ViewSonic PJ870 Service Manual - Page 65

PJ870

the

warranty

period.

The

required

state

(light,

dark,

or

non

-saturated),

restrictions

on

location

within

the

array,

and

maximum

count

of

non-functional

mirrors

are

defined

only

for

particular

systems,

and

may

be

found

in

the

applicable

image

quality

specification.

The

non-functional

mirror

defect

growth

rate

shall

not

exceed

1

per

year.

The

degree

of

saturation

of

non

-saturated

non-functional

mirror

defects

depend

both

on

the

particular

defect

and

the

system

configuration.

Note

7

:

Blemishes

Non

-uniformities

in

the

mirror

array

or

optical

window

may

result

in

localized

variations

in

the

luminous

output

(i.e.,

blemishes)

across

the

surface

of

the

device

when

viewed

in

an

optical

imaging

environment.

Such

localized

non

-uniformities

may

result

from

a

varity

of

sources,

including

variations

in

tilt

angles,

mirror

cupping,

foreign

particles

on

the

array

or

inside

window

surface,

window

scratches,

etc.

The

magnitude

of

the

projected

non

-uniformities

is

highly

system

dependent.

Practicaly

speaking,

blemishes

arising

from

window

defects

will

be

of

a

common

size

which

depends

critically

on

the

system

optics.

The

effect

of

defect

size

is

generally

limited

to

the

differential

brightness

associated

with

the

defect

for

scratch,

dig

and

particle

defects

of

practical

size.

Restrictions

on

1

()cation

within

the

array,

maximum

count,

and

differential

brightness

are

defined

only

for

particular

systems,

and

may

be

found

in

the

applicable product

image

quality

specification.

Note

8

:

Placement

of

Active

Area

within

Package

The

positioning

of

the

die

active

area

within

the

hermetic

package

is

delineated

in

Figure

6,

Figure

7,

and

Figure

9.

Practical

optical

systems

will

need

to

comprehend

a

maximum

of

0.003"

variability

in

the

focal

plane

of

the

modulating

element

referenced

to

the

datum

[A],

Figure

7

in

the

absence

of

any

alignment

mechanism

in

the

system.

if

some

means

of

ratational

alignment

with

respect

to

the

system

optical

axis

is

comprehended

by

the

design,

this

variability

falls

to

0.0014"

per

Figure

7,

datum

[K].

The

in

-plane

rotational

angle

between

active

area

and

package

datum,

Figure

9,

note

3

is

0.0

+/-

0.8

degrees.

The

true

position

tolerance

relative

to

the

package

datum

is

0.5mm.

Note

9

:

Window

Optical

Properties

The

optical

quality

of

the

window

is

an

important

contributor

to

the

quality

of

the

projectedimage.

To

meet

the

uniformity

requirements

discussed

previously,

the

minimum

window

opening

defined

in

Figure

9

must

be

free

of

striae,

bubbles,

inclusions,

birefringence,

and

particles

which

might

degrade

the

optical

performance

of

the

packaged

DM1).

Visibility

of

scratch,

dig,

and

particle

defects

are

highly

system

dependent.

The

window

opening

must

not

block

any

dump

light

from

the

active

area.

To

maximize

contrast,

the

window

is

coated

on

both

sides

by

an

anti

-reflective

coating.

The

average

reflectance

shall

be

less

than

0.5%

for

wavelengths

of

420-700

nanometers

and

any

angle

between

normal

and

30

degrees.

The

index

of

refrection

is

specified

for

a

light

wavelength

of

545

nanometers.

IVIINVN

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