can rub off or chip. HoTech understands that you are paying for a precision instrument that is supposed to be well made.

Finest Projecting Laser Dot


Keeping the laser dot to the finest point is the key to precision collimation. But when you look closely at the laser dot from brand to brand, most laser dots appear large; not really a fine point as you might have imagined. This means that there is guess work involved when you try to center the dot; not just centering the laser dot to the center of the faceplate, but also centering the center of the dot itself. This does not make any sense when you are trying to take the advantage of the collimated laser beam's characteristic which has a low beam divergence, so that the beam radius does not undergo significant changes within moderate propagation distances. In other words, the laser beam size within the collimation distance (laser collimator to the primary mirror and back to the faceplate) should remain a constant fine point. As you know, most laser collimator brands are not really laser manufacturers. They install an off-the-shelf laser module or pointer and align the laser in a tube without REALLY considering the user’s application, namely the operating distance for a laser beam size. HoTech has been designing and building laser modules and systems for over 10 years for various professional industries. We know exactly how a laser should work. We limit our laser beam to the finest size in the correct operating distance for optimal effect. Our understanding and experiences with the laser design permit you to have an effective and precision collimation.

High Accuracy Laser Alignment
The HoTech laser collimator is well centered and aligned which are critical factors for an accurate collimation. But you will be surprised that many laser collimators in the market fail in this regard. The reason is in the design and understanding of the product itself.

HoTech has considered all aspect of parameters in their design. Parameters like the alignment mechanism, mechanical and optical structure of the laser itself, and more are taken as part of the laser collimator's design. For instance, some laser collimators actually install an off-the-shelf laser pointer in the casing. It is very cost effective (for the seller), but it inherits numerous problems. In many cases, the laser pointer might not install perfectly centered in the casing due to pointer size variations and the added alignment mechanism. So the laser itself is not positioned on the true alignment point and optical axis. As the result, the laser can never be center-aligned in the enclosure. It is possible to align the laser beam parallel to the optical path but always with an offset along the optical axis. This means the laser beam is off no matter how you center adapt the laser collimator to the focuser. The result of off-centered laser will introduce astigmatism into your telescope.

Light Weight Design and All Aluminum Body Machined with High Precision CNC
Many laser collimator manufacturers give users the wrong impression, big and heavy means rugged and stable. Instead, HoTech engineers successfully cut the unnecessary weight on the laser collimator because they understand that additional weight on a telescope (especially open structure Newtonians) will create imbalance and structure sagging. In addition, the heavier the device is, the more inertia it will have during an impact from an accidental drop. In such an accident, the inertia force can cause more damage to the internal alignment mechanism because there is more energy required to dissipate from the impact. Therefore, the lightweight design on this laser collimator makes you gain reliable precision collimation. And, of course, Hotech laser collimators use aerospace grade lightweight aluminum material and are CNC machined with the tightest tolerances, then sand blasted and anodized to protect them from harsh environments. Nothing has been sacrificed while you get a long lasting state-of-the-art collimation instrument.

Long Lasting Battery Life
By using a CR123, 3V battery as the laser power source, HoTehc's laser collimator has over 65 hours of continuous use battery life time. The included CR123, 3V lithium battery operates well under a typical cold night and it has a 10-year shelf life. This is a great advantage since you don't have to worry about changing the tiny, hard to find cell batteries frequently in the dark like other collimators.

Collimation for your SCT
Commercially made SCTs all have slight optical and mechanical alignment errors. The error typically is in the centering of the secondary mirror. As a result, when a laser is installed and emitted from the focuser, the beam will seldom return dead center, even though star testing would indicate perfect collimation! In addition, the secondary mirror (convex shape) magnifies any error by about 5 times. The error of deviation for a typical well-collimated SCT will return laser beam at around 0.125" to 0.25" off center. In order to compensate the optical and mechanical alignment errors of SCT, a different collimation approach is required in comparison with Newtonian telescopes. If the procedure is followed through correctly, users can still accurately collimate their SCT.

By default, the laser will have to be positioned in the optical center of the SCT. The HoTech SCA laser collimator automatically eliminates the focuser slop without using the thumbscrew and center-positions itself on the optical axis. For SCTs, the primary mirror is fixed, but you can collimate by adjusting the secondary mirror to a point parallel to the optical axis.

There is an one-time-only preparation that you need to do for SCT laser collimation using this collimator. First, install the SCA laser collimator and premark the laser position on the target grid of the collimator when your telescope is collimated from the factory or from your star collimation. Then when you check for collimation next time, just adapt the SCA laser collimator on the focuser, 2" or 1.25", and see if the laser falls on the premarked laser position. If not, adjust the alignment screws on the secondary mirror to move the returning laser dot to the premarked postion on the target grid. See illustrations below.


Diffraction Grating Pattern Lens on the SCA Laser Collimator
Since HoTech's SCA Laser Collimator is already accurate with the SCA technology, fine laser dot, and the built-in 45 degree faceplate, there is no need to use the DFG pattern to align the primary mirror of a Newtonian telescope. The purpose of using the DFG pattern is to eliminate gross misalignment the primary mirror. The user aligns the primary mirror by referencing the shadow of the secondary in the projected DFG pattern on a wall, and the user counts the DFG dots around the shadow to center in the shadow. This method cannot achieve accurate alignment because the gap between each dot can make a big alignment difference. At the final alignment stage, the user must bring the laser dot back to the laser exit (the center of the 45 degree faceplate). HoTech's built-in 45 degree faceplate allows you to align your primary mirror from the rear of the telescope eliminating traveling to the front of your scope repeatedly during collimation like other collimators. Therefore, there is no need to use DFG lens in conjunction with HoTech's SCA Laser Collimator.

Useful Resources

• User Manuals:

   • SCA Laser Collimator for Newtonian (PDF format)
   • SCA Laser Collimator for SCT (PDF format)
   • SCA Laser Collimator for Star Collimation (PDF format)
   • SCA Laser Collimator Specification (PDF format)
   • Laser Safety Precaution

• Videos:

Newtonian Style Telescope Laser Collimation


SCT Style Telescope Laser Collimation part 1


SCT Style Telescope Laser Collimation part 2


SCT Style Telescope Laser Collimation part 3


Crosshair Laser Collimator Video

Manufacturer HoTech
Model1.25" Single Dot SCA Laser Collimator
Focuser Size1.25"
Laser Wavelength650nm
Laser Output PowerClass II, < 5mW
Operating Voltage3V
BatteryOne 3V Lithium Battery (included), 10 yrs shelf life, 40+ Operating Hours
Weight3.4 oz. w/ battery
Dimension1.2"/30mm dia. x 5"/127mm (L)
ConstructionAll Areo-Space Grade Anodize Aluminum Case
Recommended Use Ideal for Newtonian Style Telescope, and SCT Style telescope requires one-time-only star collimation

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