Screens and projection · SERVICE · REV 2026-10-06
Laser projectors
Laser cancels neither throw ratio, nor screen gain, nor house light. It usually changes source life and the kind of maintenance as the device sheet says, not as this page promising hours. The seat near the booth hears the fan. That is a brief item.
Definition
Throw ratio is projector-to-screen distance divided by image width. The figure comes from the lens table at the shift required. Short and long are two geometry pages, and a laser may sit on either.
Light at the eye depends on lumens stated on a sheet measured by a named method (such as the ISO 21118 family for projectors where it applies), and on image size, screen gain, and ambient light. This page turns that neither into nits nor into a lumen band.
When is this service needed?
Lamp maintenance is the complaint
Laser is a discussion about replacing the source, not about image geometry alone.
A booth exists or is required
The device is heard and it heats. The seat stuck to the port pays.
A large picture without an LED wall
The optical path has to stay clear of heads and rigging.
Not a substitute for measuring contrast
A lit hall can stay washed out. Laser is not a curtain.
Where it is used
A lecture hall
Text on a screen. The lights dim or the contrast fails.
A theatre
A rear booth or a device in the house. The noise differs.
Home cinema and a box
Short throw may fit better. A separate page.
Not a sunny stadium
Projection there loses to the sun unless a sheet proves otherwise, and this page is not that sheet.
Parts of the solution
The device and its lens
The table ties distance to width and to shift.
The screen
Gain, direction, and acoustic transparency if the sound is behind it.
The path
Clear of heads, chandeliers, and rigging.
Thermal and acoustic isolation of the booth
If there is one. The door and the duct, not the glass alone.
Engineering considerations
No lumen band here
Figures such as 6 to 20 thousand circulate in the market. This page rejects them because they have no image size and no ambient.
ISO 21118 where it applies
A method for measuring device output, not seat brightness.
Noise
The device sheet in decibels under its conditions. Acceptance is a brief criterion, not a number we pick.
Keystone
Optical shift before digital correction. Correction eats pixels.
Safety
The laser class comes from the device sheet and the code. This page classifies no device.
Materials
The screen surface
Higher gain is not always clearer. The angle narrows.
Booth glass
It absorbs light and reflects. It is counted in the path.
The device mount
Roof vibration shows on a large picture.
Related systems
Control
On, off, and a source. Not DMX unless the device says so.
Audio
Picture delay against the array is reviewed in cinema and lectures.
Cooling air
It is not dumped on the nearest seat.
Emergency light
From the code. The projector is not escape lighting.
Design sequence
- 01
Fix the image width and the device position before the name of the source.
- 02
Read the lens table. Reject a throw with no shift.
- 03
Put noise and heat on the booth seat, not in the general specification.
- 04
Name the ambient: a lit lecture is not a dark film.
- 05
Do not write lumens from this page.
Delivery sequence
- 01
The path is built and confirmed clear before the device is hung.
- 02
The lens is the one in the table, not the nearest in the box.
- 03
Shift is set optically before any digital correction.
- 04
Noise is measured at the agreed seat if it is an acceptance item.
- 05
The source sheet is handed over as the manufacturer printed it, not as a marketing summary.
Testing
From the seat
Text at the true size under show lighting.
The path
No head shadow and no rigging shadow.
Noise
If it is written in the brief. The method is named.
Commissioning
The named source
Laser or lamp as installed. It is not swapped in silence.
Focus and edges
From the edges, not only from the middle of the screen.
What is not accepted
A factory picture on a slide, or lumens kept in memory.
Maintenance
Filters and the thermal path
From the device manual. This page gives no months.
Dust on the lens
It shows on the large picture before it is seen on the device.
Source replacement
The manufacturer’s procedure and the laser class. Not necessarily the old lamp routine.
Common mistakes
Laser means a daytime picture
Ambient still wins if the hall is bright and the screen gain is small.
Copying lumens from another job
Size and distance differ.
A device over the heads with no noise in the brief
The seat complains after opening.
Heavy digital keystone
Edges break and the text is lost.
Short comparison
The comparison is a way to choose a path. It is not a product recommendation and it is not a code.
| Path | Fits when | Weakens when |
|---|---|---|
| Laser | The source itself is rarely swapped, and the sheet describes the maintenance. | When the budget belongs to the booth and the screen first. The source does not repair a bad path. |
| A lamp | A lower first cost and a source change the manual already knows. | When hours are high and the swap breaks the season. |
| LED | House light that will not be beaten by darkness, and no optical path. | When pitch and distance do not meet in the budget. Read the indoor page. |
Discussion ranges
Any number here is a preliminary discussion range from practice or a named reference. Replace it with the project criterion, laboratory data, and on-site measurement.
| Item | What is discussed | Limit of this page |
|---|---|---|
| Throw ratio | Distance ÷ image width, from the lens table with the shift. | No ready ratio here. Short and long are a geometry decision. |
| Device lumens | From a sheet measured by a named method where ISO 21118 applies. | Not seat brightness. This page publishes no band. |
| Noise | From the device sheet under its distance and mode. | No acceptable decibel here. The brief writes it if it is required. |
| House light | A lit lecture is not a dark show. | No lux on this page. The code owns escape lighting only where it speaks. |
What this page does not claim
No fire classification, absorption coefficient, sound pressure level, or legal capacity on this page may be copied into a quotation. Those values come from a product test report, a measurement, or the local code adopted for the project.
Questions designers and owners ask
How many lumens do I need?
No answer from this page. Size, gain, ambient, and the device sheet. Copied market bands are rejected here.
Is a laser silent?
No. The fan remains. The nearby seat hears it if the booth is not isolated.
Does it replace LED?
When the path is clean and the light is controlled. Not when sun or a bright hall beats the screen.
Where is short throw?
On its own page. A laser may sit on a short or a long lens. Geometry is not the source.
Is this the commercial cinema page?
No. The auditorium and isolation between houses are on the cinema design page. Here the light source and its maintenance.
Technical sources
- The device lens table
Throw and shift. This page does not replace it.
- ISO 21118 where it applies
A measure of projector output, not hall brightness.
- The noise and heat manual
The decibel and cooling conditions. No acceptance figure here.
Last editorial review: 2026-10-06. Review means the text was checked, not that a project was measured.
Turn the question into a brief
A study starts from room volume, use, and existing condition, not from a product name. Fill the brief and copy it.
Project study form